Leave Your Solar Panel Installation in Seya, Yokohama City to Kakeru Koumuten Co., Ltd.!
For Solar Panel and Storage Battery Installation in
Seya Ward, Yokohama,
Kakeru Koumuten is at your service!
Kakeru Koumuten is a company specializing in exterior renovations based in Aoba Ward, Yokohama.
As a company strong in roofing work, we are entrusted withsolar panel and storage battery installations considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Seya Ward”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Seya Ward”
We will also explain the above three points!
Installing solar panels carries risks such as“the occurrence of leaks” and other troubles.
To ensure a satisfactory solar panel installation, we recommend obtainingthree or so estimates!
Table of Contents (Tap to Open/Close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Seya Ward, Yokohama
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Seya Ward
- 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 Seya Ward, Yokohama
- 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 Seya Ward
- If You Are Looking for a Solar Panel Installer in Seya Ward, Contact Kakeru Koumuten
- Characteristics of Seya Ward, Yokohama and Key Points for Solar Installation
- Service Area in Seya Ward, Yokohama
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Seya Ward, Yokohama
The reasons why our company is entrusted with solar panel installation by customers in Seya Ward, Yokohama include
one reason being that Kakeru Koumuten has a base in Yokohama City,
and our unique strengths in solar panel installation that cannot be imitated by other companies
which have received high praise from many customers.
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 Can Also Handle Exterior Renovations Besides Solar Panel Installation!
Troubles such as leaks that occur during solar panel installation may be caused by 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 is reassuring to have knowledge about the roof to avoid maintenance 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 organized the following warehouses and material storage areas to provide low-cost, high-quality solar work and exterior renovations.
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 necessary scaffolding materials for temporary scaffolding based on construction conditions, allowing us to assemble scaffolding ourselves.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also reduce scaffolding construction costs.
We have scaffolding materials for approximately 50 single-family homes!
Even in the residential area of Seya Ward, where rivers and greenery are nearby, our own scaffolding team will plan the scaffolding according to the local conditions.
Material Storage 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, we canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, allowing 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 the roofing materials!
It is also possible to simulate the revenue 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 show the structure, allowing for detailed explanations!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is all work performed by our own team.
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 person in charge does not change, whether it’s sales or construction management, smooth communication is possible.
We can perform everything from temporary scaffolding installation to exterior wall painting and roof renovations in-house!
4. Various Permits and Skilled Workers on Staff
We have obtained construction industry permits and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal workers and painting technicians on staff, and we are confident in our construction techniques.
We are capable of handling large-scale roofing projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty, our solar panel installation work comes with our own workmanship warranty (leakage warranty)!
(The workmanship 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 renovation is performed. The workmanship warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary based on the warranty details.)
Aftercare maintenance is available annually, and we send out notification DM every year.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
We are equipped to handle various roof troubles and situations.
If you cannot access the roof due to height, we can utilize a drone for inspection!
During leakage 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 with a specialized brush.
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 each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
At Kakeru Koumuten Co., Ltd., in addition to “estimates”, “layout diagrams”, and “power generation simulations”, we also provide a “solar installation guidebook” and a “financial simulation” that takes into account loan interest rates and electricity costs.
The financial simulation can be created for projected cumulative income and expenses over 20 to 30 years.
Even customers who are not familiar with solar installations will find our materials easy to understand, including 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 to 30 years.
“Is it okay to install them directly on the current roof?” Checking this before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten Co., Ltd., which specializes in roofing work, has summarized the items to check before installation.
