Leave the installation of solar panels in Yokosuka City, Kanagawa Prefecture to Kakeru Koumuten Co., Ltd.!
For Solar Panel and Battery Installation in
Yokosuka City,
trust Kakeru Koumuten Co., Ltd.!
Kakeru Koumuten Co., Ltd. is a company specializing in exterior renovations based in Kanagawa Prefecture.
As a company strong in roofing work, we are entrusted withsolar panel installations and battery installations considering roofs and waterproofing!
“How to Choose a Solar Panel Contractor in Yokosuka City”
“Costs for Solar Panel and Battery Installation”
“Subsidies Available for Solar System Installation in Yokosuka City”
We will also explain the above three points!
Installing solar panels carries risks such as“the occurrence of leaks” and other troubles.
To ensure you have no regrets, we recommend obtainingcomparative estimates from about three companies!
Table of Contents (Tap to Open/Close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Yokosuka City
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Yokosuka City
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installation Contractor in Yokosuka City
- Benefits of Introducing Solar Equipment
- Points to Consider When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions About Solar and Storage Battery Installation in Yokosuka City
- If You’re Looking for a Solar Panel Installation Contractor in Yokosuka City, Contact Kakeru Koumuten
- Characteristics of Yokosuka City and Points for Solar Construction
- Service Area in Yokosuka City
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Yokosuka City
Regarding why we are entrusted with solar panel installation by customers in Yokosuka City,
“Our Unique Strengths in Solar Panel Installation That Cannot Be Replicated by Other Companies”
have received high praise from many customers.
so we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Also Handle Exterior Renovations Beyond Solar Panel Installation!
Issues such as leaks that occur with solar panel installations may be caused by insufficient checks on the roof and waterproofing at the installation site.
Even if one is knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside their expertise, so caution is necessary.
It is reassuring to have expertise in roofing to avoid maintenance and issues after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent issues after solar panel installation!
2.Equipment Specialized for Exterior Renovation
Kakeru Koumuten Co., Ltd. has prepared the following warehouses and material storage areas to provide low-cost, high-quality solar and exterior renovation work.
We have established five bases centered around Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Ownership of Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding based on construction conditions and can assemble scaffolding in-house.
By not outsourcing scaffolding work and using our own scaffolding team, we can also cut costs for scaffolding work.
We own scaffolding materials for approximately 50 single-family homes!
Even if there are height differences on the site, our in-house scaffolding team will plan the scaffolding according to the local conditions.
Storage of Materials in Our Large Warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, you canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, enabling us torespond quickly in emergencies!
Sorting and Transporting Waste Materials In-House
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior Renovation Dedicated Showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on roofing materials!
We can also provide simulations of potential earnings and installation costs when introducing solar panels!
Since roofing and exterior wall work often accompany each other, we also have samples of roofing materials and models that explain the structure, allowing for detailed explanations!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having a consistent system from inquiry to project completion, Kakeru Koumuten can provide high-quality roof renovations at reduced costs.
Additionally, one representative will handle everything from the estimate to project completion.
Since the担当者 does not change, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation, exterior wall painting, to roof renovations!
4. Various Permits and Skilled Workers
We have obtained construction industry licenses and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal and painting technicians, and we are confident in our construction skills.
We can also handle large-scale roof projects for factories and other facilities!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation work, we also provide our own施工保証 (leak warranty)!
(The施工保証 for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty without performing roof renovations. The施工保証 is separate from the manufacturer’s product warranty, and the scope and conditions vary based on the warranty details.)
Aftercare is available every year, and we send out annual notification DM.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roofing troubles and situations.
If you cannot access the roof at high altitudes, we can utilize a drone to assist!
During leak investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of the solar panels decreases due to dirt, we can provide cleaning services using specialized brushes.
We will respond according to your preferences.
7. Human Resource Development
We create various roof models for skill enhancement and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly provide technical training to ensure that all staff can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
Kakeru Koumuten provides not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar installation guidebook” and “profit and loss simulations” that take into account loan interest rates and electricity costs.
The profit and loss simulation can be created for projected cumulative profits and losses over 20 to 30 years.
Even customers who are not familiar with solar installations will receive materials that clearly summarize important points and disadvantages!
We encourage you to obtain comparative estimates and review plans from other companies!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 or 30 years.
