Leave Your Solar Panel Installation Work in Nakano, Tokyo to Kakeru Koumuten Co., Ltd.!
For solar panel and storage battery installation in
Nakano, Tokyo,
trust Kakeru Koumuten!
Kakeru Koumuten specializes in exterior renovations.
As a company strong in roofing work, we are entrusted withsolar panel and storage battery installations considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Nakano, Tokyo”
“Costs for Solar Panel and Storage 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 avoid regrets, we recommend obtainingthree estimates!
Table of Contents (Tap to Expand)
- Reasons Why 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
- Pricing Table 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 Consider When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions About Solar and Storage Battery Installation in Nakano, Tokyo
- If You Are Looking for a Solar Panel Installation Contractor in Nakano, Tokyo, Contact Kakeru Koumuten
- Characteristics of Nakano, Tokyo and Points for Solar Construction
- Service Area in Nakano, Tokyo
Reasons Why 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 Unique Strengths in Solar Panel Installation That Cannot Be Imitated by Other Companies”
have received high praise from many customers.
We would appreciate it if you could compare our estimates with those from other companies.
Because we are confident, we welcome multiple estimates!
1. We Also Handle Exterior Renovations Beyond 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 you are knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside your expertise, so caution is necessary.
It is reassuring to have expertise in roofing to avoid maintenance and issues after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent issues after solar panel installation!
2.Facilities Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. has prepared 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 for material storage and showrooms.
In-house Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding according to the construction conditions and can assemble the scaffolding ourselves.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also cut costs for scaffolding work.
We own scaffolding materials for approximately 50 single-family homes!
Even if there is a height difference 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 can purchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we can respond quickly in emergencies!
In-house sorting and transportation of waste materials
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 attached to the roofing materials!
We can also provide simulations for the potential earnings and installation costs when introducing solar panels!
Since roofing and exterior wall work often accompany renovations, we also have samples of roofing materials and models that explain the structure, allowing for detailed explanations!
3.All work performed by our own team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having Kakeru Koumuten handle everything from inquiries to project completion in a consistent manner, we can keep costs down while providing high-quality roof renovations.
Additionally, one representative will assist you from the estimate to the completion of the work.
Since the same person will handle sales and construction management, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation to exterior wall painting and roof renovations!
4. Various Permits Obtained & Skilled Workers on Staff
We have obtained permits for construction work and 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 roofing projects such as those for factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation work, our own construction warranty (leak warranty) is also included!
(The construction warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless a roof renovation is performed. The construction warranty is separate from the manufacturer’s product warranty, and the coverage and conditions vary based on the warranty details.)
Aftercare is available annually, 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.
Even if you cannot access the roof at high altitudes, we can utilize drones to assist!
During leak investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of solar panels decreases due to dirt or other factors, we can also provide cleaning services for solar panels using specialized brushes.
We will respond according to your wishes.
7. Human Resource Development
To improve skills, we create various roofing models and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly provide technical training to ensure that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
Kakeru Koumuten provides not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar construction guidebook” and “profit and loss simulations” that take into account loan interest rates and electricity costs.
Profit and loss simulations can be created for projected cumulative profits and losses over 20 to 30 years.
For customers who are not familiar with solar construction, we compile 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 safe to install 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 (rooftop waterproofing). If the remaining lifespan of the roofing material is short, we may suggest roof renovation first. |
| 2. Condition of Substrate and Waterproof Sheet | If the sheathing or roofing (waterproof sheet) under the roofing material is damaged, it will affect the fixing strength of the fittings and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, will affect the amount of electricity generated. We will create a layout diagram from the drawings and on-site, and you can check it with a power generation simulation. |
| 4. Shape of the Roof and Usable Area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. Since the number of panels that can be installed varies depending on the size of the panels, we will compare based on the 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 fixing or using fittings to secure the roofing material. The fixing method varies by technique, so please check the waterproofing treatment method for the fixing parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels. After investigating the existing roof, substrate, and load-bearing capacity, replacing with lighter roofing materials may be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will check the installation location of the power conditioner and storage battery, as well as the wiring route to the distribution board. The length of the wiring also affects the cost. |
| 8. Ease of Scaffolding Setup and Delivery Routes | If there are elevation differences on the site, planning for scaffolding and delivery routes for equipment and materials may require some ingenuity. The width of the front road and any steps on the site will also be checked during the on-site survey. |
Fixing Methods and Checkpoints by Roofing Material
| Roof Material | Main Fixing Method | Pre-Installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (e.g., fixing brackets to the roof material and substrate with screws) | Waterproofing treatment of fixing parts, cracks and deterioration of slate, condition of the substrate. If deterioration is significant, consider roof overlay or replacement first. |
| Tile Roof | Fixed with brackets and methods suitable for the type of tile (even methods that do not drill holes in the tiles will secure to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the survey results, there may be a method to replace with lightweight roofing material before installation. |
| Metal Roof (Horizontal and Vertical) | Fixed with catch-type brackets that grip the roof material (depends on the combination of roof material and brackets) | Whether the roof material and brackets are compatible, installation conditions from the roof material manufacturer. If compatible, 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 removing and reinstalling 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 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 Metropolitan Government,” 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 signing a contract or starting construction.
