Leave Your Solar Panel Installation Work in Isehara City, Kanagawa Prefecture to Kakeru Koumuten Co., Ltd.!
For solar panel and storage battery installation in
Isehara City, Kanagawa Prefecture,
trust Kakeru Koumuten!
Kakeru Koumuten is a specialized exterior renovation company headquartered in Aoba Ward, Yokohama City.
As a company strong in roofing work, we are entrusted withsolar panel installation and storage battery installation considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Isehara City”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Isehara 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 do not regret your solar panel installation, we recommend obtainingthree or so estimates!
Table of Contents (Tap to Open/Close)
- Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Isehara City, Kanagawa Prefecture
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Isehara 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 Installer in Isehara City, Kanagawa Prefecture
- 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 Isehara City
- If You’re Looking for a Solar Panel Installer in Isehara City, Contact Kakeru Koumuten
- Characteristics of Isehara City, Kanagawa Prefecture and Points for Solar Installation
- Service Area in Isehara City, Kanagawa Prefecture
Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Isehara City, Kanagawa Prefecture
The reasons why we are entrusted with solar panel installation by customers in Isehara City, Kanagawa Prefecture include
one reason being that Kakeru Koumuten has a base in Kanagawa Prefecture,
and our unique strengths in solar panel installation that cannot be imitated by other companies, which 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 other than solar panel installation!
Troubles such as leaks caused by solar panel installation may be due to insufficient checks on the roof and waterproofing at the installation site.
Even if you are knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside your expertise, so caution is necessary.
It’s reassuring to have someone knowledgeable about the roof to avoid maintenance issues and troubles 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 troubles after solar panel installation!
2.Facilities Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. has prepared the following warehouses and material storage areas to provide low-cost, high-quality solar construction and exterior renovation.
We have established five bases centered around Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding according to the construction conditions, allowing us to assemble scaffolding in-house.
By not outsourcing scaffolding work and using our own scaffolding team, we can also cut costs for scaffolding work.
We have scaffolding materials for approximately 50 single-family homes!
In the residential areas of Isehara City, where the terrain changes from hills to plateaus to plains, our in-house scaffolding team plans 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 can purchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we can respond 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 the roofing materials!
We can also provide simulations for 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 Kakeru Koumuten handle everything from inquiries to project completion in a consistent manner, we can keep costs down and provide high-quality roof renovations.
Additionally, one representative will handle everything from the estimate to the completion of the work.
Since the same person is responsible throughout the process, communication can be smooth.
We can perform consistent in-house construction from temporary scaffolding installation, exterior wall painting, to roof renovations!
4. Various Permits and Skilled Workers
We have obtained permits for construction work and industrial waste collection and transportation!
We also have nationally certified sheet metal workers and painting specialists, and we are confident in our construction techniques.
We can also handle large-scale roofing projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation work, we also provide our own construction warranty (leakage warranty)!
(The construction warranty 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 unless roof renovations are performed. The construction warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary depending on the warranty content.)
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 drones to assist!
During leak investigations, we can also conduct surveys using a thermal imaging camera.
If the power generation of solar panels decreases due to dirt, we can provide cleaning with a specialized brush.
We will respond according to our customers’ wishes.
7. Human Resource Development
To improve skills, we create various roof models and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly conduct technical training to ensure that each staff member 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 construction guidebook” and “profit and loss simulations” that consider loan interest rates and electricity costs.
Profit and loss simulations can be created for projected cumulative profits and losses over 20 to 30 years.
