Leave Your Solar Panel Installation Work in Nakano, Tokyo to Kakeru Koumuten Co., Ltd.!
For Solar Panel and Battery Installation in Nakano, Tokyo,
Trust Kakeru Koumuten!
Kakeru Koumuten is a company specializing in exterior renovations.
As a strong player in roofing work, we are entrusted withsolar panel and battery installation considering roofs and waterproofing!
“How to Choose a Solar Panel Contractor in Nakano, Tokyo”
“Costs for Solar Panel and Battery Installation”
“Subsidies Available for Solar System Installation in Nakano, Tokyo”
We will also explain the above three points!
Installing solar panels carries risks such as“the occurrence of leaks” and other troubles.
To ensure you have no regrets about your solar panel installation, we recommend obtainingthree estimates!
Table of Contents (Tap to Open/Close)
- Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Nakano, Tokyo
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Nakano, Tokyo
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installation Contractor in Nakano, Tokyo
- Benefits of Introducing Solar Equipment
- Points to Note When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions About Solar and Storage Battery Installation in Nakano, Tokyo
- If You’re Looking for a Solar Panel Installation Contractor in Nakano, Tokyo, Contact Kakeru Koumuten
- Characteristics of Nakano, Tokyo and Key Points for Solar Installation
- Service Area in Nakano, Tokyo
Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Nakano, Tokyo
Regarding why our company is entrusted with solar panel installation by customers in Nakano, Tokyo,
“Our strengths in solar panel installation that cannot be imitated by other companies”
have received high praise from many customers.
so we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Also Handle Exterior Renovations Aside from Solar Panel Installation!
Issues 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 one is knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside their expertise, so caution is necessary.
It is reassuring to have expertise in roofing to avoid maintenance and trouble after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent issues after solar panel installation!
2.Facilities Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. has prepared the following warehouses and material storage areas to provide solar construction and exterior renovations at low cost and high quality.
We have established five bases for material storage and showrooms.
In-house Ownership of Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding based on construction conditions and can assemble scaffolding in-house.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also cut costs related to scaffolding work.
We own scaffolding materials for approximately 50 single-family homes!
Even if there are height differences on the site, our in-house scaffolding team will plan the scaffolding according to the local conditions.
Storage of Materials in Our Large Warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, you canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we canrespond quickly in emergencies!
Sorting and Transporting Waste Materials In-House
When installing solar panels, roofing work is often involved, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior Renovation Dedicated Showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on roofing materials!
Simulations for potential earnings and installation costs when introducing solar panels are also available!
Since roofing and exterior wall work are often involved, we also provide samples of roofing materials and models that explain the structure, allowing for detailed explanations!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having a consistent system from inquiry to project completion, Kakeru Koumuten can keep costs down while providing high-quality roof renovations.
Additionally, one representative will handle everything from the estimate to project completion.
Since the担当者 such as sales and construction management do not change, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation, exterior wall painting, to roof renovations!
4. Various Permits and Skilled Workers
We have obtained construction industry licenses and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal and painting technicians on staff, and we are confident in our construction techniques.
We can also handle large-scale roof projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation, we also provide our own施工保証 (leak warranty)!
(The施工保証 for solar panel installation is 10 years. Depending on the condition of the roof before installation, a roof renovation may be required to provide the warranty. The施工保証 is separate from the manufacturer’s product warranty, and the coverage and conditions vary depending on the warranty details.)
Aftercare is available every year, and we send out notification DM each year.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roofing troubles and situations.
If you cannot access the roof due to height, we can utilize drones for assistance!
During leak investigations, we can also conduct surveys 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 the customer’s wishes.
7. Human Resource Development
To improve skills, we create various roof models and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly conduct technical training to ensure that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
Kakeru Koumuten provides not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar panel installation guidebook” and a “profit and loss simulation” that takes loan interest rates and electricity costs into account.
The profit and loss simulation can be created for projected cumulative profits and losses over 20 to 30 years.
For customers who are not familiar with solar panel installations, we compile easy-to-understand materials that include points to consider and disadvantages!
We encourage you to obtain comparative estimates and compare them with other companies’ plans!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 to 30 years.
