Leave Your Solar Panel Installation Work in Chofu City, Tokyo to Kakeru Koumuten Co., Ltd.!
For solar panel and storage battery installation in
Chofu City, Tokyo,
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 with solar panel and storage battery installations considering roofs and waterproofing!
“How to Choose a Solar Panel Contractor in Chofu City”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Chofu 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 a satisfactory solar panel installation, we recommend obtaining three or so estimates!
Table of Contents (tap to open/close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Chofu City, Tokyo
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Chofu City
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installation Company in Chofu City, Tokyo
- 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 Chofu City
- If You Are Looking for a Solar Panel Installation Company in Chofu City, Contact Kakeru Koumuten
- Characteristics of Chofu City, Tokyo and Points for Solar Work
- Service Area in Chofu City, Tokyo
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Chofu City, Tokyo
The reasons why our company is entrusted with solar panel installation by customers in Chofu City, Tokyo include
one reason being that “Kakeru Koumuten covers Kanagawa and Tokyo areas”,
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 multiple estimates!
1. We 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 be knowledgeable 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 solar work and exterior renovations at low cost and high quality.
We have established five bases centered in 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 cut costs for scaffolding work.
We have scaffolding materials for approximately 50 single-family homes!
In Chofu City, our own scaffolding team will plan the scaffolding according to the site 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, we canpurchase materials at a lower price!
Additionally, we always have a stock of roofing materials, enabling us torespond quickly in emergencies!
Sorting and transporting waste materials in-house
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior renovation dedicated showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on the roofing materials!
Simulations for potential earnings and installation costs when introducing solar panels are also available!
Since roofing and exterior wall work often accompany each other, we also provide samples of roofing materials and models that illustrate 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 maintaining 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 same person is responsible for sales and construction management, smooth communication is ensured.
We can perform consistent in-house work from temporary scaffolding setup to exterior wall painting and roof renovations!
4. Various Permits Obtained & Skilled Workers on Staff
We have obtained permits for the construction industry and for the collection and transportation of industrial waste!
We also have nationally certified sheet metal and painting technicians on staff, giving us confidence in our construction techniques.
We are capable of handling large-scale roofing projects, such as those for 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 each year.
If you have any questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roof troubles and situations.
Even if we cannot access the roof at high altitudes, we can respond using a drone!
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 also provide cleaning with a specialized brush.
We will respond according to the customer’s wishes.
7. Human Resource Development
We create various roof models for skill improvement and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly provide technical training so that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
At Kakeru Koumuten Co., Ltd., we provide not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar installation guidebook” and a “financial simulation” that takes into account loan interest rates and electricity costs.
The financial simulation can project cumulative income and expenses over 20 to 30 years.
We compile easy-to-understand materials that include important points and disadvantages for customers who may not be familiar with solar installations!
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.
It is crucial to confirm before installation whether it is safe to place them directly on the current roof, as this is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten Co., Ltd., which specializes in roofing, has summarized the items to check before installation.
| 1. Type of roofing material and age | The method of securing the panels varies depending on the roofing material, such as slate, tile, 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 can affect the fastening strength and waterproofing. We also check for any signs of leaks. |
| 3. Orientation, slope, and shadows of the roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, can affect power generation. We create a layout diagram from the drawings and the site, and you can confirm it with the power generation simulation. |
| 4. Shape of the roof and available installation area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. The number of panels that can be installed varies depending on their size, so we compare based on the total output of the roof. |
| 5. Method of securing and waterproofing details | We check whether the panels will be secured by drilling holes in the roofing material or by using brackets to grip the roofing material. The method of securing 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 also be an option if necessary. |
| 7. Location of equipment installation and wiring | We check the installation locations for the power conditioner and storage battery, as well as the wiring route to the distribution board. The length of the wiring also affects costs. |
Securing Methods and Checkpoints by Roofing Material
| Roof Material | Main Fixing Method | Pre-installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (methods such as fixing brackets with screws to the roofing material and substrate) | Waterproof treatment of fixed parts, cracks and deterioration of slate, condition of substrate. If deterioration is advanced, consider roof overlay (cover method) 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 roofing material (depends on the combination of roofing material and brackets) | Whether the roofing material and brackets are compatible, installation conditions from the roofing 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, there will be additional costs for the removal and reinstallation of solar panels. 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 Chofu City, Tokyo
Potential Subsidies and Grants in Chofu City, Tokyo
If you are introducing solar panels or storage batteries in Chofu City, Tokyo, there is a possibility that you may be eligible for programs from “the national government,” “Tokyo,” and “Chofu City.”