Eligibility Conditions and Application Timing for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Tokyo “Solar Power Generation Promotion Project for Households” | Individuals, corporations, or management associations installing unused solar power generation systems (output less than 50kW, JET certification, etc.) in residential properties within Tokyo. The generated power must be used in the residential part. Pre-application is required | Existing homes: 15,000 JPY per kW for 3.75kW or less (maximum 450,000 JPY), 12,000 JPY/kW for over 3.75kW up to less than 50kW New homes: 12,000 JPY/kW for 3.6kW or less (maximum 360,000 JPY), 10,000 JPY/kW for over 3.6kW |
For fiscal year 2026, pre-applications are being accepted from May 29 (will end once the budget is reached). From the pre-application for fiscal year 2026, submission of certificates issued by financial institutions during the performance report is mandatory |
| Tokyo “Battery Storage Promotion Project for Households” | Owners of eligible devices (battery storage registered with SII, excluding national and local governments). Installation must occur between April 1, 2026, and March 30, 2031. If pre-applying after October 1, 2026, only products registered with the national SII for fiscal year 2026 are eligible | Battery storage 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 equipment is installed) Expansion of battery storage unit: 60,000 JPY/kWh (maximum 720,000 JPY per household) |
For fiscal year 2026, pre-applications are being accepted from May 29. Grant application and performance report will start from June 30 |
| Nakano Ward “Energy Conservation Equipment Installation Subsidy” | Residents, management associations, local organizations, corporate businesses (small and medium enterprises), and sole proprietors. Equipment installed between February 1, 2026, and January 31, 2027, is eligible. Solar power must have an output of 2kW or more and not be for full sale, and the battery system must be 4kWh or more and connected to the solar power generation equipment. Application after installation completion (post-application) | Solar power generation system: 150,000 JPY Battery 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 Household Battery Storage Project” (Fiscal Year 2025 Supplement) | Newly introducing household battery 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 3/10, maximum 600,000 JPY per application) | The budget was reached on May 29, 2026, and the public offering has ended (there is no plan to reopen the public offering, and applications cannot be made at this time) |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Battery storage is one of the eligible facilities, but it must be combined with essential construction such as insulation renovation of windows (openings) and the building structure; applications cannot be made for just the installation of battery storage. Solar panels are not included as eligible facilities | Storage Battery: 96,000 JPY/unit | Ends as soon as the budget limit is reached. As of October 5, 2026, the application amount for renovations is displayed as 8% of the budget on the official site. Please check the application status on the official site. |
The Tokyo solar power and storage battery subsidies require 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 Ward 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 on November 30, 2026. Eligibility conditions, application procedures, and the possibility of combining with other systems differ for each program, and applying does not guarantee that subsidies will be granted, so please confirm before contracting and 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 Introducing Home Storage Systems for DR Resources)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program targets those introducing new registered storage systems that can be utilized 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 limit on May 29, 2026, and the public offering has ended. The official site also states that there are no plans to reopen the public offering, and applications cannot be made at this time. Please check the official site for future public offerings.
Additionally, there are currently no subsidies confirmed for the installation of solar panels on existing homes.
👉 Click here for the official site of the DR Home Storage Battery Project
Tokyo “Promotion Project for Introducing Solar Power Generation in Homes”
This subsidy is for those installing unused solar power generation systems in residential homes in Tokyo. The simultaneous installation of storage batteries is not a condition.