| 1. Type of roofing material and age | The method of securing varies depending on the roofing material, such as slate, tiles, metal roofs, or flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest a roof renovation first. |
| 2. Condition of the substrate and waterproof sheet | If the sheathing or roofing (waterproof sheet) beneath the roofing material is damaged, it will affect the fastening strength and waterproofing. We will also check for 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 power generation. We can create a layout diagram from the drawings and on-site, and you can check it with the power generation simulation. |
| 4. Shape of the roof and available installation area | The shape and size of the roof determine the number of panels (installation capacity) that can be placed. The number of panels that can be installed varies depending on their size, so we will compare based on the total output of the roof. |
| 5. Method of securing and waterproofing details | We will check whether the method involves drilling holes in the roofing material for fastening or using brackets to secure the roofing material. The fastening method varies by technique, so please confirm the waterproofing treatment of the fastening parts during the estimate. |
| 6. Weight of the roof | The roof will become heavier due to the panels. After investigating the existing roof, substrate, and load-bearing capacity, replacing with lighter roofing materials may be an option if necessary. |
| 7. Location of equipment installation 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 costs. |
Securing 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 (cover method) or replacement first. |
| Tile Roof | Fixed with brackets and methods suited to 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 a method to replace with lightweight roofing material 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, a method that does not drill holes may be selectable. |
| 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 carry out roof renovations 10 to 20 years after installation, there will be additional costs for the removal and reinstallation of solar panels. If the roof is deteriorating, renovating to high-durability 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 Seya Ward, Yokohama City
PotentialSubsidies and Grants
When introducing solar panels or storage batteries in Seya Ward, there is a possibility of being eligible for programs from the “National Government,” “Kanagawa Prefecture,” and “Yokohama 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, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| System | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Yokohama City “Yokohama Green Energy Partnership Project (YGrEP)” Fiscal Year 2026 | Yokohama residents installing eligible equipment at their homes. Solar power must be newly installed, and either a storage battery, eco-cute, or electric vehicle must be installed simultaneously or already in place. | Solar Power: 15,000 JPY/kW (up to 4 kW) Storage Battery: 120,000 JPY per case (Refund via cashless points, etc.) |
Participation & Installation Support Application: June 15, 2026 – December 25, 2026 (Application before installation) Installation Completion Application: By January 22, 2027 Ends when budget limit is reached |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Residential Solar Power Generation and Storage Battery Installation Subsidy” | Installation of both solar power generation and storage batteries in residential properties within the prefecture. The application must be made by the individual, and construction must start after the grant decision. | Solar Power: 70,000 JPY/kW Storage Battery: 150,000 JPY/unit |
Phase 1: May 11, 2026 – June 30, 2026 Phase 2: September 7, 2026 – September 30, 2026 (first-come, first-served) Phase 2 is approaching its application deadline. Please check the prefecture’s official page for future applications. |
| National “DR Home Storage Battery Project” (Fiscal Year 2025 Supplement) | New installation of home storage systems using registered products that can be utilized for DR (demand response). | Calculated based on an initial effective capacity of 1 kWh at 34,500 JPY (subsidy rate within 30% and a maximum of 600,000 JPY per application). | The budget was reached on May 29, 2026, and public recruitment has ended (applications are currently not accepted). |
| 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 just the installation of storage batteries. Solar panels are not included as eligible facilities. | Storage Battery: 96,000 JPY/unit | Ends when the budget limit is reached. Please check the official site for application status. |
| Yokohama City “Solar Power Generation Installation Support Subsidy” | Small and medium-sized enterprises and sole proprietors in Yokohama City (residential use is not eligible). There are conditions for the target audience and equipment, such as being self-consumption type equipment. | Solar Power + Storage System: 100,000 JPY/kW (up to 5,000,000 JPY) Solar Power Only: 80,000 JPY/kW (up to 4,000,000 JPY) |
May 1, 2026 – October 30, 2026, 5 PM (first-come, first-served until budget limit is reached) |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Self-Consumption Type Renewable Energy Installation Subsidy” | Corporations and individuals filing blue returns（Personal residences are not eligible）。Solar power must have a generation output of 10kW or more, facilities for business use, and equipment not certified under FIT/FIP, etc. | Solar Power: 80,000 JPY/kW, etc. Storage System: 50,000 JPY/kWh (maximum 5,000,000 JPY) |
Application closed on September 3, 2026 (when the application amount reached the budget amount) |
YGrEP requires a “Participation and Introduction Support Application” before installation, and for Kanagawa Prefecture’s residential subsidies, it is a condition that construction begins only after receiving a “Grant Decision”. If you start installation or construction beforehand, you will be ineligible. The prefecture’s residential subsidies are granted after a performance report and review following the completion of construction. The order of procedures varies by program, and applying does not guarantee a grant, 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.
National Subsidy “DR Home Storage Battery Project (Support Project for Home Storage System Introduction 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 introducing newly registered storage systems that can be utilized for demand response (DR), and in the supplementary budget for fiscal year 2025, the subsidy amount is determined based on a standard amount of 34,500 JPY per initial effective capacity of 1kWh, with a subsidy rate of up to 30% and a maximum of 600,000 JPY per application. There are conditions such as being ineligible if contracted or ordered before the grant decision.