For customers who are not familiar with solar construction, we compile materials that clearly outline 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, which specializes in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Age | The fixing method varies depending on the roofing materials such as slate, tiles, metal roofs, and flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest roof renovation first. |
| 2. Condition of Substrate and Waterproof Sheet | If the sheathing or roofing (waterproof sheet) under the roofing material is damaged, it will affect the fixing strength of the fittings 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, will affect the amount of electricity generated. We can create a layout diagram from the drawings and the site, and you can confirm it with a power generation simulation. |
| 4. Shape of the Roof and Installable Area | The number of panels (installation capacity) that can be placed depends on the shape and size of the roof. Since the number of installable panels varies depending on the size of the panels, we will compare based on the total output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will check whether the method involves drilling holes in the roofing material for fixing or using fittings to secure the roofing material. The fixing method varies by technique, so please confirm 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 placed on it. After investigating the existing roof, substrate, and load-bearing capacity, switching to lighter roofing materials may also be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will confirm 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 will also affect the cost. |
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 fix to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the investigation results, there may be methods to replace with lighter roofing materials before installation. |
| Metal Roof (Horizontal and 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, methods that do not drill holes may be available. |
| Flat Roof / Rooftop | Fixed by installing a frame | Type and deterioration status of the waterproof layer, waterproofing around the frame. Consider in conjunction with the timing of waterproofing work. |
If you perform roof renovations 10 to 20 years after installation, additional costs for the removal and reinstallation of solar panels will apply. If the roof is deteriorating, renovating to a highly durable roofing material before installation may help reduce costs in the long run.
Kakeru Koumuten Co., Ltd. specializes in roofing work and can also handle the removal and reinstallation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Isehara City, Kanagawa Prefecture
PossibleSubsidies and Grants
When introducing solar panels or storage batteries in Isehara City, there is a possibility of being eligible for programs from the “National Government,” “Kanagawa Prefecture,” and “Isehara City.”
The following information is based on the official pages of each program as of October 6, 2026. The application status may change depending on the budget and application period, 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 |
|---|---|---|---|
| Isehara City “Reiwa 8 Fiscal Year Existing Housing Solar Power Generation Equipment Installation Subsidy” | New installation of solar power generation equipment in existing homes (unused items). Storage batteries are only eligible if applied for together with solar power generation equipment. Installations started before the grant decision are not eligible. Apartment buildings are not eligible. | Solar: 30,000 yen per kW (maximum 150,000 yen) Storage battery: Flat 50,000 yen |
As of June 9, 2026, the budget limit has been reached, and applications are closed (currently, applications cannot be made). The budget was for 20 cases, and the project completion deadline was March 15, 2027. |
| Isehara City “Reiwa 8 Fiscal Year Energy-Saving Housing Support Subsidy” | Individuals registered as residents in the city who are implementing ZEH or insulation window renovations (must have received grant decision from the national or prefectural government). Standalone installation of solar panels or storage batteries is not eligible. | ZEH: 100,000 yen Insulation window renovation: Either the amount after deducting the national and prefectural subsidy or 100,000 yen, whichever is lower. |
As of September 10, 2026, the budget limit has been reached, and applications are closed. |
| Kanagawa Prefecture “Reiwa 8 Fiscal Year Kanagawa Prefecture Residential Solar Power Generation and Storage Battery Installation Subsidy” | For single-family homes or multi-family homes in the prefecture, installing both solar power generation and storage batteries in earthquake-resistant homes. Applications must be made by the individual, and construction must start after the grant decision. | Solar: 70,000 yen/kW Storage battery: 150,000 yen/unit |
Phase 1: May 11, 2026 – June 30, 2026 Phase 2: September 7, 2026 – September 30, 2026 (first-come, first-served) Phase 2 has reached its application deadline. Please check the prefecture’s official page for future applications. |
| National “DR Home Storage Battery Project” (Reiwa 7 Fiscal Year Supplement) | New installation of home storage systems that can be utilized for DR (demand response) with registered products. | Calculated based on an initial effective capacity of 34,500 yen per kWh (subsidy rate within 3/10; maximum 600,000 yen per application). | As of May 29, 2026, the budget has been reached, and public recruitment is closed (currently, applications cannot be made). |
| 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 the structure; applications cannot be made for just the installation of storage batteries. Solar panels are not included as eligible facilities. | Storage battery: 96,000 yen/unit | Ends as soon as the budget limit is reached. Please check the official site for application status. |
| Kanagawa Prefecture “Reiwa 8 Fiscal Year Kanagawa Prefecture Self-Consumption Renewable Energy Installation Subsidy” | Corporations and individual business owners filing blue returns (individual residences are not eligible). Solar power must have a generation capacity of 10kW or more, facilities for business use, and equipment not certified under FIT/FIP, etc. | Solar power: 80,000 yen/kW, etc. Storage systems: 50,000 yen/kWh (up to 5 million yen) |
Application closed on September 3, 2026 (when the application amount reached the budget amount) |
The solar power subsidies in Isehara City and the residential subsidies from Kanagawa Prefecture require not only the acceptance of applications but also construction to commence after receiving “grant approval”. If construction begins beforehand, it will be ineligible. The city’s program has reached its budget limit and is no longer accepting applications, but please check the city’s official page for information on potential resumption within the fiscal year or future applications. It is not guaranteed that subsidies will be granted upon application, so please confirm before contracting or starting construction.