The following information is based on the official pages of each program as of October 7, 2026. The application status may change depending on the budget and recruitment 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 |
|---|---|---|---|
| Tokyo Metropolitan Government “Reiwa 8 Year Household Solar Power Generation Promotion Project” (Cool Net Tokyo) | A system of less than 50kW with newly installed certified solar modules on residential properties within the city. Pre-application before installation is required. | Existing homes: 150,000 JPY/kW for 3.75kW or less (maximum 450,000 JPY), 120,000 JPY/kW for over 3.75kW New homes: 120,000 JPY/kW for 3.6kW or less (maximum 360,000 JPY), 100,000 JPY/kW for over 3.6kW (Additional costs for mounting frames, waterproofing work, and renovation defect insurance, etc.) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 to March 30, 2029 |
| Tokyo Metropolitan Government “Reiwa 8 Year Household Storage Battery Promotion Project” (Cool Net Tokyo) | New installation of storage batteries in residential properties within the city, and must be SII registered equipment. This project is intended for simultaneous installation with solar power, but applications can be made for storage batteries alone. Pre-applications after October 1, 2026 will only be eligible for SII registered products for Reiwa 8. | Storage battery package: 100,000 JPY/kWh (maximum 1,200,000 JPY per household) Expansion of storage battery units: 60,000 JPY/kWh (maximum 720,000 JPY per household) (Additional incentives for participation in DR demonstrations, etc.) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 |
| Chofu City “Subsidy for Introduction of Residential Renewable Energy and Energy-Saving Equipment” Reiwa 8 Year | Owners of individual or mixed-use residential properties within the city (including new constructions) must have paid all overdue city taxes. Solar power generation requires a contract with a power company and certified equipment, while storage batteries must have a charging function from solar power. Applications must be made after installation, within six months from the completion date (must arrive by the deadline). Equipment that has not received subsidies from other municipal programs is eligible. | Solar power generation: The lower of actual expenditure or 20,000 JPY/kW (maximum 100,000 JPY) Storage battery: The lower of actual expenditure or a flat rate of 50,000 JPY |
Application acceptance: From April 1, 2026 to March 10, 2027 (must arrive by the deadline) Due to budget limitations, the program may end before the deadline. Please check the city’s official page for application status. |
| National “DR Household Storage Battery Project” (Reiwa 7 Year Supplement) | New installation of household storage battery systems that can be utilized for DR (demand response) with registered products. | Calculated based on an initial effective capacity of 30,000 JPY per kWh (subsidy rate within 3/10; maximum 600,000 JPY per application) | The budget was reached on May 29, 2026, and the 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 renovation of windows (openings) and the structure; applications cannot be made for the installation of storage batteries alone. Solar panels are not included as eligible facilities. | Storage Battery: 96,000 JPY/unit | Ends as soon as the budget limit is reached. Please check the official website for the application status. |
In Tokyo, a pre-application before installation is required for the subsidy, and starting the construction beforehand may result in ineligibility. In Chofu City, the subsidy is a post-application after installation completion, which must be submitted within 6 months from the completion date (must arrive by this date), and due to budget limitations, it may end before the deadline. In both cases, it is necessary to meet the eligibility criteria and conditions, and applying does not guarantee approval. For combined use with national and Tokyo subsidies, please check the official pages of each program. Procedures differ for each program, so please confirm before contracting and starting construction.
Kakeru Koumuten will guide you on the eligibility conditions for each program after confirming them.
Tokyo “Reiwa 8 Fiscal Year Household Solar Power Generation Promotion Project”
Tokyo is providing subsidies for those installing solar power generation systems in residential homes through Cool Net Tokyo. The target is systems using certified solar cell modules installed newly in residential homes or on their premises, with a capacity of less than 50kW. A pre-application before installation is required.