Confirming “Is it okay to install them directly on the current roof?” before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, which specializes in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Age | The fixing method varies depending on the roofing materials such as slate, tiles, metal roofs, and flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest roof renovation first. |
| 2. Condition of Substrate and Waterproof Sheet | If the underlayment or roofing (waterproof sheet) beneath the roofing material is damaged, it will affect the fastening strength and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, can affect power generation. We will create a layout diagram from the drawings and the site, and you can check it with a power generation simulation. |
| 4. Shape of the Roof and Installable 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 the panel size, so we will compare based on the total output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will confirm whether the method involves drilling holes in the roofing material for fastening or using brackets to secure the roofing material. The fixing method varies by technique, so please confirm the waterproof treatment method for the fixing parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels being installed. After investigating the existing roof, substrate, and load-bearing capacity, switching to lighter roofing materials may also be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will check the installation location of the power conditioner and storage battery, as well as the wiring route to the distribution board. The length of the wiring also affects the cost. |
| 8. Ease of Scaffolding Setup and Delivery Routes | If there are elevation differences on the site, careful planning for scaffolding and delivery routes for equipment and materials may be necessary. The width of the front road and any steps on the site will also be confirmed during the site survey. |
Fixing Methods and Confirmation Points by Roofing Material
| Roof Material | Main Fixing Method | Pre-Installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (such as 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 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 lightweight roofing materials before installation |
| Metal Roof (Horizontal and Vertical) | Fixed with catch-type brackets that grip the roof material (depends on the combination of roof material and brackets) | Whether the roof material and brackets are compatible, installation conditions from the roof material manufacturer. If compatible, methods that do not drill holes may be available |
| Flat Roof / Rooftop | Fixed by installing a framework | Type and deterioration status of the waterproof layer, waterproofing around the framework. Consider in conjunction with the timing of waterproofing work |
If you perform roof renovations 10 to 20 years after installation, there will be additional costs for removing and reinstalling solar panels. If the roof is deteriorating, it may be more cost-effective in the long run to renovate to a highly durable roofing material before installation.
Kakeru Koumuten is strong in roofing work and can also handle 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 Nakano, Tokyo
Possible Subsidies and Grants in Nakano, Tokyo
If you are introducing solar panels or storage batteries in Nakano, Tokyo, there is a possibility that the systems from “the national government,” “Tokyo,” and your local “Nakano Ward” may apply.
The following information is based on the official pages of each system as of October 7, 2026. The acceptance status may change depending on the budget, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Period for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Tokyo “Home Solar Power Generation Promotion Project” | Individuals, corporations, or management associations installing a new unused solar power system (output under 50kW, JET certification, etc.) in residential properties within Tokyo. The generated power must be used for residential purposes. Pre-application is required | Existing homes: 15,000 JPY per kW for up to 3.75kW (maximum 450,000 JPY), 12,000 JPY per kW for over 3.75kW and under 50kW New homes: 12,000 JPY per kW for up to 3.6kW (maximum 360,000 JPY), 10,000 JPY per kW for over 3.6kW |
For the 2026 fiscal year, pre-applications are being accepted from May 29 (will end once the budget is reached). From the pre-application for the 2026 fiscal year, submission of certificates issued by financial institutions will be mandatory at the time of performance reporting. |
| Tokyo “Home Storage Battery Promotion Project” | Owners of eligible devices (storage batteries registered with SII) excluding national and local governments. Installation must occur between April 1, 2026, and March 30, 2027. If applying after October 1, 2026, only products registered with the national SII for the 2026 fiscal year are eligible | Storage battery package: 100,000 JPY per kWh (maximum 1,200,000 JPY per household) Additional for participating in DR demonstration (100,000 JPY per unit; 150,000 JPY per unit if energy management devices are installed) Expansion of storage battery units: 60,000 JPY per kWh (maximum 720,000 JPY per household) |
For the 2026 fiscal year, pre-applications are being accepted from May 29. Grant applications and performance reports will be accepted from June 30. |
| Nakano Ward “Energy Conservation Equipment Installation Subsidy” | Residents, management associations, local organizations, corporate businesses (small and medium enterprises), and individual business owners. Equipment installed between February 1, 2026, and January 31, 2027, is eligible. Solar power systems must have an output of 2kW or more and not be for the purpose of full power sales; storage systems must be 4kWh or more and connected to solar power generation equipment. Applications must be submitted after installation (post-application) | Solar power generation system: 150,000 JPY Storage system: 100,000 JPY |