Confirming whether it is safe to install them directly on the current roof is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, specializing in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Year Built | The fixing method varies depending on the roofing material, such as slate, tiles, metal roofs, and flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest a roof renovation first. |
| 2. Condition of Substrate and Waterproof Sheet | If the sheathing boards or roofing (waterproof sheet) under the roofing material are damaged, it will affect the fastening strength and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, can affect power generation. We will create a layout diagram from the drawings and on-site, and you can check it with a power generation simulation. |
| 4. Shape of the Roof and Usable Area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. Since the number of panels that can be installed varies depending on the size of the panels, we will compare based on the overall output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will confirm whether the method involves drilling holes in the roofing material for fastening or using brackets to secure the roofing material. The fixing method varies by technique, so please check the waterproofing treatment method for the fixing parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels being added. After investigating the existing roof, substrate, and load-bearing capacity, switching to lighter roofing materials may be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will check the installation location of the power conditioner and storage battery, as well as the wiring route to the distribution board. The length of the wiring also affects the cost. |
| 8. Ease of Scaffolding Setup and Delivery Route | If there is a height difference on the site, planning for scaffolding and the delivery route for equipment and materials may require some ingenuity. The width of the front road and any steps on the site will also be checked during the on-site survey. |
Fixing Methods and Checkpoints by Roofing Material
| Roof Material | Main Fixing Method | Pre-installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (e.g., fixing brackets to the roof material and substrate with screws) | Waterproof treatment of fixing parts, cracks or deterioration of slate, condition of the substrate. If deterioration is advanced, consider roof overlay or replacement first. |
| Tile Roof | Fixed with brackets and methods suitable for the type of tile (even methods that do not drill holes in the tiles will secure to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the investigation results, there may be a method to replace with lightweight roofing material before installation. |
| Metal Roof (Horizontal/Vertical) | Fixed with catch-type brackets that grip the roof material (depends on the combination of roof material and brackets) | Whether the roof material and brackets are compatible, installation conditions from the roof material manufacturer. If compatible, a method that does not drill holes may be available. |
| Flat Roof/ Rooftop | Fixed by installing a framework | Type and deterioration status of the waterproof layer, waterproofing around the framework. Consider in conjunction with the timing of waterproofing work. |
If you perform roof renovations 10 to 20 years after installation, there will be additional costs for solar panel removal. If the roof is deteriorating, it may be more cost-effective in the long run to renovate to a highly durable roofing material before installation.
Kakeru Koumuten is strong in roofing work and can also handle solar panel removal in-house, so please consult us according to the condition of your roof!
▶ For information on roof renovations in Yokosuka City, click here
PotentialSubsidies and Grants in Yokosuka City, Kanagawa Prefecture
If you introduce solar panels or storage batteries in Yokosuka City, you may be eligible for programs from the “National Government,” “Kanagawa Prefecture,” and “Yokosuka City.”
The following information is based on the official pages of each program as of October 6, 2026. The application status may change based on the budget, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Yokosuka City “Key Measures Acceleration Project Subsidy (Residential Self-Consumption Solar Power Generation Equipment & Combined Storage Battery (Self-Owned))” | For those installing in residential properties within Yokosuka City. Must self-consume 30% or more of generated power and not obtain FIT/FIP certification. Solar carports are not eligible. Storage batteries must be introduced simultaneously with solar power (storage batteries alone are not eligible). No delinquency on municipal taxes. In principle, work should commence after grant decision (prior notification is required in unavoidable circumstances). Performance reports are due by February 15, 2027. | Solar Power: 70,000 JPY per kW (rounded down for less than 1 kW, calculated based on the smaller output of the panel and power conditioner) Storage Battery: One-third of the total of the storage system and construction costs (storage system capped at 141,000 JPY/kWh) |
May 1, 2026 – January 15, 2027 According to the city’s official page (updated October 1, 2026, as of September 30), applications for residential solar power are possible (execution rate 80.4%), while applications for residential storage batteries have closed as the budget has been reached. |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Residential Solar Power Generation & Storage Battery Installation Subsidy” | Must install both solar power generation and storage systems in residential properties (with ensured seismic performance) within the prefecture. Applications must be made by the individual, and work should commence after grant decision. | Solar Power: 70,000 JPY per kW Storage Battery: 150,000 JPY per unit |
Phase 1: May 11, 2026 – June 30, 2026 Phase 2: Starts September 7, 2026 (first-come, first-served) As of September 7, 2026, applications have reached the budget limit and are now closed. Please check the prefecture’s official page for future recruitment. |
| National “DR Home Storage Battery Project” (Fiscal Year 2025 Supplement) | Newly introduce registered home storage systems that can be utilized for DR (demand response). | Calculated based on an initial effective capacity of 34,500 JPY per kWh (subsidy rate within 30% & maximum 600,000 JPY per application). | As of May 29, 2026, the budget has been reached, and public recruitment has ended (the official site states there are no plans to reopen public recruitment, and applications are currently not possible). |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Storage batteries are one of the eligible facilities, but they must be combined with essential works such as insulation renovations of windows (openings) and structures; applications cannot be made for storage battery installation alone. Solar panels are not included as eligible facilities. | Storage Battery: 96,000 JPY per unit | Ends as soon as the budget limit is reached. The official site indicates that as of October 5, 2026, renovation applications account for 8% of the budget. Please check the official site for application status. |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Self-Consumption Renewable Energy Installation Subsidy” | Corporations and individuals filing blue returns (individual residences are not eligible). Solar power must have a generation output of 10 kW or more, for business facilities, and equipment that does not receive FIT/FIP certification. | Solar Power: 80,000 JPY/kW, etc. Storage System: 50,000 JPY/kWh (maximum 5,000,000 JPY) |
Application closed on September 3, 2026 (application amount reached the budget limit) |
Yokosuka City’s key measures acceleration project subsidy for home storage batteries has ended, and the budget execution rate for home solar power is also increasing. As a general rule, the city’s subsidy requires work to commence after the grant decision, and Kanagawa Prefecture’s residential subsidy also requires construction to start after receiving the “grant decision.” If work begins beforehand, it will be excluded from eligibility. Each program has different eligibility conditions, application procedures, and whether they can be combined, and applying does not guarantee a grant, so please confirm before contracting or starting work.