For existing homes, the subsidy amount is 150,000 JPY/kW for 3.75kW or less (maximum 450,000 JPY), and 120,000 JPY/kW for over 3.75kW. Additionally, there are extra items for mounting frames, waterproofing work, and renovation defect insurance. The pre-application period is from May 29, 2026, and the application for grants and performance reports is from June 30, 2026, to March 30, 2029. For details on eligible equipment and conditions, as well as budget status, please check the official page.
👉 Cool Net Tokyo | Official page for solar power generation is here
Tokyo “Reiwa 8 Fiscal Year Household Storage Battery Promotion Project”
Tokyo is also providing subsidies for newly installed storage batteries in residential homes. The subsidy amount is 100,000 JPY per kWh for storage battery packages (maximum 1,200,000 JPY/unit), and for additional storage battery units, it is 60,000 JPY per kWh (maximum 720,000 JPY/unit), with additional amounts for participation in DR demonstrations.
The target is equipment registered with SII (Environmental Collaboration Initiative). If applying for pre-application after October 1, 2026, only equipment listed in the Reiwa 8 fiscal year SII registered product list will be eligible. This project is intended for simultaneous installation with solar power, but applications can be made for storage batteries alone. The application for grants and performance reports has been open since June 30, 2026.
👉 Cool Net Tokyo | Official page for storage batteries is here
Chofu City “Subsidy for Residential Energy Creation and Energy-Saving Equipment Installation”
In Chofu City, subsidies are available for those who install renewable energy and energy-saving equipment in residential homes within the city. For the fiscal year Reiwa 8, the subsidy amount is set at the lower of the actual expenditure for solar power generation or 20,000 yen per kW (up to 100,000 yen), and for storage batteries, the lower of the actual expenditure or a flat 50,000 yen. Eligible applicants are owners of individual residences and mixed-use buildings (including new constructions) within the city, and they must have fully paid any overdue city taxes. Solar power generation requires a contract with an electric company and certified equipment, while storage batteries must have a charging function from solar power generation.
Applications are accepted via post-installation application, and must be submitted within six months from the completion date of the installation (must arrive by this date). Applications will be accepted from April 1, 2026, to March 10, 2027 (must arrive by this date), but due to budget limitations, the application period may end before the deadline. Equipment that has not received subsidies from other city programs is eligible. Please check the city’s official page for the application status.
👉 Click here for Chofu City Official Page (Subsidy for Installation of Renewable Energy and Energy-Saving Equipment for Residential Use)
National Subsidy “DR Household Storage Battery Project (Support Project for the Introduction of Household Storage Systems for DR Resources)”
The national government has been implementing the “DR Household Storage Battery Project” to support the installation of household storage batteries.
This program is aimed at those who are newly introducing registered storage systems that can be used for demand response (DR), and in the fiscal year Reiwa 7 supplementary budget, the subsidy amount was determined based on a standard amount of 34,500 yen per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum of 600,000 yen per application. There are also conditions such as that contracts or orders made before the grant decision are not eligible.
However, the Reiwa 7 supplementary budget reached its budget limit on May 29, 2026, and the public offering has ended (the previous fiscal year Reiwa 6 supplementary budget also ended its public offering on July 2, 2025). Applications are currently not being accepted, so please check the official site for future public offerings.
Additionally, there are currently no subsidies available from the national government specifically for the installation of solar panels on existing homes.
👉 Click here for the Official Site of the DR Household Storage Battery Project
Price List for Solar Panel Installation and Storage Battery Installation
⇧Service Menu | For Costs Related to Solar Panel Removal and Water Heater Removal, Click Here
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and storage batteries should be confirmed by separating them into “Equipment Costs (Device Costs)” and “Construction Costs”.
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and Storage Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatt). Storage batteries are compared based on the amount of electricity they 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 roof’s shape, orientation, and size. At Kakeru Koumuten, we create layout diagrams from blueprints and on-site surveys to present the installation capacity.
On our pricing page, we list solar panel installation costs 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 estimated amounts and may vary based on wiring length, scaffolding area, existing roofing materials, panel layout, etc.)