●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 structures and waterproofing work are also available.
The target is to install unused panels with a capacity of under 50 kW that have obtained JET certification, for use in residential areas in Tokyo. 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 a certificate issued by a financial institution during the performance report is now mandatory.
According to the official page of Tokyo, pre-registration is being accepted from May 29, Reiwa 8. It will end once the budget is reached, so please check the official page for the registration status.
👉 Here is the official page of Tokyo (Cool Net Tokyo)
Tokyo’s “Household 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)
●Expansion of battery unit: 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, Reiwa 8, and March 30, Reiwa 11. If pre-registration is done after October 1, Reiwa 8, only products registered with the national SII for Reiwa 8 will be eligible.
The official page of Tokyo states that pre-registration is being accepted from May 29, Reiwa 8. For detailed information, including conditions for combination with solar power generation, please check the official page.
👉 Here is the official page of Tokyo (Cool Net Tokyo)
Nakano Ward “Energy-Saving Equipment Installation Subsidy”
This subsidy is for those who install 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, and it is a post-application system that requires application after installation is completed. Applications can be submitted electronically or via paper application (Excel/PDF format) as well.
●Solar power system: 150,000 JPY (for systems with a total nominal output of 2 kW or more)
●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)
Eligible installations are those completed between February 1, Reiwa 8, and January 31, Reiwa 9. Solar panels must be new, certified by JET or similar, and not leased, with the condition that they are not intended for selling all generated electricity and must be owned and used for more than 5 years after installation. The battery system must also be new, not leased, and owned and used for more than 5 years after installation. The total budget is set at 91,450,000 JPY for both the first and second phases.
The official page of Nakano Ward (updated September 4, Reiwa 8) states that the first phase has reached its budget, so application acceptance has ended. The second phase is scheduled to accept applications from 8:30 AM on November 30, Reiwa 8, until February 28, Reiwa 9 (ending once the budget is reached). The registration status may change, so those considering applying should check the official page.
👉 Here is the official page of Nakano Ward
Solar Panel Installation & Battery Installation Price List
⇧Service Menu | For Costs Related to Solar Panel Installation & Battery Installation, Click Here
⇧Service Menu | For Costs Related to Solar Panel Removal & Water Heater Dismantling, 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.
Understanding Installation Capacity (kW) and Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatts). The battery is compared in terms of the amount of electricity it can store, 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 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 factors such as wiring length, scaffolding area, existing roofing materials, and panel layout.)
▶ Installation Menu | Costs for Solar Panel Installation and Battery Installation
Items to Check in the Estimate (Cost 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) should be listed. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls the battery together. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range usable during power outages (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of 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 at the fixing points, and whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | How much support is included for applications to the power company, certification application 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 and old panels, as well as 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, and details and duration of manufacturer and workmanship warranties. |
If the capacities differ, both the amounts 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 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 depending on assumptions such as electricity rates, self-consumption ratios, selling prices, and costs for equipment inspection and replacement.
Customer Feedback
-
customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
-
customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
-
customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
-
customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
-
customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
-
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-made Aluminum Catch-type Hardware |
| Fixing Method & Waterproofing Arrangement |
| Fixed by gripping the horizontal metal roof with catch-type hardware (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the grant being provided, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant amount and recovery estimate are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| 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 amount of the grant, 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 companies that cater to Nakano City, Tokyo, and you may be unsure which company to choose.
For this reason,when requesting solar panel installation or battery storage installation work, be sure to check the following four points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and aftercare services
● Obtain estimates from multiple companies (three companies is a guideline)
● Check if they provide support for subsidy applications
By confirming the above four points, you will be able to choose a reliable company.
Knowledge about roofs as well as solar panels
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 checks on 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, necessitating renovations to remove and reinstall the solar panels within a few years
・Misjudgment of the type of waterproofing led to incorrect treatment and subsequent 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 Checks Before Installing Solar Panels” in this article
Confirm the existence of warranties and aftercare services
When choosing a solar installation company, be sure to check for the existence of warranties. It is important to confirm not only the duration of the warranty but also the coverage, exclusions, and cost conditions.