At Kakeru Koumuten, we will provide guidance on eligibility conditions and application periods for each program after confirming them.
National Subsidy “DR Home Storage Battery Project (Support for the Introduction of Home Storage Systems for DR Resource Implementation)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program targets those who are newly introducing registered storage systems that can be utilized for demand response (DR), and in the fiscal year 2025 supplementary budget, the subsidy amount is determined based on a standard amount of 34,500 JPY per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum of 600,000 JPY per application. There are conditions such as that contracts or orders made before the grant decision are not eligible.
However, the fiscal year 2025 supplementary budget application amount reached the budget on May 29, 2026, and the public recruitment has ended. The official site also states that there are no plans to reopen the public recruitment, and applications are currently not possible. Please check the official site for future public recruitment.
Additionally, there are currently no subsidies from the national government specifically for the installation of solar panels on existing homes.
👉 Here is the official site for the DR Home Storage Battery Project
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Residential Solar Power and Storage Battery Installation Subsidy”
Kanagawa Prefecture provides subsidies for those who install both “solar panels” and “storage batteries” in their homes.
The subsidy details are 70,000 JPY per kW of solar power generation output and 150,000 JPY per storage system.
For example, if you install a 4 kW solar panel and one storage battery, the subsidy amount calculation would be 4 kW × 70,000 JPY + 150,000 JPY = 430,000 JPY.
The eligibility includes homes that ensure seismic performance, the storage system must be a registered product, if construction starts before the grant decision, it will be excluded from eligibility, and the application must be made by the individual (applications by contractors are not permitted), among other conditions. The possibility of combining this with Yokosuka City’s subsidy varies by program, so please check the official pages of each program before contracting.
For the fiscal year Reiwa 8, applications for the first phase (May 11 – June 30) and the second phase (starting September 7, first-come-first-served) were accepted. The second phase has been closed as of September 7, 2026, when the application amount reached the budget amount. Please check the official Kanagawa Prefecture page for future recruitment information.
👉 Click here for the official Kanagawa Prefecture page
Kanagawa Prefecture “Reiwa 8 Fiscal Year Kanagawa Prefecture Subsidy for Self-Consumption Type Renewable Energy Introduction Costs” (for businesses)
Kanagawa Prefecture is also implementing a subsidy for businesses that introduce “self-consumption type” facilities that use electricity generated by solar panels.
Eligible applicants are corporations or individual business owners filing blue returns, and the introduction to individual residences is not eligible.
Solar power generation must have a generation output of 10kW or more, supply electricity to business facilities within the prefecture, and not be equipment certified under FIT or FIP, among other conditions.
The subsidy amount is 80,000 yen per kW for solar power generation and 50,000 yen per kWh for the accompanying storage system (with a maximum of 5 million yen).
As the application amount reached the budget amount for the fiscal year Reiwa 8, recruitment was closed on September 3, 2026.
Businesses considering the installation of solar panels on commercial buildings in Yokosuka City should check the official Kanagawa Prefecture page for the next recruitment.
👉 Click here for details
Yokosuka City “Reiwa 8 Fiscal Year Key Measures Acceleration Project Subsidy (Household Self-Consumption Type Solar Power Generation Equipment and Combined Storage Battery (Self-Owned))”
Yokosuka City is implementing the “Key Measures Acceleration Project Subsidy” for those who introduce self-owned solar power generation equipment and storage batteries to residences within the city.
●Solar Power Generation Equipment: 70,000 yen per kW (rounded down for less than 1 kW; calculated based on the smaller of panel output and power conditioner output)
●Storage Battery: One-third of the total of the storage system and construction costs (the upper limit for the storage system is 141,000 yen/kWh)
The storage battery must be introduced simultaneously with the solar power generation equipment, and installation of the storage battery alone is not eligible.
Eligible applicants are those installing in residences within Yokosuka City, with conditions including consuming more than 30% of the generated electricity for self-consumption, not obtaining FIT or FIP certification, not being a solar carport, and having no delinquency in municipal taxes. In principle, work must begin after the grant decision, and prior notification is required in unavoidable circumstances. The application period is from May 1, 2026, to January 15, 2027, and performance reports must be submitted by February 15, 2027.
According to the city’s official page (updated October 1, 2026), as of September 30, 2026, applications for residential solar power are possible (execution rate 80.4%), while applications for residential storage batteries have ended as the budget has been reached. The application status may change, so please check the city’s official page for confirmation.