However, the supplementary budget for fiscal year 2025 reached the budget amount for grant applications on May 29, 2026, and the public recruitment has ended (the previous year’s supplementary budget for fiscal year 2024 also ended on July 2, 2025). Applications are currently not possible, so please check the official website for future public recruitment.
Additionally, there are currently no subsidies confirmed 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 Generation 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 1kW of solar power generation output and 150,000 JPY per storage system.
For example, if you install a 4kW solar panel and one storage battery, the subsidy amount calculation would be 4kW × 70,000 JPY + 150,000 JPY = 430,000 JPY.
Conditions include that the storage system must be a registered product, if construction begins before the grant decision, it will be ineligible, and the application must be made by the individual (applications by contractors on behalf are not allowed). It is also possible to combine this with YGrEP in Yokohama City.
For the fiscal year Reiwa 8, the first phase (May 11 to June 30) and the second phase (September 7 to September 30, first-come-first-served) are being accepted, and the second phase is approaching its deadline. For future recruitment, please check the official page of Kanagawa Prefecture.
👉 Click here for the official page of Kanagawa Prefecture
Kanagawa Prefecture “Reiwa 8 Fiscal Year Kanagawa Prefecture Subsidy for Self-Consumption Type Renewable Energy Introduction” (for businesses)
Kanagawa Prefecture is also implementing subsidies for businesses introducing “self-consumption type” facilities that use electricity generated by solar panels.
Eligible applicants are corporations or individual business owners filing blue returns, and individual residential installations are not eligible.
Conditions include solar power generation with an output of 10kW or more, supplying electricity to business facilities within the prefecture, and not being a facility certified under FIT or FIP.
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 Seya Ward should check the official page of Kanagawa Prefecture for the next recruitment.
👉 Click here for details
Yokohama City “Subsidy for Solar Power Generation Introduction” (for businesses)
Yokohama City is implementing a system to subsidize part of the introduction costs for small and medium-sized enterprises and individual business owners within the city for solar power generation facilities and other installations.
Residential solar power generation is not eligible, and for households, the YGrEP below will be the contact point. Businesses installing solar panels on stores, offices, factories, etc., in Seya Ward may have the possibility to utilize this, but merely running a business from home does not guarantee eligibility. It is necessary to confirm the requirements for small and medium-sized enterprises and individual business owners, as well as that the facility is a self-consumption type (facilities aimed at selling electricity are not eligible).
The subsidy amount is 100,000 yen per kW when installing solar power generation and storage systems simultaneously (maximum of 5 million yen), and 80,000 yen per kW for solar power generation only (maximum of 4 million yen).
The application period for the fiscal year Reiwa 8 is from May 1, 2026, to October 30, 2026, at 5 PM, on a first-come-first-served basis until the budget limit is reached. Installation of the equipment and commencement of construction must take place after the date of the grant decision.
For detailed conditions and application methods, please check the official website of Yokohama City.
👉 Click here for the official Yokohama City page
Yokohama City “Reiwa 8 Year Yokohama Green Energy Partnership Project (YGrEP)”
Yokohama Green Energy Partnership (YGrEP) is a project aimed at realizing a decarbonized society.
In Yokohama City, households that participate in YGrEP and install eligible equipment (see eligible equipment below) will receive cashless point rewards. Residents of Seya Ward are also eligible.
◎Eligible Equipment and Reward Amounts◎
● Solar Power Generation Equipment (new installation): 15,000 yen/kW (up to 4kW)
* It is a condition to install or have already installed either a storage battery, eco-cute, or electric vehicle simultaneously.
● Storage Battery: 120,000 yen per unit
● Eco-Cute: 20,000 yen per unit
● Electric Vehicle/Plug-in Hybrid Vehicle (set with solar power generation equipment): 100,000 yen per unit
* It is a condition to install or have already installed the solar power generation equipment simultaneously with the storage battery, eco-cute, or electric vehicle (set).
● Electric Vehicle alone (without solar power generation equipment): 50,000 yen per unit
● Fuel Cell (EneFarm): 30,000 yen per unit
● Solar Heat Utilization System: 50,000 yen per unit
● V2H Charging and Discharging Equipment: 100,000 yen per unit
For example, if you install a 4kW solar panel and a storage battery simultaneously, the calculation for the reward amount will be 60,000 yen for solar power + 120,000 yen for storage battery = a total of 180,000 yen.