Kakeru Koumuten will provide guidance on eligibility conditions and business requirements for each program after confirming them.
Isehara City “Reiwa 8 Year Existing Residential Solar Power Generation Equipment Installation Subsidy”
Isehara City provided subsidies for those installing new solar power generation equipment in existing homes. For purchases, the eligible applicants are homeowners (or residents with the owner’s consent), while for leases, registered businesses under the “Kanagawa Solar Bank System” were eligible.
The subsidy amount is 30,000 yen per kW for solar power generation (up to 150,000 yen), and a flat 50,000 yen for storage batteries, and storage batteries are only eligible if applied for together with solar power generation equipment. The budget was for 20 cases, and applications had to be submitted before commencing construction, with construction starting only after receiving grant approval.
However, the budget limit was reached at 15:25 on June 9, 2026, and application acceptance has ended. There are no plans for resumption noted on the city’s official page, so please check the city’s official page (Environmental Measures Division) for future applications.
👉 Click here for Isehara City’s official page
Isehara City “Reiwa 8 Year Energy-Saving Housing Support Subsidy” (ZEH & Insulated Window Renovation)
Isehara City provided subsidies for individuals registered as residents in the city who were constructing, purchasing, or renovating ZEH (Net Zero Energy Houses) or conducting insulated window renovations. It was a condition to have received grant approval from the national or Kanagawa Prefecture, with subsidy amounts being 100,000 yen for ZEH and either the amount after deducting national and prefectural subsidies for insulated window renovations or 100,000 yen, whichever is lower.
This program does not solely target the installation of solar panels or storage batteries. Additionally, the budget limit was reached on September 10, 2026, and application acceptance has ended.
👉 Click here for Isehara City’s official page
National Subsidy “DR Home Storage Battery Project (Support Project for Home Storage System Installation for DR Resource Introduction)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program is aimed at those who are introducing a new registered energy storage system that can be utilized for demand response (DR). 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 limit 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 supplementary budget for fiscal year 2025 reached its application budget on May 29, 2026, and the public recruitment has ended (the previous fiscal year 2024 supplementary budget also ended on July 2, 2025). Currently, applications cannot be made, so please check the official website for future public recruitment.
Furthermore, there are currently no subsidies confirmed by the government specifically for the installation of solar panels on existing homes.
👉 Click here for the official DR home battery project website
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Housing Solar Power Generation and Storage Battery Installation Subsidy”
In Kanagawa Prefecture, subsidies are provided for those who introduce both “solar panels” and “storage batteries” to their homes.
The details of the subsidy are 70,000 JPY per kW of solar power generation output and 150,000 JPY per storage system.
For example, if you introduce a 4 kW solar panel and one storage battery, the subsidy amount would be calculated as 4 kW × 70,000 JPY + 150,000 JPY = 430,000 JPY.
The energy storage system must be a registered product, if construction begins before the grant decision, it will not be eligible, and the application must be made by the individual (applications by contractors on behalf are not allowed). Additionally, the eligible homes must be those that ensure seismic performance. The compatibility with other subsidy systems may vary by program, so please be sure to check.
In fiscal year 2026, the first phase (May 11 to June 30) and the second phase (September 7 to September 30, first-come-first-served) were conducted, and the second phase has reached its application deadline. For future recruitment, please check the official page of Kanagawa Prefecture.
👉 Click here for the official page of Kanagawa Prefecture
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Self-Consumption Type Renewable Energy Installation Subsidy” (for businesses)
Kanagawa Prefecture is also implementing subsidies 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 homes is not eligible.
Conditions include that solar power generation must have an output of 10 kW or more, supply electricity to business facilities within the prefecture, and be equipment that does not receive FIT or FIP certification.
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 limit of 5,000,000 yen).
As the application amount reached the budget amount for the fiscal year 2026, the recruitment was closed on September 3, 2026.