👉 Here is the official page of Yokosuka City
Solar Panel Installation & Storage Battery Installation Price List
⇧Service Menu | For costs related to solar panel removal and water heater removal, click here
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and storage batteries should be confirmed by separating “equipment costs (device costs)” and “construction costs”.
Even for the same “complete solar panel installation,” the amount can vary significantly depending on the installation capacity, the grade of the equipment, and the condition of the roof.
Considerations for Installation Capacity (kW) and Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of one panel (W) × Number of panels”, with the unit being kW (kilowatts). The battery is compared in terms of the amount of electricity it can store, represented in kWh (kilowatt-hours).
The amount of kW that can be placed on the roof varies for each house depending on the shape, orientation, and size of the roof. At Kakeru Koumuten Co., Ltd., we create layout diagrams from blueprints and on-site surveys to present the installation capacity.
On our pricing page, we list the cost of solar panels as approximately 800,000 yen to 1,200,000 yen for 3 to 5 kW, and 1,200,000 yen to 1,900,000 yen for 6 to 10 kW. (These are just rough estimates and may vary based on factors such as wiring length, scaffolding area, existing roofing materials, and panel layout.)
▶ Installation Menu | Costs for Solar Panel Installation and Battery Installation
Items to Check in the Estimate (Cost Verification)
When comparing estimates, it is common to compare different capacities and equipment based solely on price. Please check if the following items are clearly stated in each company’s estimate!
| 1. Solar Panels | Manufacturer, model number, output of one panel (W), number of panels, total installation capacity (kW) are listed. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls the battery together. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range usable during power outages (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of hardware suitable for roofing materials and method of securing (whether it involves drilling holes or clamping). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, presence of a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at fixed points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | Extent of support for applications to the power company, certification applications for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If it is simultaneous with roof work or exterior painting, check that the same scope and quantity are not double-counted. |
| 9. Removal and Disposal | Whether the removal of existing solar thermal water heaters or old panels and disposal costs for waste materials are included. |
| 10. Tax Classification and Warranty | Whether prices are tax-inclusive or exclusive, conditions under which additional costs may arise, and details and duration of manufacturer and workmanship warranties. |
If the capacities differ, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome comparisons of estimates, so if you bring estimates from other companies, we will explain the differences item by item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can get an estimated quote and income simulation for up to 30 years!
If you know the total installation capacity of solar panels on the roof and the capacity of the storage battery, you can obtain an estimated quote and income simulation!
*The simulation results are estimates. Actual income may vary based on assumptions such as electricity rates, self-consumption ratios, selling prices, and costs for equipment inspection and replacement.
Customer Feedback
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customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
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customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
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customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
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customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
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customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
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customer reviews
Higashiyamato City, Tokyo | We received reviews about exterior painting and roof overlay (cover method)!
Case Studies of Solar Panel Installations
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh |
| Base Mounting Hardware Used |
| Niigata Manufacturing/Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Arrangement |
| Fixed using catch type hardware gripping the horizontal metal roof (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the subsidy being granted, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The subsidy amount and recovery estimate are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| Approximately 3 days |
| Completion Month |
| April 2025 |
| Inquiry Details |
| I am considering the installation of solar panels and storage batteries. I heard that subsidies are available, and I would like to know how much will be granted. |
Our Proposal
We visited to provide an estimate and created a layout diagram for the solar panels from the drawings!
The layout diagram shows the arrangement of solar panels when placed on the roof.
Since we can also determine the installation capacity, it allows for power generation simulations and financial simulations.
We understood the expected amount of the subsidy, so we explained it to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Yokosuka City
There are many solar panel installation contractors available in Yokosuka City, and it can be confusing to decide which one to choose.
For this reason,when requesting the installation of solar panels or storage batteries, let’s confirm the following 4 points.
● Not only knowledge of solar power but also extensive knowledge about roofs
● Confirm the existence of warranties and after-sales maintenance
● Obtain estimates from multiple contractors (3 companies as a guideline)
● Check if they provide support for subsidy applications
By confirming the above 4 points, you will be able to choose a reliable contractor.
Knowledge of roofs as well as solar panels
Defective installation of solar panels may be caused by a lack of knowledge and confirmation regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient checks on roofs and waterproofing
・Solar panels installed on a deteriorated roof causing leaks
・Solar panels installed on a roof with a short lifespan, requiring remodeling to detach the solar panels within a few years
・Incorrect treatment due to misjudgment of the type of waterproofing, leading to leaks
and more
When installing solar panels, understanding the condition and type of the existing roof allows you to avoid unnecessary expenses and unexpected troubles.
▶ Go to “Roof Check Before Installing Solar Panels” in this article
Confirm the existence of warranties and after-sales maintenance
When choosing a solar installation contractor, let’s confirm the existence of warranties. It is important to check not only the duration of the warranty but also the coverage, exclusions, and cost conditions.