The first period reached the budget amount as of September 4, 2026, and applications are closed. The second period is scheduled from November 30, 2026, at 8:30 AM to February 28, 2027 (will end once the budget is reached). |
| National “DR Home Storage Battery Project” (2025 Fiscal Year Supplement) | Newly introducing home storage systems that can be utilized for DR (demand response) with registered products. | Calculated based on an initial effective capacity of 34,500 JPY per kWh (subsidy rate within 30% and maximum 600,000 JPY per application). | The budget was reached on May 29, 2026, and the public recruitment has ended (there are no plans to reopen public recruitment as stated on the official website, and applications are currently not accepted). |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Storage batteries are one of the eligible devices, but they must be combined with essential works such as insulation renovation of windows (openings) and structures; applications cannot be made for just the installation of storage batteries. Solar panels are not included as eligible devices | Storage battery: 96,000 JPY per household | As soon as the budget limit is reached, applications will close. As of October 5, 2026, the amount applied for renovations is displayed as 8% of the budget on the official website. Please check the official site for the application status. |
The Tokyo solar power and storage battery subsidy program requires prior application. For storage batteries applied for after October 1, 2026, only products registered with the national SII will be eligible, and the equipment requirements will change. The subsidy in Nakano City is a post-application system that requires installation to be completed before applying; the first application period has ended, and the second period is scheduled to start from November 30, 2026. Eligibility conditions, application procedures, and the possibility of combining different programs vary by system, and applying does not guarantee funding, so please confirm before contracting or starting work.
Kakeru Koumuten will provide guidance on eligibility conditions and application periods for each program after confirming them.
National Subsidy “DR Home Storage Battery Project (Support Project for the Introduction of Home Storage Systems for DR Resource Implementation)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program targets those who are newly introducing registered storage systems that can be used for demand response (DR), and in the fiscal year 2025 supplementary budget, the subsidy amount was determined based on a standard amount of 34,500 JPY per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum of 600,000 JPY per application. There are conditions such as that contracts or orders made before the grant decision are not eligible.
However, the fiscal year 2025 supplementary budget applications reached the budget on May 29, 2026, and the public recruitment has ended. The official site also states that there are no plans to reopen public recruitment, and applications are currently not possible. Please check the official site for future public recruitment.
Furthermore, there are currently no subsidies confirmed for the installation of solar panels on existing homes.
👉 Click here for the DR Home Storage Battery Project official site
Tokyo “Promotion Project for the Introduction of Solar Power Generation in Households”
This subsidy is for those who are newly installing unused solar power generation systems in residential homes in Tokyo. The simultaneous installation of storage batteries is not a requirement.
● Existing homes: For systems under 3.75 kW, 150,000 JPY per kW (maximum 450,000 JPY); for systems over 3.75 kW and under 50 kW, 120,000 JPY per kW
● New homes: For systems under 3.6 kW, 120,000 JPY per kW (maximum 360,000 JPY); for systems over 3.6 kW and under 50 kW, 100,000 JPY per kW
● Additional amounts for the installation of rooftop frames and waterproofing work are also available.
The target is for unused panels with an output of less than 50 kW that have obtained JET certification, installed in residential homes in Tokyo, and used in living areas. The process involves making a prior application and then applying for the grant after installation; starting from the fiscal year 2026 prior application, submission of certificates issued by financial institutions will be mandatory during the performance report.
The official page of Tokyo states that prior applications have been accepted since May 29, 2026. Applications will close as soon as the budget is reached, so please check the official page for the application status.
👉 Click here for the official Tokyo (Cool Net Tokyo) page
Tokyo “Home Battery Installation Promotion Project”
This is a subsidy for the installation costs of battery systems aimed at increasing self-consumption of electricity generated by solar power and improving energy independence during emergencies.
●Battery package: 100,000 JPY per kWh (up to 1,200,000 JPY per household)
●Additional for participating in DR demonstration: 100,000 JPY per unit (150,000 JPY per unit if energy management equipment is installed)
●Battery unit expansion: 60,000 JPY per kWh (up to 720,000 JPY per household)
Eligible applicants are owners of the subsidized equipment (excluding national and local governments), and installation must be completed between April 1, 2026, and March 30, 2027. If applying in advance after October 1, 2026, only products registered in the national SII for the fiscal year 2026 are eligible.
The official Tokyo page states that advance applications have been accepted since May 29, 2026. For detailed information, including conditions for combination with solar power generation, please check the official page.