▶ 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. Please check if the following items are clearly stated in each company’s estimate!
| 1. Solar Panels | Manufacturer, model number, output per 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 in conjunction with the battery. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range of use during power outages (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of the hardware suitable for the roofing material and method of securing it (whether it involves drilling holes or clamping). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, presence of a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at fixed points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | Extent of support for applications to the power company, certification 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 is tax-inclusive or tax-exclusive, conditions under which additional costs may arise, details and duration of manufacturer and workmanship warranties. |
If the capacities differ, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome comparisons, so if you bring estimates from other companies, we can explain the differences for each item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can obtain 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 Testimonials
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customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
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customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
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customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
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customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
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customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
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customer reviews
Higashiyamato City, Tokyo | We received reviews about exterior painting and roof overlay (cover method)!
Case Studies of Solar Panel Installations
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh class |
| Base Mounting Hardware Used |
| Niigata Manufactured / 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 Expected recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant amount and recovery estimates are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| About 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 will 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 grant amount, so we explained it to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Chofu City, Tokyo
There are many solar panel installation contractors available in Chofu City, Tokyo, and you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s check the following 4 points.
● Have extensive knowledge not only about solar energy but also about roofs
● Confirm the existence of warranties and aftercare services
● Obtain estimates from multiple contractors (3 companies as a guideline)
● Check if they provide support for subsidy applications
By confirming the above 4 points, you will be able to choose a reliable contractor.
Have knowledge not only about solar panels but also about roofs
Defective installation of solar panels can sometimes 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 were installed on a severely deteriorated roof, leading to leaks
・Solar panels were installed on a roof with a short lifespan, requiring a remodel to detach and reattach the solar panels within a few years
・Misjudged the type of waterproofing and performed incorrect treatment, 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 Verification 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, disclaimers, and cost conditions.
While the solar panels and battery storage units come with a manufacturer’s warranty, it is also important to check for the existence of a workmanship warranty in case leaks occur after installation!
For contractors that offer a workmanship warranty, if leaks occur after installation, they may 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.
Since abnormalities or damage on the roof can occur in areas that are not visible, there is a possibility that customers may not notice them themselves.
By conducting inspections in 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 unless roof renovations are performed.)
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 for 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, please check:
“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 judgments based solely on price!
▶ 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 subsidy may not be granted.
There are systems that require personal applications and cannot be applied for by the contractor, as well as systems that require prior application before installation, so it is reassuring to have a contractor who can support you in preparing necessary documents and understanding the application process.
Complete the procedures specified for each system (for Tokyo’s subsidy, prior application before installation; for Chofu City’s subsidy, application within 6 months after installation and confirmation of acceptance status) before proceeding with the construction!
In the case of subsidies in Tokyo, the process involves submitting a grant application and performance report after the completion of the work, which will be granted after a review. For subsidies in Chofu City, the application will be made after the completion of the work! (The procedure varies depending on the system.)
▶ Go to “Subsidies and Grants Available in Chofu City” within this article
Benefits of Introducing Solar Power Equipment
The benefits of introducing solar panels are summarized in the following five points!
Benefit 1: Economic Advantage
The biggest advantage of introducing solar panels is the economic benefit!
While the selling price of electricity has decreased compared to ten years ago, you can gain benefits by reducing the electricity purchased from the power company through self-consumption of the generated electricity!
As electricity prices rise, the ability to cover your consumption with solar power becomes increasingly attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
For residential (under 10kW) selling prices (FIT), the pricing from certifications after October 2025 will be set at “24 yen/kWh for the first four years, and 8.3 yen/kWh from the fifth to the tenth year.” The same pricing will apply for the 2026 fiscal year. After the fifth year, it is generally more advantageous to use it at home (self-consume) rather than sell it, making the combination with a storage battery a viable option.
👉 For purchase prices and periods, 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 Chofu City, you may be eligible for programs from the national government, Tokyo, and Chofu City.
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 like power conditioners may produce operational noise.)
Benefit 4: Expect Heat Insulation Effects!!
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 expected heat insulation effects!
(Note that this does not improve the insulation performance of the building itself.)
Benefit 5: Electricity can be used even during power outages!!
If a storage battery is installed, it becomes possible to use electricity even during emergencies like power outages!