While the solar panels and storage batteries come with a manufacturer’s warranty, also check for the existence of a workmanship warranty in case leaks occur after installation!
For contractors that offer a workmanship warranty, if leaks occur after installation, they may cover the repairs under the warranty, provided it is within the warranty period and conditions.
Additionally, some contractors offer after-sales services separately from warranties, so make sure to check if the contractor you are considering has after-sales service.
Since abnormalities or damages on the roof may not be visible, you might not notice them yourself.
By conducting inspections of hidden areas through after-sales maintenance, you can more easily detect abnormalities early and prevent major repairs or breakdowns!
Kakeru Koumuten Co., Ltd. offers a rain leak warranty as part of the workmanship warranty for solar panel installations. (The warranty for solar panel installations is 10 years, and depending on the condition of the roof before installation, we may not be able to provide a warranty without performing roof renovations.)
We also provide aftercare maintenance and send out annual DM!
After checking the DM, if you wish, we will visit for aftercare maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, let’s obtain estimates from multiple contractors.
Even for the same manufacturer and the same work content, costs may vary, and warranties and after-sales services may differ.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request from your preferred contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates,
“Check the estimate items”
“Type of solar panel”
“Warranties and after-sales services”
let’s carefully compare and make a judgment! If the rank of auxiliary materials is low or if steps are skipped, costs can be reduced, so avoid judging solely based on price!
▶ Go to “Breakdown of installation capacity, equipment, and construction costs” in this article
Check if they provide support for subsidy applications
There may be subsidies available for solar panel installations and battery installations, but if the order of procedures is incorrect or if there are deficiencies in the documents, the subsidy may not be granted.
For systems like Kanagawa Prefecture’s housing subsidies, where the contractor cannot apply on your behalf and personal application is required, it is reassuring to have a contractor that supports the preparation of necessary documents and the flow of procedures.
Complete the procedures specified for each system (for the prefectural housing subsidy, this means obtaining a grant decision) before proceeding with the construction!
For the prefectural housing subsidy, after the construction is completed, a performance report will be submitted, and the grant will be provided after review! (The flow of procedures varies by system)
▶ Go to “Subsidies and grants that may apply in Yokosuka City” in this article
Benefits of Introducing Solar Equipment
The benefits of introducing solar panels are as follows!
Benefit 1 Economic Benefits
The biggest advantage of introducing solar panels is the economic benefit!
The selling price of electricity has decreased compared to 10 years ago, but by consuming the electricity generated, you can reduce the amount of electricity purchased from the power company and gain benefits!
As electricity costs rise, the ability to cover consumption with solar power becomes attractive!
If you want to use the generated electricity at night, installing a storage battery is essential!
Furthermore, the selling price (FIT) for residential use (under 10kW) will be set as “24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year” for certifications after October 2025, and the same price will apply for the 2026 fiscal year. After the 5th year, it is generally more advantageous to use it at home (self-consumption) rather than selling it, so combining it with a storage battery is also an option.
👉 Ministry of the Environment and Energy | For purchase prices and periods, click here
Advantage 2 Subsidies can be utilized!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the conditions, you may be able to utilize subsidies!
Reducing the actual burden through subsidies is a significant advantage!
In the case of Yokosuka City, there is a possibility of being eligible for programs from the national government, Kanagawa Prefecture, and Yokosuka City (please check the application status for each program).
Advantage 3 Environmentally friendly!
Solar power generation has low carbon dioxide emissions and can reduce dependence on fossil fuels, contributing to the mitigation of global warming.
Solar panels themselves do not produce noise or exhaust gases during the generation process, making them an environmentally friendly method of power generation. (However, devices such as power conditioners may have operational noise.)
Advantage 4 Heat insulation effects can be expected!!
By installing the panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, this can help reduce the temperature of the roof, providing expected heat insulation effects!
（This does not improve the insulation performance of the building itself）
Benefit 5 Electricity can still be used during power outages!!
If a storage battery is installed, it is possible to use electricity even during emergencies such as power outages!
Even without a storage battery, if you have a power conditioner with autonomous operation capability, you may be able to use electricity from a dedicated outlet during daytime generation.
（The devices, output, and duration that can be used during a power outage vary depending on the model and wiring method）
What points should be noted when introducing solar power generation?
Next, we will explain the “three points to note” when installing solar panels!
Point 1 Maintenance costs can be incurred
A particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reattaching the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing the solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to consider maintenance costs in the simulation before introducing solar panels!
Point 2 The risk of leaks may increase depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but when using screws or other fasteners to secure the roofing material and substrate, waterproofing of the fixed parts becomes crucial.
If the method involves making holes in the roof, the risk of leaks inevitably arises.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, replacing the roofing material with a metal roof and securing the solar panels using the catch method is also an option. (The catch method has compatibility conditions between the roofing material and the fasteners, and it cannot be used with all metal roofs)
Catch-type base hardware for horizontal metal roofs
Note 3: The roof will become heavier
Since solar panels will be installed, the roof will become heavier. After investigating the existing roof, substrate, and load capacity, replacing with a lightweight roof may also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
Choosing Method 1: Compare based on total output of the roof
When installing solar panels on the roof, it is important to know how much power can be generated in a limited area, and generating more power is always better!