👉 Official Tokyo (Cool Net Tokyo) page here
Nakano Ward “Energy-Saving Equipment Installation Subsidy”
This subsidy is for those installing energy-saving equipment such as solar power systems and battery systems in residential areas within the ward. Eligible applicants include residents, management associations, local organizations, corporate businesses (including small and medium-sized enterprises or other corporations), and individual business owners, with applications made after installation completion under a post-application system. Applications can be submitted electronically or via paper (Excel/PDF format) as well.
●Solar power system: 150,000 JPY (for systems with a total nominal output of 2 kW or more, etc.)
●Battery system: 100,000 JPY (for systems with a storage capacity of 4 kWh or more, connected to solar power equipment, and SII registered equipment, etc.)
Eligible installations must be completed between February 1, 2026, and January 31, 2027. Solar panels must be new, certified by JET or similar, and not leased, with the condition that they are not intended for full electricity sales and must be owned and used for more than five years after installation. Battery systems must also be new, not leased, and owned and used for more than five years after installation. The total budget is set at 91,450,000 JPY for both the first and second phases.
The official Nakano Ward page (updated September 4, 2026) states that the first phase has reached its budget limit, and application acceptance has ended. The second phase is scheduled to accept applications from November 30, 2026, at 8:30 AM until February 28, 2027 (ending as soon as the budget is reached). Since the application status may change, please check the official page if you are considering applying.
👉 Official Nakano Ward page here
Solar Panel Installation & Battery Installation Price List
⇧Service Menu | For Costs Related to Solar Panel and Battery Installation, Click Here
⇧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 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 Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatts). Batteries are compared based on the amount of electricity they can store, expressed in kWh (kilowatt-hours).
The amount of kW that can be placed on the roof varies for each house based 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 panels as approximately 800,000 JPY to 1,200,000 JPY for 3-5 kW and 1,200,000 JPY to 1,900,000 JPY for 6-10 kW. (These are just estimated amounts and may vary based on factors such as wiring length, scaffolding range, existing roofing materials, and panel layout.)
▶ Installation Menu | Costs for Solar Panel Installation and Battery Installation
Items to Check in the Estimate (Cost Confirmation)
When comparing estimates, it is common to compare different capacities and equipment. 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, and total installation capacity (kW) are specified. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls the battery together. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range usable during power outages (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of the hardware suitable for the roofing material and the fixing method (whether it is a method that drills holes or a method that clamps and fixes). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, and whether there is a monitor to check the power generation amount. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment for 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 applications for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If it is simultaneous with roof work or exterior painting, check that the same scope and quantity are not double-counted. |
| 9. Removal and Disposal | Whether the removal of existing solar thermal water heaters or old panels and disposal costs for waste materials are included. |
| 10. Tax Classification and Warranty | Whether it is tax-inclusive or tax-exclusive, conditions under which additional costs may arise, and details and duration of manufacturer and workmanship warranties. |
If the capacities differ, both the amount and power generation will change. Kakeru Koumuten Co., Ltd. welcome comparisons, so if you bring estimates from other companies, we will explain the differences for each item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can get an estimated quote and a financial 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 financial simulation!
*The simulation results are estimates. Actual financial results may vary based on assumptions such as electricity rates, self-consumption ratios, selling prices, and costs for equipment inspection or 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)!
Case Studies of Solar Panel Installations
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh |
| Base Mounting Hardware Used |
| Niigata Manufacturing/Aluminum Catch-Type Hardware |
| Fixing Method & Waterproofing Details |
| Fixed using catch-type hardware to grip 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 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 Nakano, Tokyo
There are many solar panel installation contractors available in Nakano, Tokyo, and you may be unsure which one to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s confirm the following 4 points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the presence of warranties and aftercare services
● Obtain estimates from multiple contractors (3 companies is 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
・Installed solar panels on a deteriorated roof, resulting in leaks
・Installed solar panels on a roof with a short lifespan, requiring remodeling for removal and reinstallation within a few years
・Misjudged the type of waterproofing and performed incorrect processing, leading to leaks
and more
When installing solar panels, understanding the condition and type of the existing roof allows you to avoid unnecessary expenses and unexpected troubles.
▶ Go to “Roof Verification Before Installing Solar Panels” in this article
Confirm the presence of warranties and aftercare services
When choosing a solar installation contractor, let’s confirm the presence of warranties. It is important to check not only the duration of the warranty but also the coverage, exclusions, and cost conditions.
Solar panels and battery storage units come with manufacturer warranties, but also check for the presence of installation warranties in case leaks occur after installation!