The application process is “Participation and Installation Support Application (before installation) → Installation of Equipment → Completion Application”, and equipment installed before the installation support application is not eligible. The participation and installation support application for Reiwa 8 Year will be from June 15, 2026, to December 25, 2026, and the completion application will be until January 22, 2027, and will end once the budget limit is reached.
When selling electricity, only the surplus that cannot be used at home is eligible, and submission of monitoring data such as power generation amounts approximately once a year is also a condition. Additionally, only V2H charging and discharging equipment is eligible for point rewards for businesses.
For information on application methods, combining with national and Kanagawa Prefecture subsidy projects, point rewards, and more, please check the special site here for details and inquiries.
Solar Panel Installation & Battery Installation Price List
⇧Service Menu | For Costs of Solar Panel Installation & Battery Installation, Click Here
⇧Service Menu | For Costs of Solar Panel Removal & Water Heater Removal, Click Here
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and batteries should be confirmed by separating them into “Equipment Costs (Device Costs)” and “Construction Costs”.
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly based on installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and 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 (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 a layout diagram based on the drawings and on-site survey to present the installation capacity.
On our pricing page, we list solar panels as approximately 800,000 JPY to 1,200,000 JPY for 3 to 5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6 to 10 kW. (These are just approximate amounts and may vary based on the length of wiring, scaffolding range, existing roofing materials, and panel layout.)
▶ Installation Menu | Costs for Solar Panel Installation and Battery Installation
Items to Confirm 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) should be listed. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also confirm 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 and secures). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, and whether there is a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at the fixed parts, and whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | How much support is included for applications to the power company, certification 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 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 the contents and duration of both manufacturer and workmanship warranties. |
If the capacities differ, the price and power generation will also change. Kakeru Koumuten Co., Ltd. welcome comparisons of estimates, so if you bring estimates from other companies, we can explain the differences item by item!
Self-Estimate and Profit and Loss Simulator 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 Voices
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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 |
| Base Mounting Hardware Used |
| Niigata Manufactured/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 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 grants, so we explained this to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Seya Ward, Yokohama
There are many solar panel installation contractors available in Seya Ward, Yokohama, and you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s confirm the following four points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and aftercare services
● Obtain estimates from multiple contractors (three companies is a guideline)
● Check if they provide support for subsidy applications
By confirming the above four points, you will be able to choose a reliable contractor.
Knowledge about roofs as well as solar panels
Defective installation of solar panels can sometimes 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 severely deteriorated roof, leading to 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 treatment 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 unexpected troubles.
▶ Go to “Roof Check Before Installing Solar Panels” in this article
Confirm the existence of warranties and aftercare services
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 battery storage units come with a manufacturer’s warranty, it is also important to check whether there is a workmanship warranty in case leaks occur after installation!
For contractors that offer a workmanship warranty, if leaks occur after installation, they may be able to respond under the warranty if it falls 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.
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 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 conduct after-sales maintenance and send out DM every year!
After checking the DM, if you wish, we will visit 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 with the same manufacturer and the same construction 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 desired contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates,
“Check the items in the estimate”
“Type of solar panel”
“Warranties and after-sales services”
and make detailed comparisons to make your judgment! 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
Subsidies may be 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 grant may not be awarded.
For systems like Kanagawa Prefecture’s housing subsidies, where applications cannot be submitted by the contractor and must be done by the individual, 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 must be submitted, and the grant will be awarded after a review process! (The flow of procedures varies by system)
▶ To “Subsidies and Grants That May Be Applicable in Seya Ward” within this Article
Benefits of Introducing Solar Power Equipment
The benefits of introducing solar panels are summarized in the following 5 points!
Benefit 1: Economic Benefits
The biggest advantage of introducing solar panels is the economic benefit!
While 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 fiscal year 2026. After the 5th year, it is often more advantageous to use the electricity at home (self-consumption), making the combination with storage batteries a viable option.
👉 Ministry of Economy, Trade and Industry | 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 conditions, you may be able to utilize subsidies!
Reducing the actual burden amount through subsidies is a significant advantage!
In the case of Seya Ward, you may be eligible for subsidies from Yokohama City’s YGrEP or Kanagawa Prefecture.