While solar panels and battery storage come with manufacturer warranties, also check for the existence of installation warranties in case leaks occur after installation!
For companies that offer installation warranties, if leaks occur after installation, they may cover the repairs under the warranty, provided it is within the warranty period and conditions.
Additionally, some companies offer aftercare services separate from warranties, so be sure to check if the company you are considering has aftercare services.
Since abnormalities or damage on the roof may not be visible, you might not notice them yourself.
By conducting inspections of hidden areas during aftercare maintenance, you can more easily detect abnormalities early and prevent major repairs or failures!
At Kakeru Koumuten Co., Ltd., the installation of solar panels comes with a leak warranty as part of the workmanship warranty. (The warranty for solar panel installation is 10 years, and depending on the condition of the roof before installation, we may not be able to provide a warranty without performing roof renovations.)
We also conduct aftercare maintenance and send out annual DM!
After checking the DM, if you wish, we will visit you for aftercare maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting the installation of solar panels, 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 preferred contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check the following:
“Check the items in the estimate”
“Type of solar panel”
“Warranties and after-sales services”
Carefully compare these details to make your decision! 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
Confirm if they provide support for subsidy applications
There may be subsidies available for the installation of solar panels and storage batteries, but if the order of procedures is incorrect or if there are deficiencies in the documents, the subsidy may not be granted.
Since there are systems like the Tokyo subsidy that require prior application, it is reassuring to have a contractor who can support you in preparing necessary documents and understanding the procedure flow.
Make sure to complete the procedures required by 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 procedure flow varies by system)
▶ Go to “Subsidies and Grants that May Apply 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 generated electricity for your own use, 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 at “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 fiscal year 2026. After the fifth year, it is likely to be more advantageous to use it at home (self-consumption) rather than selling 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 Subsidies can be utilized!
Subsidy conditions and amounts vary by prefecture and municipality, but if you meet the conditions, you may be able to utilize subsidies!
The reduction of the actual burden amount through subsidies is a significant advantage!
In Nakano Ward, it is possible that the systems of the national government, Tokyo Metropolitan Government, and Nakano Ward may apply. The application for the previous term ended when the budget was reached, and the application for the latter term is scheduled to start from November 30, Reiwa 8 (2026) (please check the application status for each system).
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 power generation method (however, devices like power conditioners may have operational noise).
Advantage 4 Heat insulation effect is expected!!
By installing panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, this can help reduce the temperature rise of the roof, providing a heat insulation effect!
(Note that this does not improve the building’s insulation performance itself.)
Benefit 5: Electricity can be used even during power outages!!
If a storage battery is installed, it 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 functionality, 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 remodeling 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 remodel 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 in methods that fix hardware to the roofing material or substrate with screws, waterproofing of the fixed parts is crucial.
In methods that involve making holes in the roof, the risk of leaks inevitably arises.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, replacing the roofing material with a metal roof and fixing the solar panels using the catch method is also an option. (The catch method has compatibility conditions between the roofing material and hardware, and it cannot be used with all metal roofs.)
Catch-type base hardware for horizontal metal roofs
Point 3 Increased Weight of the Roof
Installing solar panels will add weight to the roof. After investigating the existing roof, substrate, and load-bearing capacity, replacing with a lighter roof may be one option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, each with varying outputs and costs.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
Choosing Method 1: Compare Based on Total Output of the Roof
When installing solar panels on the roof, it is important to consider how much electricity can be generated in a limited area, and generating more electricity is always better!
Solar panels come in various sizes and outputs depending on the manufacturer.
A 350W output panel and a 400W output panel may seem like the higher output panel is better at first glance.
However, if the size of the panel does not fit well on the roof, there may be cases where “20 panels of 350W can be installed” and “15 panels of 400W can be installed,” leading to different installation capacities on the same roof due to the size difference.
400W×15 panels = 6kW (total output of the roof)
350W×20 panels = 7kW (total output of the roof)
As shown above, even if the output of 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 calculations are for total output (kW). The actual electricity generation (kWh) will vary depending on conditions such as roof orientation, slope, and shading.
Choosing Method 2: Compare Based on Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases over 10 or 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 considering the degradation rate along with initial output, you can choose solar panels without regrets!
Choosing Method 3: Compare Based on Warranty Period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” with varying warranty periods depending on the manufacturer.