Solar panels vary in size and output depending on the manufacturer.
A panel with an output of 350W and a panel with an output of 400W may seem that the higher output panel is better at first glance.
However, if the size of the panel does not fit well with the roof, “20 panels of 350W can be installed, while only 15 panels of 400W can be installed,” meaning the number of panels that can be installed on the same roof may differ due to the size of the panels.
400W×15 panels = 6kW (total output of the roof)
350W×20 panels = 7kW (total output of the roof)
As shown above, even if the output of a single panel is lower, the total output of the roof may be higher!
It is important to consider the total output of the roof rather than the output of a single panel!
*The above is a calculation of total output (kW). The actual power generation amount (kWh) will vary depending on conditions such as roof orientation, slope, and shading.
Choosing Method 2: Compare based on degradation rate of solar panels
Solar panels have a degradation rate, and their output gradually decreases after 10 years and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output guarantee values are standard figures for warranty purposes and do not indicate the actual degradation rate or power generation amount.
Choosing solar panels while considering the degradation rate, rather than just the initial output, will lead to a more satisfactory choice!
Choosing Method 3: Compare based on warranty period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Regarding output warranties, some manufacturers offer a 30-year warranty, while others provide a 10-year warranty, so it varies!
It’s always better to have a longer warranty, so let’s check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Yokosuka City
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Yokosuka City. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Yokosuka City?
The cost varies depending on the installation capacity, equipment, and condition of the roof. In the above construction example (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
For cost estimates by capacity, please refer to the solar panel installation and storage battery installation pricing page. We will create a layout diagram from the drawings and site survey and provide a free estimate!
Are there any subsidies available for solar power and storage battery installation in Yokosuka City?
As of October 6, 2026 (the city’s official page was published as of September 30), you can apply for the Yokosuka City Priority Measures Acceleration Project Subsidy (for households), where solar power (70,000 yen per kW) is eligible, with an execution rate of 80.4%. The subsidy for storage batteries (one-third of the total cost of the storage system and installation) has reached the budget limit and is no longer accepting applications. The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power and 150,000 yen per unit for storage batteries) was closed after reaching the budget amount on September 7 for the second phase of the Reiwa 8 fiscal year, and the national DR household storage battery project has ended its public recruitment.
Since the application status may change, please check the subsidy and grant section and consult with us before signing a contract.
Can I apply for subsidies even after the construction is completed?
Both the Yokosuka City subsidy and the Kanagawa Prefecture subsidy require procedures to be completed before construction. The city’s subsidy generally requires that work begins after the grant decision (a prior request is necessary in unavoidable circumstances), and the prefectural subsidy also requires “work to begin after the grant decision,” meaning that if you start work beforehand, you will be ineligible.
The order of procedures varies by system, so please confirm before signing a contract or starting construction.
Can solar panels be installed on a slate roof? I’m worried about leaks.
It is possible to install on a slate roof, but it is necessary to check the condition of the roofing material and substrate. The method of securing the panels varies by construction method, and when securing brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation, and if deterioration is advanced, we can also propose methods such as roof overlay (cover method) or re-roofing before installation.
My roof is old. Should I do roof renovation first?
It depends on the condition of the roof. If a roof renovation is needed after 10 to 20 years of installation, the cost for removing and reinstalling solar panels will be incurred separately. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with durable roofing materials before installation.
Please consult us about the installation process after confirming the condition of the roof through a site survey!
Is it better to install a storage battery together with solar panels?
For those who want to use generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price for electricity will be 8.3 yen/kWh after the fifth year, making it more beneficial to use it in your home rather than selling it.
Additionally, Kanagawa Prefecture’s subsidy requires the simultaneous introduction of solar panels and storage batteries, and the subsidy for the Yokosuka City priority measures acceleration project also applies only when the storage battery is installed at the same time as the solar power generation equipment; installation of the storage battery alone is not eligible. You can compare “solar only” and “solar + storage battery” in a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing roofs or roofs with shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten, we create a layout diagram from the drawings and site survey, and provide you with the installation capacity and power generation simulation.
In Yokosuka City, there are areas close to hills and mountains, as well as near the sea, so the shading from surrounding buildings and trees, as well as the installable capacity, will differ for each house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
In the above construction case (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roof work is done simultaneously or depending on the shape of the roof and installation capacity.
Please note that additional time is required for applications for subsidies and to the power company, so please consult us as soon as possible.
What is the current selling price (FIT)?
For residential use (under 10 kW), from the certification after October 2025, the first 4 years will be 24 yen/kWh, and from the 5th to the 10th year it will be 8.3 yen/kWh, and the same price will apply for the 2026 fiscal year.
The idea is to recover initial costs more quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-service maintenance notices via DM and visits customers who wish for inspections. We can also clean solar panels with a special brush if the power generation is reduced due to dirt.