Benefit 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.)
Benefit 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, it can help reduce the temperature 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 functionality, you may be able to use electricity from a dedicated outlet during daytime generation.
(Note that 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 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 advance and request a simulation 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 in methods that fix brackets to the roofing material or substrate with screws, waterproofing of the fixed areas is crucial.
In methods that involve 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 fix the solar panels using the catch method. (The catch method has compatibility conditions between the roofing material and brackets, 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 it with a lighter roof may be one 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!
Solar panels come in various sizes and outputs depending on the manufacturer.
For example, a 350W output panel and a 400W output panel may seem at first glance that the higher output panel is better.
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,” leading to different installation capacities on the same roof due to the size difference.
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 just the output of one 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.
How to Choose 2: Compare by 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 value is a standard figure for warranty purposes and does not indicate the actual degradation rate or power generation amount.
By considering the degradation rate along with the initial output, 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.
Regarding the output warranty, some manufacturers offer a 30-year warranty while others provide a 10-year warranty, so it varies widely!
Since a longer warranty is generally better, 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 Seya Ward
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Seya Ward. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Seya Ward, Yokohama 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.
Guidelines for different capacities are published on our solar panel and storage battery installation pricing page. We will create a layout diagram 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 Seya Ward?
As of October 6, 2026, the application period for Yokohama City’s YGrEP (15,000 yen/kW for solar power, up to 4kW; 120,000 yen per case for storage batteries) is ongoing (it will end once the budget limit is reached). The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power; 150,000 yen per unit for storage batteries) is approaching the application deadline for the second phase of fiscal year 2026, and the national DR household 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. For Yokohama City’s YGrEP, “participation and introduction support application” is required before installation, and for Kanagawa Prefecture’s subsidy, “commencement of construction after grant decision” is a condition, so if you install first, you will be ineligible.
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.
It is possible to install on a slate roof, but it is necessary to check the condition of the roofing material and substrate. The fixing method varies by construction method, and for methods that fix brackets to the roofing material or substrate, waterproofing treatment of the fixed parts 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 if deterioration is advanced, we can also propose methods such as roof overlay (cover method) or replacement before installation.
My roof is old. Should I do a 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 on how to proceed with the installation 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 advantageous to use it at home rather than selling it.
Additionally, Kanagawa Prefecture’s subsidy requires the simultaneous introduction of solar panels and storage batteries, and Yokohama City’s YGrEP also has conditions for combinations with storage batteries. You can compare “solar only” and “solar + storage battery” through 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 Seya Ward, residential areas spread near rivers and green spaces, and the shading from neighboring houses and trees varies from one house to another. 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 panels 4.3 kW + storage battery), it took about 3 days. The duration may vary depending on whether roof work is done simultaneously and the shape and installation capacity of the roof.
Additionally, please note that there is a separate period required for applications for subsidies and electricity companies, so please consult us as soon as possible.
What is the current selling price (FIT)?
For residential use (under 10 kW), the selling price from certifications after October 2025 will be 24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year, with the same price applied in 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 considers 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 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.
Since it is difficult to check areas on the roof by yourself, please feel free to consult us if you have any concerns.
Can you renovate a roof that already has 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 all in one process. The removed panels can be stored in our warehouse.
For information on costs, please visit the solar panel removal and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Seya Ward, consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roofing work, and exterior wall work in Seya Ward, Yokohama City.
We receive 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 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 methods.
We are also happy to handle small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide emergency 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 as low as possible”, “I just want an estimate for now”, we will provide the best 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 optimal construction plan!
We are confident that we will not be outdone by other companies in terms of cost, quality, and organization for exterior work!
We welcome competitive quotes with confidence!
Estimates are completely free, and if our company is found to be inferior to others, you are free to decline!
Characteristics of Seya Ward, Yokohama City, and Points for Solar Work
Seya Ward, Yokohama City, is located in the westernmost part of Yokohama City, bordered by Yamato City to the west and Machida City in Tokyo to the north, forming a long, narrow area from north to south.
Below are summarized the characteristics of Seya Ward’s terrain and housing situation, along with points to consider when installing solar panels and storage batteries. (Tap to open)
View the characteristics of Seya Ward and points for solar work
■ A long, narrow area with rivers flowing through
Yokohama City Ward Statistics Overview states that Seya Ward is located in the westernmost part of Yokohama City, with the area being long and narrow from north to south, and five rivers—Sakagawa, Daimon River, Aizawa River, Izumi River, and Akugawa—flowing through the ward. The name of the ward is also derived from “seiya,” which means a narrow valley (Introduction to Seya Ward).