For contractors that offer installation warranties, if leaks occur after installation within the warranty period and conditions, they may cover it under the warranty.
Additionally, some contractors provide aftercare services separate from warranties, so make sure to check if the contractor you are considering has aftercare services.
Since abnormalities or damages on the roof may not be visible, you might not notice them yourself.
By conducting inspections of unseen areas during aftercare maintenance, you can more easily detect abnormalities early and prevent major repairs or failures!
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, a roof renovation may be required to provide the warranty.)
We also conduct aftercare maintenance and send out annual DM!
After confirming the DM, we will visit for aftercare maintenance if you wish!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, let’s obtain estimates from multiple contractors.
Even for the same manufacturer and the same 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 your desired contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check:
“Check the estimate items”
“Type of solar panels”
“Warranties and after-sales services”
and make a detailed comparison! Avoid judging solely based on cost, as using lower-grade materials or skipping processes can reduce costs!
▶ Go to “Breakdown of installation capacity, equipment, and 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 there are deficiencies in the documents, the grant may not be awarded.
Some systems, like the Tokyo subsidy, require prior application, so it is reassuring to have a contractor who supports the preparation of necessary documents and the flow of procedures.
Complete the procedures specified for each system (for the Tokyo subsidy, prior application) before proceeding with the construction!
For the Tokyo subsidy, after installation, you will need to submit a grant application and performance report, which will be reviewed before the grant is awarded! (The flow of procedures varies by system)
▶ Go to “Subsidies and grants that may be applicable in Nakano, Tokyo” in this article
Benefits of Introducing Solar Equipment
The benefits of introducing solar panels are as follows!
Benefit 1: Economic Benefits
The biggest advantage of introducing solar panels is the economic benefit!
The selling price of electricity has decreased compared to ten years ago, but by consuming the electricity generated, you can reduce the amount of electricity purchased from the utility company and gain benefits!
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!
Furthermore, the selling price (FIT) for residential use (under 10kW) will be set as “24 yen/kWh for the first four years, and 8.3 yen/kWh from the fifth to the tenth year” for certifications after October 2025, and the same price 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.
👉 Ministry of Economy, Trade and Industry | For purchase prices and periods, click here
Advantage 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 through subsidies is a significant advantage!
In Nakano Ward, there is a possibility of being eligible for the national, Tokyo, and Nakano Ward programs. The application for the first term in Nakano Ward ended when the budget was reached, and the second term is scheduled to start accepting applications from November 30, 2026 (please check the application status for each program).
Advantage 3 Environmentally friendly!
Solar power generation has low carbon dioxide emissions and can reduce dependence on fossil fuels, contributing to the mitigation of global warming.
Solar panels themselves do not produce noise or exhaust gases during the generation process, making them an environmentally friendly method of power generation. (However, devices like power conditioners may have operational noise.)
Advantage 4 Heat insulation effects are expected!!
By installing them on the roof or rooftop, the panels block direct sunlight from hitting the roof.
Especially in summer, this can help reduce the temperature of the roof, providing a heat insulation effect!
（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 is possible to use electricity even during emergencies such as power outages!
Even without a storage battery, if you have a power conditioner with autonomous operation capability, you may be able to use electricity from a dedicated outlet during daytime generation.
（The devices, output, and duration that can be used during a power outage vary depending on the model and wiring method）
What points should be noted when introducing solar power generation?
Next, we will explain the “three points to note” when installing solar panels!
Point 1: Maintenance costs can be incurred
A particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reattaching the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to consider maintenance costs in simulations before introducing solar panels!
Point 2: The risk of leaks increases depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but when fixing brackets with screws to the roofing material or substrate, waterproofing of the fixed parts becomes crucial.
If the method involves making holes in the roof, the risk of leaks inevitably arises.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, 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 the 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 also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
How to Choose 1: Compare by Total Output of the Roof
When installing solar panels on the roof, it is important to know how much power can be generated in a limited area, and the more power generated, the better!
Solar panels come in various sizes and outputs depending on the manufacturer.
For a panel with an output of 350W and a panel with an output of 400W, at first glance, the panel with the higher output may seem 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 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 a single panel is lower, the total output of the roof may be higher!
It is important to consider the total output of the roof rather than the output of a single panel!
*The above is a calculation of total output (kW). The actual power generation (kWh) will vary depending on conditions such as the roof’s orientation, slope, and shading.