Since the roof is a place that is difficult to check by yourself, please feel free to consult us if you have any concerns.
Can you also handle renovations for roofs that already have solar panels installed?
Yes, we can. Kakeru Koumuten can remove and reinstall solar panels in-house, allowing us to remove the panels, perform roof overlay (cover method) or re-roofing, and then reinstall them consistently. The removed panels can be stored in our own warehouse.
For costs, please refer to the solar panel removal and water heater removal pricing page.
If you are looking for a solar panel installation company in Yokosuka City, please consult Kakeru Koumuten
Our company handles many exterior renovations, including solar panels, roof work, and exterior wall work in Yokosuka City.
We receive requests from a wide range of customers, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received positive feedback from many customers.
We continue to update our annual construction achievements and will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and re-roofing but also partial roof repairs, exterior painting, and exterior cover installations.
We are also happy to handle small jobs like partial repairs and rain gutter cleaning!
In urgent cases like water leakage work, we may be able to provide emergency measures without setting up scaffolding, as long as safety can be ensured, so please consult with us!
“I want to know about recommended solar panels”, “I want to keep costs as low as possible”, “I just want an estimate for now”, we will provide optimal solutions for your specific requests.
We will never propose unnecessary work that prioritizes profit!
We always stand in the customer’s position and will propose the best construction plan!
We are confident that we will not be outdone in terms of cost, quality, and planning for exterior work compared to other companies!
We welcome competitive quotes because we are confident!
Estimates are completely free, and if our company is found to be inferior to others, feel free to decline!
Characteristics of Yokosuka City and Points for Solar Work
Yokosuka City is a core city located in the southeastern part of Kanagawa Prefecture, within 50 km of Tokyo.The city is characterized by hilly and mountainous terrain (Kamimachi Hills, Ookusuyama Range, Takeyama Range) with elevations around 100-200m, and there are few wide flat areas, and the coastline also has variations. We have summarized the characteristics of Yokosuka City’s terrain and climate, as well as points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Yokosuka City and points for solar work
■ In cities with many hills and mountains, pay attention to scaffolding and transportation routes on sloped or uneven sites
Yokosuka City is characterized by its many mountains and hills, with few wide flat areas. In sloped areas or sites with elevation differences, careful planning of scaffolding and the delivery routes for equipment and materials such as panels and storage batteries may be necessary. Kakeru Koumuten Co., Ltd. plans scaffolding tailored to the site even when there are elevation differences, using its own scaffolding team and materials. Additionally, for sites close to mountains and trees, it is important to pay attention to the effects of shadows and the decrease in power generation due to fallen leaves and dirt, and we can also handle cleaning of solar panels and rain gutters with specialized brushes.
■ For locations near the sea, confirm the installation site and equipment specifications in advance
The northeastern part of Yokosuka City is described as a drowned valley of a ria coastline, with the west coast featuring many coastal erosion areas, while the rest is generally composed of sandy beaches and capes. When installing in locations near the sea, it is important to confirm in advance whether the panels, power conditioners, and storage batteries meet the manufacturer’s installation conditions (such as whether they are in areas subject to salt damage specifications). If you want to use electricity during a power outage, please consider installing a storage battery.
■ Prepare for rainfall by confirming waterproofing details and equipment placement
According to city documents, Yokosuka City tends to have many days without precipitation and low rainfall, while the occurrence of rainfall exceeding 50mm in one hour is somewhat frequent. To prepare for heavy rain in a short period, it is important to check the waterproof treatment of the panel fixing parts and the surrounding environment of the installation site for equipment such as storage batteries and power conditioners (e.g., whether it is a place where water tends to accumulate) before installation. Please check the information for your area on hazard maps and consult us about the installation site.
■ Because Yokosuka City has varying conditions in hilly, mountainous, and coastal areas, we check roofs and sites individually through on-site surveys
In Yokosuka City, where the conditions differ between sites close to hills and those near the sea, the type and age of roofs, as well as sunlight exposure, vary from house to house. At Kakeru Koumuten Co., Ltd., we will confirm the type and condition of the roof and the situation of the site before installation, and propose methods for securing the panels, waterproofing details, and scaffolding plans.
■ The annual sunshine hours in neighboring Yokohama City is about 2,018 hours
According to the Japan Meteorological Agency’s average values (1991-2020), the annual sunshine hours in Yokohama City, which is adjacent to Yokosuka City, is about 2,018 hours. Monthly, August (about 206 hours) has the most, while June during the rainy season (about 136 hours) has the least.
Power generation varies by season and location, so conducting annual power generation simulations and selecting the capacity of storage batteries to match the times of high electricity usage is key.
Our company is based in Kanagawa Prefecture and handles many exterior construction and solar projects in Yokosuka City.
We are happy to assist with partial roof repairs such as roof overlay work, roof replacement, and leak repairs, as well as other repairs! Please feel free to consult us about any sudden troubles!