In residential areas close to rivers and green spaces, the direction of roofs and the shadows cast by neighboring houses and trees vary from house to house. Kakeru Koumuten Co., Ltd. creates layout diagrams based on blueprints and the local conditions, and we confirm them with power generation simulations.
■ Areas where urbanization zones and urbanization control zones are adjacent
Basic Data of Seya Ward indicates that the area of the ward is 17.17 km2, with the urbanization zone covering 11.9 km2 and the urbanization control zone covering 5.3 km2. About 30% of the ward’s area is designated as an urbanization control zone, and the green coverage rate is 32.9% (FY 2019), with 101 parks located within the ward.
On roofs near greenery, leaves and dirt can easily accumulate on the panels, which may lead to a decrease in power generation. If there are tall trees nearby, attention is also needed for the shadows cast on the panels. Kakeru Koumuten Co., Ltd. can also provide cleaning of solar panels with specialized brushes and rain gutter cleaning. Please note that there may be different restrictions regarding buildings in urbanization control zones, so please check the zoning of your home in advance.
■ Over half are single-family homes, with a larger average area for owned homes
According to the Ward Statistics Overview (2015 National Census), 53.3% of the housing in Seya Ward consists of single-family homes, while 45.2% are multi-family dwellings. Additionally, the introduction page for Seya Ward states that the average floor area of owned homes (FY 2018) is 103.58 m2, ranking second in Yokohama City after Aoba Ward.
In residential areas with many single-family homes, the capacity that can be installed varies depending on the shape and orientation of the roof and the existing roofing materials. It is important to check the condition of the roofing materials and substrate before installing solar panels, and depending on the condition of the roof, installing them simultaneously with roof renovations can help reduce future costs for removing and reinstalling solar panels.
■ Yokohama’s annual sunshine duration is about 2,018 hours
The Japan Meteorological Agency’s average values (1991–2020) indicate that Yokohama’s annual sunshine duration is about 2,018 hours. Monthly, August has the most sunshine, while June, during the rainy season, has the least.
Power generation varies by season, so conducting annual power generation simulations and selecting battery capacity that aligns with peak electricity usage times are key points.
■ Consideration for residential area rules
In Seya Ward, there are building agreements for Seya Koyodai Residential Area, Yokohama Inner Park, and Marks Springs Casa (not all areas in the ward have the same rules). In regions where there are agreements related to roof installations, it is necessary to check the details in advance.
Our company is based in Yokohama City and handles many exterior construction and solar power projects in Seya Ward, Yokohama.
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 Seya Ward, Yokohama City
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo Metropolis.
List of Areas in Seya Ward, Yokohama City
Aizawa, Seya Ward / Akigawa Nishi, Seya Ward / Akigawa Higashi, Seya Ward / Akigawa Minami, Seya Ward / Higashino, Seya Ward / Higashino Dai, Seya Ward / Oroshimachi, Seya Ward / Kamiseyama, Seya Ward / Kitashin, Seya Ward / Kitamachi, Seya Ward / Gokanmachi, Seya Ward / Shimoseya, Seya Ward / Seyamachi, Seya Ward / Seya, Seya Ward / Takemura, Seya Ward / Chuo, Seya Ward / Nakayashiki, Seya Ward / Hashido, Seya Ward / Futatsubashi, Seya Ward / Hongō, Seya Ward / Mitsukyou, Seya Ward / Minamiseya, Seya Ward / Minamidai, Seya Ward / Miyazawa, Seya Ward / Meguro, Seya Ward
・Trust Kakeru Koumuten for exterior wall painting in Seya Ward, Yokohama!
・Trust Kakeru Koumuten for roof renovations in Seya Ward, Yokohama!
・Trust Kakeru Koumuten for exterior renovations in Seya Ward, Yokohama!
・Trust Kakeru Koumuten for leak repairs in Seya Ward, Yokohama!
・Trust Kakeru Koumuten for waterproofing work in Seya Ward, Yokohama!
・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
・Explaining the importance of comparison estimates and key points!
・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? Key points for site selection included!
・Here is the introduction for 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!