Some manufacturers offer a 30-year output warranty, while others may only provide a 10-year warranty, so it varies!
Longer warranties are generally better, so be sure to check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Installation 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 condition of the roof. In the above case study (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
Guidelines for different capacities are published on our solar panel and storage battery installation pricing page. We will create a layout diagram from the drawings and on-site survey and provide a free estimate!
Are there any subsidies available for solar and storage battery installation in Nakano, Tokyo?
As of October 7, 2026, Tokyo’s “Promotion Project for Solar Power Generation in Households” (for existing homes, 15,000 yen per kW for systems under 3.75kW, with a maximum of 450,000 yen) and “Promotion Project for Storage Battery Installation in 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 noted on the official Tokyo (Cool Net Tokyo) page. Nakano City has published that the subsidy for energy-saving equipment installation (150,000 yen for solar power systems and 100,000 yen for storage systems) ended for the first period when the budget was reached, and the second period is scheduled to start accepting applications from November 30, 2026, on Nakano City’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 with us before signing a contract.
Can I apply for subsidies after the construction is completed?
It varies by program. Tokyo’s subsidies require pre-application. Nakano City’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 differ by program, so please confirm before signing a contract.
The order of procedures varies by program, so please check before contracting and starting construction.
Can solar panels be installed on a slate roof? I’m worried about leaks.
Installation is possible on slate roofs, but it requires checking 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 crucial.
Kakeru Koumuten is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation and suggest methods such as roof overlay or replacement if deterioration is advanced.
The roof is old. Should I do a roof renovation first?
It depends on the condition of the roof. If a roof renovation is needed within 10 to 20 years after installation, the cost of removing and reattaching the solar panels will be incurred separately. If the remaining lifespan of the roof is short, renovating to a highly durable roofing material before installation may help reduce total costs.
After confirming the condition of the roof during the on-site survey, please consult us about the installation process!
Is it better to install a storage battery together with solar panels?
If you want to use the generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price for electricity will be 8.3 yen/kWh after the fifth year, making it more beneficial to use it in your home rather than selling it.
Additionally, the Tokyo Metropolitan Government’s subsidy for storage batteries (100,000 yen per kWh for the 2026 fiscal year, with a maximum of 1.2 million yen per household) aims to increase self-consumption of electricity generated by solar power. In Nakano City, storage systems (with a capacity of 4 kWh or more) connected to solar power generation equipment are also eligible for subsidies. You can compare “solar only” and “solar + storage battery” in a financial simulation for your consideration.
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 on-site survey, and we will provide you with the installation capacity and power generation simulation.
Nakano City is located on the Musashino Plateau, which has both plateau areas and lower lands in the Kanda River basin. The shape and orientation of the roof, as well as the shadows cast by surrounding buildings, vary from house to house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
In the above construction example (solar panel 4.3 kW + storage battery), it took about 3 days. The duration may vary if roof work is performed simultaneously or depending on the shape and installation capacity of the roof.
Please note that additional time is required for applications for subsidies and power companies, so please consult us as soon as possible.
What is the current selling price (FIT)?
For residential use (under 10 kW), the selling price from certifications after October 2025 will be 24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year, and the same price will apply for the 2026 fiscal year.
The idea is to recover initial costs more quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-service maintenance notices via direct mail and visits customers who request inspections. We can also clean solar panels with specialized brushes 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 handle renovations for roofs that already have solar panels installed?
Yes, we can. Kakeru Koumuten can detach and reattach solar panels in-house, allowing us to remove the panels, perform roof overlay (cover method) or re-roofing, and then reinstall them all in one go. The removed panels can be stored in our own warehouse.
For costs, please refer to the solar panel removal and hot 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, roofing work, and exterior wall work in Nakano, Tokyo.
We have received requests from many customers, including renovation companies and real estate agencies, who have contacted us!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received high praise from numerous customers.
We continue to update our construction performance records every year, and we will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and complete roof replacements but also partial roof repairs, exterior painting, and exterior cover installations.
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 about recommended solar panels”, “I want to keep costs as low as possible”, “I just want an estimate for now”, we will provide the best solutions for your specific requests.
We will never propose unnecessary work focused on profit!
We always stand in the customer’s position and propose the optimal construction plan!