How to Choose 2: Compare by Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases over 10 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 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 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.
For output warranties, some manufacturers offer a 30-year warranty, while others provide a 10-year warranty, so it varies widely!
Since longer warranties are 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 Nakano, Tokyo
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Nakano, Tokyo. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Nakano, Tokyo?
The cost varies depending on the installation capacity, equipment, and roof condition. In the above construction example (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
For cost estimates by capacity, please refer to the solar panel and storage battery installation pricing page. We will create a layout diagram from the drawings and site survey and provide a free estimate!
Are there any subsidies available for solar power and storage battery installation in Nakano, Tokyo?
As of October 7, 2026, Tokyo’s “Solar Power Generation Introduction Promotion Project for Households” (for existing homes, 15万円 per kW for systems under 3.75kW, with a maximum of 450,000 yen) and “Storage Battery Introduction Promotion Project for Households” (100,000 yen per kWh for storage batteries, with a maximum of 1.2 million yen per household) are accepting pre-applications starting May 29, 2026, as posted on the official Tokyo (Cool Net Tokyo) page. Nakano Ward’s energy-saving equipment installation subsidy (150,000 yen for solar power systems, 100,000 yen for storage systems) has closed for the first round due to reaching the budget limit, and the second round is scheduled to start accepting applications on November 30, 2026, as stated on Nakano Ward’s official page. 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 us before signing a contract.
Can I apply for subsidies after the construction is completed?
This depends on the system. Tokyo’s subsidies require pre-application. Nakano Ward’s grant is a post-application system, where installations completed between February 1, 2026, and January 31, 2027, are eligible. Conditions such as whether you can contract and start construction before applying vary by system, so please confirm before signing a contract.
The order of procedures varies by system, so please check before contracting and 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 confirmation of the roofing material and substrate condition is a prerequisite. 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 and suggest methods such as roof overlay (cover method) or complete replacement if deterioration is progressing.
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, 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 to high-durability 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 in your home rather than selling it.
Additionally, the subsidy for storage batteries in Tokyo (for Reiwa 8, it is 100,000 yen per kWh, with a maximum of 1.2 million yen per household) is aimed at increasing self-consumption of electricity generated by solar power. In Nakano Ward, storage systems (with a capacity of 4 kWh or more) connected to solar power generation equipment are also eligible for assistance. You can compare “solar only” and “solar + storage battery” in a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing roofs or roofs with shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten, we create a layout diagram from the drawings and site survey, and provide you with the installation capacity and power generation simulation.
Nakano Ward is located on the Musashino Plateau, which has both plateau surfaces and lower lands in the Kanda River basin, and the shape, orientation of the roof, and shading from surrounding buildings vary for each house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
For the above construction example (solar panel 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 as soon as possible.
What is the current selling price (FIT) for electricity?
For residential use (under 10 kW), the selling price will be 24 yen/kWh for the first four years and 8.3 yen/kWh from the fifth to the tenth year for certifications after October 2025, and the same price will apply in the 2026 fiscal year.
The idea is to recover initial costs more quickly in the first four years and then focus on self-consumption. Kakeru Koumuten provides a financial simulation considering loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-maintenance notices via DM and visits customers who wish to have 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 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 company in Nakano, Tokyo, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roof work, and exterior wall work in Nakano, Tokyo.
We receive requests from many customers, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low cost”, and we have received positive feedback from many customers.
We continue to update our construction achievements every year and will strive to improve quality to satisfy even more customers in the future.
Our company can perform not only roof overlay (cover method) and re-roofing but also partial roof repairs, exterior painting, and exterior wall cover methods all in-house.
We are also happy to assist with small jobs like partial repairs and rain gutter cleaning!
In urgent cases like leak repairs, we may be able to provide emergency measures without setting up scaffolding, as long as safety can be ensured, so please consult with us!
“I want to know 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 will propose the best construction plan!
We are confident that we will not lose in terms of cost, quality, and organization compared to other companies in exterior construction!
We welcome competitive quotes because we are confident!
Estimates are completely free, and if our company is found to be inferior to others, you are free to decline!
