Leave Your Solar Panel Installation Work in Nerima, Tokyo to Kakeru Koumuten Co., Ltd.!
For solar panel and battery installation in
Nerima Ward, Tokyo,
trust Kakeru Koumuten!
Kakeru Koumuten is a specialized exterior renovation company headquartered in Aoba Ward, Yokohama City.
As a company strong in roofing work, we are entrusted withsolar panel and battery installation considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Nerima Ward”
“Costs for Solar Panel and Battery Installation”
“Subsidies Available for Solar System Installation in Nerima Ward”
We will also explain the above three points!
Installing solar panels carries risks such as“the occurrence of leaks” and other troubles.
To ensure a satisfactory solar panel installation, we recommend obtainingthree estimates!
Table of Contents (tap to open/close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Nerima, Tokyo
- Roof Inspection Before Installing Solar Panels
- Subsidies and Grants That May Be Applicable in Nerima
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installation Company in Nerima, 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 Nerima
- If You’re Looking for a Solar Panel Installation Company in Nerima, Contact Kakeru Koumuten
- Characteristics of Nerima, Tokyo and Key Points for Solar Installation
- Service Area in Nerima, Tokyo
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Nerima, Tokyo
The reasons why our company is entrusted with solar panel installation by customers in Nerima, Tokyo include
that Kakeru Koumuten serves Kanagawa and Tokyo as its service areas,
and our unique strengths in solar panel installation that cannot be imitated by other companies, which have received high praise from many customers.
so we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from as many companies as possible!
1. We Also Handle Exterior Renovations Beyond Solar Panel Installation!
Troubles such as leaks that occur during solar panel installation may be caused by insufficient checks on the roof and waterproofing at the installation site.
Even if you are knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside your expertise, so caution is necessary.
It is reassuring to have knowledge about the roof to avoid maintenance and troubles after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent troubles after solar panel installation!
2.Equipment Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. has organized the following warehouses and material storage areas to provide solar work and exterior renovations at low cost and high quality.
We have established five bases centered in Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Ownership of Scaffolding Materials
To ensure safety during work on the roof, we own the necessary scaffolding materials for temporary scaffolding based on construction conditions, allowing us to assemble scaffolding ourselves.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also cut costs related to scaffolding work.
We have scaffolding materials for approximately 50 single-family homes!
Even in the residential area of Nerima Ward, our own scaffolding team will plan the scaffolding according to the site.
Storage of materials in our large warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, we can purchase materials at a lower cost!
Additionally, we always have stock of roofing materials, so we can provide swift responses in emergencies!
Sorting and transporting waste materials in-house
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut down on waste disposal costs.
Exterior renovation dedicated showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on the roofing materials!
It is also possible to simulate the revenue and installation costs when introducing solar panels!
Since roofing and exterior wall work often accompany each other, we also have samples of roofing materials and models that explain the structure, allowing for detailed explanations!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is all work performed by our own team.
By maintaining a consistent system from inquiry to project completion, Kakeru Koumuten can provide high-quality roof remodeling at reduced costs.
Additionally, one representative will handle everything from the estimate to project completion.
Since the person in charge does not change, whether it’s the sales representative or the construction management representative, smooth communication is possible.
We can perform consistent in-house work from temporary scaffolding installation to exterior wall painting and roof remodeling!
4. Various Permits and Skilled Workers on Staff
We have obtained construction industry permits and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal workers and painting technicians on staff, and we are confident in our construction techniques.
We are capable of handling large-scale roofing projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty, our solar panel installation work comes with our own workmanship warranty (leakage warranty)!
(The workmanship warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovation is performed. The workmanship warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary based on the warranty details.)
Aftercare maintenance is available annually, and we send out notification DM every year.
If you have any questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
We are equipped to handle various roof troubles and situations.
Even if we cannot access the roof at high altitudes, we can respond using a drone!
During leakage investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of the solar panels decreases due to dirt, we can also provide cleaning with a specialized brush.
We will respond according to the customer’s wishes.
7. Human Resource Development
We create various roof models for skill improvement and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly conduct skill enhancement training so that each staff member can respond to various cases.
8. Creation of Clear Materials and Simulations
At Kakeru Koumuten Co., Ltd., we provide not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar installation guidebook” and a “financial simulation” that takes into account loan interest rates and electricity costs.
The financial simulation can project cumulative income and expenses over 20 to 30 years.
We compile easy-to-understand materials that include important points and disadvantages for customers who may not be familiar with solar installations!
We encourage you to obtain comparative estimates and review plans from other companies!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 to 30 years.