We are confident that we will not be outdone by other companies in terms of cost, quality, and organization for exterior work!
We are confident, so we welcome competitive quotes!
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 for Solar Work
Nakano Ward has an area of 15.59 square kilometers and is 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 terrain and urban characteristics of Nakano, Tokyo, along with points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Nakano, Tokyo and points for solar work
■ 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 district’s green space survey, residential areas account for about 80% of the district, with the northern side along the JR Chuo Line designated as a Type 1 Low-Rise Residential Zone and the southern side as a Type 1 Medium-High-Rise Residential Zone. Even within the same district, the height of surrounding buildings varies by area, affecting the shadows cast on roofs. At Kakeru Koumuten Co., Ltd., we create layout diagrams from blueprints and on-site surveys, allowing you to check the expected power generation for each roof through our generation simulation.
■ Areas prone to dense building. Confirm scaffolding, delivery routes, and equipment placement
According to district 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 6th smallest among the 23 wards, and the building density is 40.0 buildings per hectare (the average for the 23 wards is 26.6 buildings), the highest in the 23 wards. In sites where the distance to neighboring houses is close, it is important to confirm the space for scaffolding, delivery routes for panels and batteries, and the placement of power conditioners and batteries in advance. Kakeru Koumuten Co., Ltd. plans scaffolding tailored to the site with our own scaffolding team.
■ Check flood and internal water hazard maps for the Kanda River and others. Be cautious about equipment installation locations
The Kanda River, Zenpukuji River, Myoshoji River, and Ekoda River flow through the district. The Nakano Ward hazard map displays external flooding from rivers and internal flooding from sewers and low-lying areas, based on the assumed maximum scale (153 mm in one hour, total rainfall of 690 mm), and also includes areas at risk of landslides. The impact of power conditioners and batteries, separate from the panels on the roof, may vary depending on where they are installed indoors or outdoors during flooding. Please check the flood assumptions for your residence on the district’s hazard map and consult with us about the installation location and height in conjunction with the manufacturer’s installation conditions.
■ Roof types and ages vary from house to house. Check the roof and waterproofing before installation
Even within the same district, the types of roofs, ages, and shapes of sites vary from house to house. At Kakeru Koumuten Co., Ltd., we will confirm the type and condition of the roof and the site situation before installation, and propose methods for securing and waterproofing, as well as scaffolding plans.
■ The annual sunshine hours at the Tokyo Observatory is about 1,927 hours
According to the Japan Meteorological Agency’s average values (1991-2020), the annual sunshine hours at the Tokyo Observatory is about 1,927 hours, with January (about 193 hours) having the most and June during the rainy season (about 124 hours) having the least. (This is a reference value, not based on measurements within Nakano Ward.)
The power generation in Nakano Ward can also be affected by shadows from surrounding buildings, so it is important to conduct annual power generation simulations and select battery capacities that align with peak electricity usage times.
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 replacements, and leak repairs, as well as other repairs! Please feel free to consult us about any sudden troubles!
Service Area in Nakano, Tokyo
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Nakano, Tokyo
Arai, Nakano / Ekoda, Nakano / Ebara-cho, Nakano / Kamisaginomiya, Nakano / Kamitakada, Nakano / Saginomiya, Nakano / Shiratori, Nakano / Chuo, Nakano / Nakano, Nakano / Numabukuro, Nakano / Nogata, Nakano / Higashi-Nakano, Nakano / Honcho, Nakano / Matsugaoka, Nakano / Maruyama, Nakano / Minamidai, Nakano / Yamato-cho, Nakano / Yayoi-cho, Nakano / Wakamiya, Nakano
・Trust Kakeru Koumuten for exterior wall painting in Nakano, Tokyo!
・Trust Kakeru Koumuten for roof renovations in Nakano, Tokyo!
・Trust Kakeru Koumuten for exterior renovations in Nakano, Tokyo!
・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 comparison estimates and key points!
・Top 12 solar power generation manufacturers! Features and selection tips included!
・What are the installation costs for solar power generation? Comprehensive tips to reduce costs!
・What are the best locations for solar power installation? Key points for site selection included!
・Find out more about solar power generation estimates here!
We welcome inquiries via LINE as well◎
We are also updating our Instagram regularly◎Please follow us◎
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!