Businesses considering the installation of solar panels on commercial buildings in Isehara City should check the official Kanagawa Prefecture page for the next recruitment.
👉 Click here for details
Solar Panel Installation & Storage Battery Installation Price List
⇧ Service Menu | Click here for costs related to solar panel removal and water heater removal
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and storage batteries should be checked separately for “Equipment Costs (Equipment Price)” and “Construction Costs.”
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Concept of Installation Capacity (kW) and Storage Battery Capacity (kWh)
The installation capacity of solar panels is determined by “the output of one panel (W) × number of panels”, with the unit being kW (kilowatt). The battery is compared in terms of the amount of electricity it can store, expressed in kWh (kilowatt-hour).
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 a layout diagram from the blueprints and on-site survey to present the installation capacity.
On our pricing page, we list 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 the length of wiring, 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 Confirmation)
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 specified. |
| 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 a power outage (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of the hardware suitable for the roofing material and the method of securing it (whether it is a method that drills holes or a method that clamps to secure). |
| 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 the fixed points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | How much support is included for applications to the power company, certification applications for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If roof work and exterior painting are done simultaneously, check that the same scope and quantity are not double counted. |
| 9. Removal and Disposal | Whether the removal of existing solar water heaters or old panels and disposal costs for waste materials are included. |
| 10. Tax Classification and Warranty | Whether the price includes tax or not, conditions under which additional costs may arise, and details and duration of manufacturer and workmanship warranties. |
If the capacities are different, the prices and power generation amounts will also change. Kakeru Koumuten Co., Ltd. welcome comparisons of estimates, so if you bring estimates from other companies, we will explain the differences 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 get 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)!
Examples 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 range |
| Base Mounting Hardware Used |
| Niigata Manufacturing / Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Arrangement |
| Fixed by gripping the horizontal metal roof with catch type hardware (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the grant being provided, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant 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 grants are available, and I would like to know how much can be provided. |
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 have also understood the expected amount of the grant, and we explained this to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Isehara City, Kanagawa Prefecture
There are many solar panel installation companies that serve Isehara City, Kanagawa Prefecture, and you may be unsure which company to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s confirm the following 4 points:
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and aftercare maintenance
● Obtain estimates from multiple companies (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 company.
Have knowledge not only about solar panels but also about roofs
Improper installation of solar panels can be caused by a lack of knowledge and verification 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 verification of roofs and waterproofing
・Solar panels installed on a deteriorated roof causing leaks
・Solar panels installed on a roof with a short lifespan, requiring renovations for removal and reinstallation within a few years
・Misjudgment of the type of waterproofing leading to incorrect processing and resulting in leaks
and more
When installing solar panels, understanding the condition and type of the existing roof allows you to avoid unnecessary expenses and unforeseen troubles.
▶ Go to “Roof Verification Before Installing Solar Panels” within this article
Confirm the existence of warranties and aftercare maintenance
When choosing a solar installation company, let’s confirm the existence of warranties. It is important to check not only the number of years but also the scope of coverage, disclaimers, and cost conditions.
Solar panels and battery storage units come with manufacturer warranties, but also confirm whether there is a workmanship warranty in case leaks occur after installation!
For companies that offer workmanship warranties, if leaks occur after installation, they may be able to respond under the warranty, provided it is within the warranty period and conditions.
Additionally, some contractors offer after-sales service separate from warranties, so be sure to check if the contractor you are considering has after-sales service.
Changes or damage on the roof may occur in areas that are not visible, so there is a possibility that customers may not notice them themselves.
By conducting inspections during after-sales maintenance, we can easily prevent major repairs or failures by detecting abnormalities early!
Kakeru Koumuten Co., Ltd. provides a 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 conduct after-sales maintenance and send out DM every year!
Please check the DM, and if you wish, we will visit you for after-sales maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, be sure to 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 services at a lower price from your preferred contractor, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check the following:
“Check the items in the estimate”
“Type of solar panel”
“Warranties and after-sales services”
Make sure to compare these details carefully! If the rank of auxiliary materials is low or if steps are skipped, costs can be reduced, so avoid making decisions based solely on price!