Even without a storage battery, if you have a power conditioner with autonomous operation capabilities, 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 are incurred
A particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reattaching the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing the solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to consider maintenance costs in 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 where fasteners are fixed to the roofing material or substrate, waterproofing of the fixed parts 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, replacing the roofing material with a metal roof and fixing the solar panels using the catch method is also an option. (The catch method has compatibility conditions between the roofing material and the fasteners, and it cannot be used with all metal roofs.)
Catch-type base metal fittings for horizontal metal roofs
Note 3: The roof will become heavier
Since solar panels will be installed, the roof will become heavier. After investigating the existing roof, substrate, and load capacity, replacing with a 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 based on total roof output
When installing solar panels on the roof, it is important to know how much electricity can be generated in a limited area, and it is better to generate more electricity!
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 that 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 calculations are for total output (kW). The actual electricity generation amount (kWh) will vary depending on conditions such as roof orientation, slope, and shading.
How to Choose 2: Compare based on degradation rate of solar panels
Solar panels have a degradation rate, and their output gradually decreases after 10 years and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output guarantee value is a standard figure for warranty purposes and does not indicate the actual degradation rate or electricity generation itself.
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 based on warranty period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Regarding the output warranty, some manufacturers offer a 30-year warranty while others provide a 10-year warranty, so it varies!
It’s always better to have a longer warranty, so let’s check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Chofu City
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Chofu City. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Chofu City, Tokyo?
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 based on capacity are available on the 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 Chofu City?
As of October 7, 2026, the Tokyo Metropolitan Government is accepting pre-applications for subsidies for solar power generation and storage batteries (Cool Net Tokyo). For storage batteries, only SII registered devices (products registered in Reiwa 8) are eligible for pre-applications made after October 1, 2026. Chofu City’s “Subsidy for Residential Renewable Energy and Energy-Saving Equipment Installation” will be accepted from April 1, 2026, to March 10, 2027 (must arrive by this date), and due to budget constraints, it may end before the deadline. The national DR household storage battery project has already closed its public recruitment.
The acceptance status may change, so 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?
For many programs, procedures are required before construction. Tokyo’s subsidies require pre-application before installation, and if you install it first, you will be excluded from eligibility. Chofu City’s subsidy allows applications after installation is completed, but applications must be made within six months of the completion date, and due to budget constraints, it may end before the deadline. Procedures vary by program.
The order of procedures differs 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 when fixing brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten Co., Ltd. is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation. If deterioration is progressing, we can also propose methods such as roof overlay (cover method) or complete 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 within 10 to 20 years after installation, there will be additional costs for removing and reinstalling solar panels. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with durable roofing materials before installation.
Please consult us about the installation process after confirming the condition of the roof through a site survey!
Should I install a storage battery together with the solar panels?
If you want to use the 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, the Tokyo Metropolitan Government’s subsidy for storage batteries is designed for simultaneous installation with solar panels, but you can also apply for just the storage battery. You can compare “solar panels only” and “solar panels + storage battery” through a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing or shaded roofs?
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 Chofu City, the shading caused by surrounding buildings and trees 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 panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roofing work is done simultaneously or depending on the shape of the roof and installation capacity.
Please note that there will be additional time required for applications for subsidies and power companies, so please consult us early.
What is the current selling price (FIT)?
For residential use (less than 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, with the same price applied in the 2026 fiscal year.
The idea is to recover the initial costs quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-service maintenance 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 is difficult to check areas on the roof by yourself, so please feel free to consult us if you have any concerns.
Can you also renovate roofs that already have solar panels installed?
It is possible. Kakeru Koumuten Co., Ltd. can detach and reattach solar panels in-house, allowing us to perform roof overlay (cover method) or re-roofing after removing the panels, and we will handle everything consistently until reinstallation. The removed panels can be stored in our own warehouse.
For costs, please refer to the solar panel detachment and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Chofu City, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roof work, and exterior wall work in Chofu City, Tokyo.
We have received many requests from customers, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received positive feedback from many customers.
We continue to update our construction performance each year 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 (cover method) and re-roofing but also partial roof repairs, exterior painting, and exterior wall cover methods.
We are also happy to assist with 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 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 the customer’s position and propose the best 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 are confident, so we welcome competitive quotes!
Estimates are completely free, and if our company is found to be inferior to others, you are welcome to decline!