Service Area in Yokosuka City
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Yokosuka City
Yokosuka City, Akiya / Yokosuka City, Ashina / Yokosuka City, Abekura / Yokosuka City, Awata / Yokosuka City, Anjindai / Yokosuka City, Ikegami / Yokosuka City, Ikedacho / Yokosuka City, Inaokacho / Yokosuka City, Furuidocho / Yokosuka City, Iwatoko / Yokosuka City, Uchikawa / Yokosuka City, Uchikawa Shinden / Yokosuka City, Uraga / Yokosuka City, Uragaoka / Yokosuka City, Uragami Dai / Yokosuka City, Uragokocho / Yokosuka City, Kamimachi / Yokosuka City, Ota Kazu / Yokosuka City, Otaki Cho / Yokosuka City, Otsucho / Yokosuka City, Oyabe / Yokosuka City, Ogawacho / Yokosuka City, Ogino / Yokosuka City, Oohama Higashimachi / Yokosuka City, Oohama Minamimachi / Yokosuka City, Oohama Honmachi / Yokosuka City, Oohama Cho / Yokosuka City, Obara Dai / Yokosuka City, Kanaya / Yokosuka City, Kamoi / Yokosuka City, Kinugasa Sakaecho / Yokosuka City, Kinugasa Cho / Yokosuka City, Kogokucho / Yokosuka City, Kusunokigawacho / Yokosuka City, Kubisato / Yokosuka City, Kumura / Yokosuka City, Kurihama / Yokosuka City, Kurihama Dai / Yokosuka City, Green Heights / Yokosuka City, Kofuudai / Yokosuka City, Koyasu / Yokosuka City, Koyabe / Yokosuka City, Sakamoto Cho / Yokosuka City, Sakuragaoka / Yokosuka City, Sazima / Yokosuka City, Sazima no Oka / Yokosuka City, Sano Cho / Yokosuka City, Sawara / Yokosuka City, Sarushima / Yokosuka City, Shioiricho / Yokosuka City, Shiomidai / Yokosuka City, Shonan Kokusai Mura / Yokosuka City, Shonan Takatore / Yokosuka City, Shinminatocho / Yokosuka City, Shinmei Cho / Yokosuka City, Sugarayatani / Yokosuka City, Tanaura Izumicho / Yokosuka City, Tanaura Daisaku Cho / Yokosuka City, Tanaura Minatocho / Yokosuka City, Tanaura Cho / Yokosuka City, Takatori / Yokosuka City, Take / Yokosuka City, Tanatodai / Yokosuka City, Tsukui / Yokosuka City, Tsurugaoka / Yokosuka City, Tomari Cho / Yokosuka City, Nagai / Yokosuka City, Nagauracho / Yokosuka City, Naga Saka / Yokosuka City, Nagasawa / Yokosuka City, Nagase / Yokosuka City, Natsushima Cho / Yokosuka City, Nishi Uraga / Yokosuka City, Nishi Itsubimi Cho / Yokosuka City, Negishi Cho / Yokosuka City, Nobi / Yokosuka City, Highland / Yokosuka City, Hakozaki Cho / Yokosuka City, Hashirimizu / Yokosuka City, Hamamidai / Yokosuka City, Hayashi / Yokosuka City, Higashi Uraga / Yokosuka City, Higashi Itsubimi Cho / Yokosuka City, Hikari no Oka / Yokosuka City, Hinode Cho / Yokosuka City, Heisaku / Yokosuka City, Fukatadai / Yokosuka City, Fujimicho / Yokosuka City, Futaba / Yokosuka City, Funakura / Yokosuka City, Funakoshicho / Yokosuka City, Heisei Cho / Yokosuka City, Heiwa Dai / Yokosuka City, Itsubimi ga Oka / Yokosuka City, Bouyodai / Yokosuka City, Honmachi / Yokosuka City, Umabori Kaigan / Yokosuka City, Umabori Cho / Yokosuka City, Midorigaoka / Yokosuka City, Minato ga Oka / Yokosuka City, Miharu Cho / Yokosuka City, Miyukihama / Yokosuka City, Morizaki / Yokosuka City, An’yura Cho / Yokosuka City, Yamashina Dai / Yokosuka City, Yamanaka Cho / Yokosuka City, Yoshii / Yokosuka City, Yoshikuracho / Yokosuka City, Yonegahama Dori / Yokosuka City, Wakamatsu Cho / Yokosuka City, Wakamiya Dai
・Trust Kakeru Koumuten for exterior wall painting in Yokosuka City!
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・Trust Kakeru Koumuten for exterior renovations in Yokosuka City!
・Kakeru Koumuten Co., Ltd. project achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. service menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・Explaining the importance of getting multiple estimates and points to compare!
・Top 12 solar power generation manufacturers! Features and selection tips included!
・What are the installation costs for solar power generation? Comprehensive tips to reduce costs!
・What are the best locations for solar power installation? Points for selecting installation sites included!
・Check out our solar power generation estimates here!
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contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