▶ Go to “Breakdown of Installation Capacity and Equipment/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 the Kanagawa Prefecture housing subsidy, where contractors cannot apply on behalf of the client, it is reassuring to have a contractor who can assist with the preparation of necessary documents and the flow of procedures.
Complete the procedures specified for each system (for the prefectural housing subsidy, this includes the grant decision) before proceeding with the construction!
For the prefectural housing subsidy, after the construction is completed, a performance report must be submitted, and the grant will be provided after review! (The flow of procedures varies by system)
▶ To “Subsidies and Grants That May Be Applicable in Isehara City” in this Article
Benefits of Introducing Solar Power Equipment
The benefits of introducing solar panels are summarized in the following 5 points!
Benefit 1: Economic Advantage
The biggest advantage of introducing solar panels is the economic benefit!
Although the selling price of electricity has decreased compared to 10 years ago, you can gain benefits by reducing the electricity you buy from power companies by consuming the electricity you generate yourself!
As electricity prices rise, the ability to cover your consumption with solar power becomes attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
For residential use (under 10kW), the selling price (FIT) from certifications after October 2025 is set at “24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year.” 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), making the combination with a storage battery a viable option.
👉 Ministry of the Environment | For purchase prices, periods, etc., click here
Benefit 2: You Can Utilize Subsidies!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the criteria, you may be able to utilize subsidies!
Reducing the actual burden amount through subsidies is a significant advantage!
In the case of Isehara City, there may be subsidies available from the city and Kanagawa Prefecture, so please check the latest application status.
Benefit 3: Environmentally Friendly!
Solar power generation has low carbon dioxide emissions and reduces 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 like power conditioners may have operational noise.)
Benefit 4: Heat Insulation Effect Expected!!
By installing the panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, it can help reduce the temperature rise of the roof, providing a heat insulation effect!
(Note that this does not improve the building’s insulation performance itself.)
Benefit 5: Electricity can be used even 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 reinstalling the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing 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 simulations before introducing solar panels!
Point 2: The risk of leaks increases 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 treatment at the fixed points becomes crucial.
If the method involves making holes in the roof, there will inevitably be a risk of leaks.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, one option is to replace the roofing material with a metal roof and secure the solar panels using the catch method. (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 metal fittings for horizontal metal roofs
Point 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-bearing capacity, switching to a lighter 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!
How to Choose 1: Compare by 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 the more power generated, the better!
The size and output of solar panels vary by manufacturer.
For example, a 350W output panel and a 400W output panel may seem like the higher output panel is better at first glance.
However, if the size of the panel does not fit well with the roof, there may be cases where “20 panels of 350W can be installed” and “15 panels of 400W can be installed,” resulting in different numbers of panels that can be installed on the same roof due to size differences.
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 one 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 the roof’s orientation, slope, and shading.
How to Choose 2: Compare by Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases over 10 and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output guarantee value is a standard figure for warranty purposes and does not indicate the actual degradation rate or power generation amount.
By not deciding solely based on initial output and considering the degradation rate, you can choose solar panels without regrets!
How to Choose 3: Compare by 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.
Some manufacturers offer a 30-year output warranty, while others may only offer a 10-year warranty, so it varies!
The longer the warranty, the better, so be sure to check the warranty period and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Isehara City
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Isehara City. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Isehara City, Kanagawa Prefecture?
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.
Guidelines for different capacities are published on the solar panel and storage battery installation pricing page. We will create a layout plan from the drawings and on-site survey and provide a free estimate!
Are there any subsidies available for solar power and storage battery installation in Isehara City?
As of October 6, 2026, the Isehara City “Subsidy for the Introduction of Solar Power Generation Equipment for Existing Homes” (30,000 yen per 1kW of solar power, maximum 150,000 yen; 50,000 yen for storage batteries) has reached its budget limit and is no longer accepting applications as of June 9, 2026. The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power; 150,000 yen per unit for storage batteries) is also approaching the application deadline for the second term of fiscal year 2026, and the national DR home storage battery project has ended its public recruitment.
Since the application status may change, please refer to the subsidy and grant section and consult with us before signing a contract.
Can I apply for subsidies after the construction is completed?
In many programs, procedures must be completed before construction. Both the Isehara City subsidy and the Kanagawa Prefecture subsidy require “commencement of construction after grant approval,” and if the installation is done beforehand, it will not be eligible.