Characteristics of Nakano, Tokyo and Points of Solar Work
Nakano Ward has an area of 15.59 square kilometers, bordered by Shinjuku Ward and Toshima Ward to the east, Suginami Ward to the west, Shibuya Ward to the south, and Nerima Ward to the north. Within the ward, there are five plateaus: Numabukuro, Nogata, Nakano, Hatagaya, and Ochiai, with an elevation of about 40 meters on the plateau surface and below 30 meters in the Kanda River basin. We have summarized the characteristics of Nakano Ward, Tokyo, and points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Nakano Ward, Tokyo, and points for solar installation
■ A mix of plateaus and lowlands in the Kanda River basin. Residential areas are widespread, and shadows change with the height of surrounding buildings
According to the ward’s green reality survey, residential use areas account for about 80% of the ward, with the northern side designated as a Type 1 Low-Rise Residential Zone and the southern side as a Type 1 Mid-High Rise Residential Zone along the JR Chuo Line. Even within the same ward, the height of surrounding buildings varies by area, affecting the shadows cast on roofs. At Kakeru Koumuten, we create layout diagrams from blueprints and on-site surveys, allowing you to check the expected power generation for each roof through simulation.
■ An area prone to dense building. Confirm scaffolding, delivery routes, and equipment placement
According to the ward’s housing materials, the average site area of buildings is 179.5 square meters (the average for the 23 wards is 219.5 square meters), making it the sixth smallest among the 23 wards, with a building density of 40.0 buildings per hectare (the average for the 23 wards is 26.6 buildings), the highest among the 23 wards. In sites where the distance to neighboring houses is close, it is essential to confirm the space for scaffolding, delivery routes for panels and storage batteries, and the placement of power conditioners and storage batteries in advance. Kakeru Koumuten plans scaffolding tailored to the site with our own scaffolding team.
■ Check flood and internal water hazard maps for the Kanda River and others. Pay attention to equipment installation locations
The Kanda River, Zenpukuji River, Myoshoji River, and Ekoda River flow through the ward. Nakano Ward’s hazard map displays the expected maximum scale (153 millimeters in one hour, total rainfall of 690 millimeters), showing external flooding from overflowing rivers and internal flooding in sewers and low-lying areas, along with landslide hazard areas. Depending on where you install power conditioners and storage batteries, separate from the panels on the roof, the impact during flooding may vary. Please check the flooding assumptions for your location on the ward’s hazard map and consult with us regarding installation locations and heights in accordance with the manufacturer’s installation conditions.
■ The types and ages of roofs vary from house to house. Check the roof and waterproofing before installation
Even within the same district, the types of roofs, the age of the buildings, and the shape of the land vary from house to house. At Kakeru Koumuten Co., Ltd., we will check the type and condition of the roof and the situation of the land before installation, and propose methods for securing, waterproofing, and scaffolding plans.
■ The annual sunshine hours at the Tokyo Observatory is approximately 1,927 hours
According to the Japan Meteorological Agency’s average values (1991-2020), the annual sunshine hours at the Tokyo Observatory is approximately 1,927 hours, with January (approximately 193 hours) having the most, and June during the rainy season (approximately 124 hours) having the least. (This is a reference value, not based on observations in Nakano Ward.)
The power generation in Nakano Ward can also change due to shadows from surrounding buildings, so conducting a year-round power generation simulation and selecting the capacity of the storage battery to match the times of high electricity usage are key points.
Our company handles many exterior construction and solar projects in Nakano Ward, 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 for any sudden troubles!
Service Area in Nakano Ward, Tokyo
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Nakano Ward, Tokyo
Shinrai, Nakano Ward / Ekoda, Nakano Ward / Ebara-cho, Nakano Ward / Kamisaginomiya, Nakano Ward / Kamitakada, Nakano Ward / Saginomiya, Nakano Ward / Shirasagi, Nakano Ward / Chuo, Nakano Ward / Nakano, Nakano Ward / Numabukuro, Nakano Ward / Nogata, Nakano Ward / Higashi-Nakano, Nakano Ward / Honcho, Nakano Ward / Matsugaoka, Nakano Ward / Maruyama, Nakano Ward / Minami-dai, Nakano Ward / Yamato-cho, Nakano Ward / Yayoicho, Nakano Ward / Wakamiya, Nakano Ward
・For exterior wall painting in Nakano, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・For roof renovations in Nakano, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・For exterior renovations in Nakano, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd. project achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. service menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・Explaining the importance of comparative estimates and key points!
・Top 12 solar power manufacturers! Features and selection tips included!
・What are the installation costs for solar power? Comprehensive tips to reduce expenses!
・What are the best locations for solar power installation? Key points for site selection included!
・Check out our solar power estimate 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!