Characteristics of Chofu City, Tokyo, and Points for Solar Work
Chofu City, Tokyo, is located in the Tama region. The official page of Chofu City publishes hazard maps for floods (external water) from the Tamagawa, Nogawa, Sengawa, and Iruma rivers, as well as internal water.
Below are summarized points to consider regarding the residential environment of Chofu City and when installing solar panels and storage batteries. (Tap to open)
View the characteristics of Chofu City, Tokyo, and points for solar work
■ Confirm the installation locations of storage batteries and power conditioners in conjunction with the hazard map assumptions
In the Flood and Internal Water Hazard Map of Chofu City (Reiwa 5, March revision), the expected flooding from the Tamagawa, Asakawa, Oguragawa, as well as the Nogawa, Sengawa, Iruma, Tanizawa, and Marukogawa rivers is indicated, along with the expected internal flooding that occurs during heavy rains exceeding the drainage capacity of the sewer system. When deciding on the installation location for storage batteries and power conditioners, it is advisable to check the flooding expectations for your residence on the hazard map and consider the height and position of the installation for peace of mind.
■ Tokyo’s annual sunshine hours are approximately 1,927 hours
According to the Japan Meteorological Agency’s average values (1991-2020), Tokyo’s annual sunshine hours are about 1,927 hours.
The amount of electricity generated varies by season, so it is important to conduct an annual power generation simulation and choose the capacity of the storage battery to match the times of high electricity usage.
■ Check for shadows from surrounding buildings and trees
In areas where buildings or trees are close by, the way shadows fall varies for each house depending on the roof’s orientation and height. Since solar panels generate less electricity when shaded, Kakeru Koumuten creates layout diagrams based on the drawings and the actual site conditions, allowing you to confirm through power generation simulations. Additionally, in areas with nearby trees, branches and fallen leaves may accumulate around the panels and rain gutters, so please consult us about inspections and cleaning after installation.
■ City subsidies require post-application within a specified period; Tokyo requires pre-application
The subsidies from Chofu City are post-application, which means you must apply within six months (postmarked) after the installation is completed. There is a limited budget, and it may end before the deadline. On the other hand, the Tokyo Metropolitan Government’s subsidy (Cool Net Tokyo) requires pre-application before installation. It is important to check the procedures and periods for each system in advance, in conjunction with the timing of the construction.
■ In narrow front road areas, plan scaffolding and equipment delivery carefully
In areas with narrow front roads or where surrounding buildings are close together, careful planning for scaffolding and equipment delivery may be necessary. Kakeru Koumuten will respond to the site conditions with our own scaffolding team and scaffolding materials.
■ Check the roof condition according to the age of the building
For buildings that have been around for a number of years, it is important to check the condition of the roofing materials and substrate before installing solar panels. Depending on the roof’s condition, installing them simultaneously with roof renovations can help reduce future costs for removing and re-installing the solar panels.
Our company serves Kanagawa Prefecture and Tokyo, and we handle many exterior and solar construction projects in Chofu City, Tokyo.
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 Chofu City, Tokyo
Kakeru Koumuten accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Chofu City, Tokyo
Chofu City Kamikegawa / Chofu City Iruma-cho / Chofu City Kamishirahara / Chofu City Kamifutada-cho / Chofu City Kikunodai / Chofu City Kokuryo-cho / Chofu City Kojima-cho / Chofu City Sasu-cho / Chofu City Shibasaki / Chofu City Shimoishihara / Chofu City Shimofutada-cho / Chofu City Jindaiji Kitamachi / Chofu City Jindaiji Higashimachi / Chofu City Jindaiji Minamimachi / Chofu City Jindaiji Motomachi / Chofu City Sengawa-cho / Chofu City Somechi / Chofu City Tamagawa / Chofu City Chofu Kaoka / Chofu City Tobitakyu / Chofu City Nishitsutsuji-gaoka / Chofu City Nishimachi / Chofu City Nomizu / Chofu City Higashitsutsuji-gaoka / Chofu City Fujimicho / Chofu City Fuda / Chofu City Midorigaoka / Chofu City Yakumo-dai / Chofu City Wakabacho
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・Trust Kakeru Koumuten for exterior renovations in Chofu, Tokyo!
・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 comparative 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!
・Find out more about solar power generation estimates here!
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contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