The order of procedures varies by program, so please confirm before signing a contract or starting construction.
Can solar panels be installed on a slate roof? I’m worried about leaks.
Installation is possible on a slate roof, but it requires confirmation of the roof material and substrate condition. The method of securing the panels varies by method, and when securing brackets to the roof material or substrate, waterproofing treatment of the secured areas is crucial.
Kakeru Koumuten is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation and suggest methods such as roof overlay or replacement if deterioration is advanced.
The roof is old. Should I do a roof renovation first?
It depends on the condition of the roof. If a roof renovation is needed within 10 to 20 years after installation, the cost of removing and reinstalling the solar panels will be incurred separately. If the remaining lifespan of the roof is short, renovating to a highly durable roofing material before installation may help reduce total costs.
After confirming the condition of the roof during the on-site survey, please consult us on how to proceed with the installation!
Is it better to install a storage battery together with solar panels?
If you want to use the generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price of electricity will be 8.3 yen/kWh after the fifth year, making it more advantageous to use it in your home rather than selling it.
Additionally, the subsidy in Kanagawa Prefecture requires the simultaneous introduction of solar panels and storage batteries, and the subsidy in Isehara City was also limited to cases where the storage battery was applied for together with the solar power generation equipment. You can compare “solar only” and “solar + storage battery” in the income and expenditure 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, direction, and size of the roof. At Kakeru Koumuten, we create a layout diagram from the drawings and on-site survey, and we will provide you with the installation capacity and power generation simulation.
Isehara City has a terrain that continues from the northwestern Oyama to the southeast with hills, plateaus, and plains, and the shading from surrounding trees and buildings varies from house to house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
In the above construction example (solar panel 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 and installation capacity of the roof.
Please note that additional time is required for subsidies and applications 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 quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides income and expenditure simulations that take into account loan interest rates and electricity prices.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-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 decreases due to dirt.
It can be difficult to check areas on the roof by yourself, so please feel free to consult us if you have any concerns.
Can you also handle renovations of roofs that already have solar panels installed?
Yes, we can. Kakeru Koumuten can detach and reattach solar panels in-house, so we will handle the removal of the panels, perform the roof overlay (cover method) or re-roofing, and then reinstall them all in one go. The removed panels can be stored in our warehouse.
For costs, please see the solar panel removal and installation fee page.
If you are looking for a solar panel installation contractor in Isehara City, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roofing work, and exterior wall work in Isehara City, Kanagawa Prefecture.
We have received requests from many customers, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received great feedback from numerous customers.
We continue to update our construction achievements every year, and we 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 cover installations for exterior walls.
We are also happy to handle small jobs like partial repairs and rain gutter cleaning!
In urgent cases like leak repairs, we may be able to provide temporary measures without setting up scaffolding, as long as safety can be ensured, so please consult us!
“I want to know about recommended solar panels”, “I want to keep costs down as much 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 our customers’ shoes and propose the best construction plans!
We are confident that we will not be outdone in terms of cost, quality, and planning for exterior work compared to other companies!
We are confident, so we welcome competitive quotes!
Estimates are completely free, and if we are found to be inferior to other companies, you are free to decline!
Characteristics of Isehara City, Kanagawa Prefecture, and Points for Solar Work
Isehara City is located almost in the center of Kanagawa Prefecture, with hilly areas, plateaus, and plains extending from the northwest at Mt. Oyama to the southeast.
We have summarized the topography and climate of Isehara City, as well as points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Isehara City and points for solar work
■ A terrain that extends from Mt. Oyama to the plains, with various residential locations
Topography of Isehara City (Official City Site) describes the city as being located at the southeastern edge of the Tanzawa Mountains, with elevation decreasing from the northwest at Mt. Oyama (1,251.7m) to the southeast. Hinata and Minami-no-Miya are hilly areas, while Isehara city center, Okazaki, and Takamori are plateaus, and the Ota area is a flat region at about 10m elevation.
Depending on the area, the orientation of roofs and surrounding environments differ. At Kakeru Koumuten, we will check the shape and orientation of the roof, as well as shadows from surrounding trees and buildings on-site, and explain using layout diagrams and power generation simulations.
■ About one-third of the city area is forested. Roofs near trees should be cautious of falling leaves and dirt
City Introduction (Official City) states that the city covers an area of 55.56 square kilometers, with forests and wildlands accounting for about one-third. In homes close to mountains and trees, falling leaves, dirt, and shadows from trees can affect solar power generation. Kakeru Koumuten Co., Ltd. can provide solar panel cleaning with specialized brushes, as well as rain gutter cleaning.
■ A climate with abundant rainfall and warmth. Waterproofing of roofs is essential
According to the city’s topography introduction page, Isehara City is characterized by a climate with abundant rainfall and warmth. On rainy or cloudy days, power generation decreases, so it is reassuring to check with an annual power generation simulation. Additionally, for roofs where solar panel mounting brackets are installed, the reliability of waterproofing is crucial. Kakeru Koumuten Co., Ltd. specializes in roofing work and will propose methods suited to the type of roof.
■ Check the roof condition according to the age of the building
For homes that have been built for several years, it is important to check the condition of the roofing materials and substrate before installing solar panels. Depending on the condition of the roof, installing them simultaneously with roof renovations can reduce future costs for removing and reinstalling solar panels.
■ Different subsidy systems for business buildings compared to residential ones
When installing on business buildings such as factories, warehouses, stores, and offices, there is a different subsidy system than for households. The Kanagawa Prefecture subsidy for businesses closed applications on September 3, 2026, and the Isehara City subsidy for small and medium-sized enterprises for energy-saving equipment installation does not include solar power or storage batteries, and applications have also closed.
■ Yokohama’s annual sunshine hours are about 2,018 hours
Meteorological Agency’s Average Values (1991–2020) indicate that Yokohama has about 2,018 annual sunshine hours (this is not the value for Isehara City but for observation points within the prefecture). Monthly, August has the most hours, while June during the rainy season has the least.
Power generation varies by season, so it is important to conduct an annual power generation simulation and choose the capacity of storage batteries according to peak electricity usage times.
Our company is based in Kanagawa Prefecture and has extensive experience in exterior construction and solar work in Isehara City.
We are happy to handle partial roof repairs such as roof overlay work, roof replacement, and leak repairs, as well as other repairs! Please feel free to consult us for any sudden troubles!
Service Area in Isehara City, Kanagawa Prefecture
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo.
List of Areas in Isehara City, Kanagawa Prefecture
Awakubo, Isehara City / Ikehashi, Isehara City / Ishida, Isehara City / Isehara, Isehara City / Itado, Isehara City / Utagawa, Isehara City / Osumidai, Isehara City / Oyama, Isehara City / Okazaki, Isehara City / Kasakubo, Isehara City / Kamikasuya, Isehara City / Kamihirama, Isehara City / Kamitani, Isehara City / Kushibashi, Isehara City / Koinaba, Isehara City / Kobe, Isehara City / Koyasu, Isehara City / Sakuradai, Isehara City / Sannomiya, Isehara City / Shimoochiai, Isehara City / Shimokasuya, Isehara City / Shimohirama, Isehara City / Shimotani, Isehara City / Shirane, Isehara City / Suzugawa, Isehara City / Zenba, Isehara City / Takamori, Isehara City / Takamori-dai, Isehara City / Tanaka, Isehara City / Tsubonouchi, Isehara City / Nishitomioka, Isehara City / Numame, Isehara City / Hachiman-dai, Isehara City / Higashi-Otake, Isehara City / Higashi-Tomioka, Isehara City / Higashi-Naruse, Isehara City / Hinata, Isehara City / Mitsukejima, Isehara City
・Exterior wall painting in Isehara City, Kanagawa Prefecture, is entrusted to Kakeru Koumuten Co., Ltd.!
・Roof renovation in Isehara City, Kanagawa Prefecture, is entrusted to Kakeru Koumuten Co., Ltd.!
・Exterior renovation in Isehara City, Kanagawa Prefecture, is entrusted to Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd. construction achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. construction menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・We explain the importance of getting multiple estimates and points for comparison!
・Top 12 solar power generation manufacturers! We also introduce features and selection points!
・What are the installation costs for solar power generation? We thoroughly explain tips to reduce costs!
・What are the best locations for installing solar power generation? We also introduce points for selecting installation locations!
・Here is the introduction to solar power generation estimates!
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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!