It is crucial to confirm before installation whether it is safe to place them directly on the current roof, as this is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten Co., Ltd., which specializes in roofing work, has summarized the items to check before installation.
| 1. Type of roofing material and age | The method of securing the panels varies depending on the roofing material, such as slate, tiles, metal roofs, or flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest a roof renovation first. |
| 2. Condition of the substrate and waterproof sheet | If the sheathing or roofing (waterproof sheet) beneath the roofing material is damaged, it can affect the fastening strength and waterproofing. We also check for signs of leaks. |
| 3. Roof orientation, slope, and shadows | 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 based on the plans and the site, and you can confirm this with the power generation simulation. |
| 4. Roof shape and installable area | The number of panels (installation capacity) that can be placed depends on the shape and size of the roof. The number of panels that can be installed varies based on their size, so we compare the total output of the roof. |
| 5. Fixing method and waterproofing details | We check whether the panels will be secured by drilling holes in the roofing material or by using brackets to grip the roofing material. The fixing method varies by technique, so please confirm the waterproofing treatment of the fixing parts during the estimate. |
| 6. Weight of the roof | The roof will become heavier due to the added panels. After investigating the existing roof, substrate, and load-bearing capacity, replacing with lighter roofing materials may be an option if necessary. |
| 7. Location of equipment installation and wiring | We confirm the installation locations for the power conditioner and storage batteries, as well as the wiring routes to the distribution board. The length of the wiring also affects costs. |
Fixing Methods and Checkpoints by Roofing Material
| Roof Material | Main Fixing Method | Pre-installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (e.g., fixing brackets to the roof material and substrate with screws) | Waterproof treatment of fixing parts, cracks or deterioration of slate, condition of the substrate. If deterioration is advanced, consider roof overlay (cover method) or replacement first. |
| Tile Roof | Fixed with brackets and methods suitable for the type of tile (even methods that do not drill holes in the tiles will fix to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the investigation results, there may be methods to replace with lighter roofing materials before installation. |
| Metal Roof (Horizontal and Vertical) | Fixed with catch-type brackets that grip the 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 re-installing solar panels. If the roof is deteriorating, renovating to a highly durable roofing material before installation may help reduce costs in the long run.
Kakeru Koumuten Co., Ltd. specializes in roofing work and can also handle the removal and re-installation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Nerima, Tokyo
Potential Subsidies and Grants in Nerima, Tokyo
When introducing solar panels or storage batteries in Nerima, Tokyo, there is a possibility of being eligible for programs from “the national government,” “Tokyo,” and “Nerima City.”
The following information is based on the official pages of each program as of October 7, 2026. The application status may change depending on the budget and recruitment period, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| System | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Tokyo Metropolitan Government “Reiwa 8 Year Household Solar Power Generation Promotion Project” (Cool Net Tokyo) | New installation of certified solar modules in residential properties or their premises within Tokyo, with a system capacity of less than 50kW. Pre-application before installation is required. | Existing homes: 150,000 JPY/kW for 3.75kW or less (maximum 450,000 JPY), 120,000 JPY/kW for over 3.75kW New homes: 120,000 JPY/kW for 3.6kW or less (maximum 360,000 JPY), 100,000 JPY/kW for over 3.6kW (Additional costs for mounting frames, waterproofing work, and renovation defect insurance, etc.) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 to March 30, 2029 |
| Tokyo Metropolitan Government “Reiwa 8 Year Household Storage Battery Promotion Project” (Cool Net Tokyo) | New installation of storage batteries in residential properties within Tokyo, and must be SII registered equipment. This project is intended for simultaneous installation with solar power, but applications can be made for storage batteries only. Pre-applications after October 1, 2026 will only be eligible for SII registered products for Reiwa 8. | Storage battery package: 100,000 JPY/kWh (maximum 1,200,000 JPY per household) Storage battery unit expansion: 60,000 JPY/kWh (maximum 720,000 JPY per household) (Additional incentives for participating in DR demonstrations, etc.) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 |
| Nerima Ward “Carbon Neutral Equipment Installation Subsidy” Reiwa 8 Year | Owners or residents of existing homes within the ward (the completion date of installation must be more than one year after the building’s construction date. New homes are not eligible). Individuals and sole proprietors are eligible. Requirements include having paid installation costs themselves and not being in arrears on resident taxes. Storage batteries are not included in the ward’s subsidized equipment. Applications are made after installation is completed, not before. | Solar power generation: 80,000 JPY (fixed amount) Storage batteries: Not eligible for ward subsidy |
Installation completion period: From April 1, 2026 to March 31, 2027 Application acceptance: From April 15, 2026 to March 31, 2027 (must arrive by this date) It is announced on the ward’s official page that application acceptance has been suspended as of September 15, 2026, due to reaching the budget amount. Please check the ward’s official page for the resumption date. |
| National “DR Household Storage Battery Project” (Reiwa 7 Year Supplement) | New installation of household 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 3/10; maximum 600,000 JPY per application) | The budget was reached on May 29, 2026, and the public recruitment has ended. (Currently, applications cannot be made.) |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Batteries are one of the eligible facilities, but they must be combined with essential work such as insulation renovations of windows (openings) and the building structure, and applications cannot be made with just the installation of batteries. Solar panels are not included as eligible facilities | Batteries: 96,000 JPY/unit | Ends as soon as the budget limit is reached. Please check the official website for the application status |
In Tokyo, a pre-application before installation is required for subsidies, and starting construction beforehand may result in ineligibility. In Nerima Ward, applications are made after installation is completed, but it is necessary to meet the requirements for eligible facilities, completion date, and required documents, and applying does not guarantee that the subsidy will be granted. The subsidies in Nerima Ward are processed in the order of arrival, and applications will close once the budget is reached (as of October 7, 2026, applications are currently suspended). The ward’s subsidies target solar power generation, and batteries are not eligible. It is indicated on the ward’s official page that combining with national and Tokyo subsidies is possible. Procedures differ by system, so please confirm before contracting and starting work.
Kakeru Koumuten Co., Ltd. will provide guidance on eligibility conditions for each system after confirming them.
Tokyo “Reiwa 8 Fiscal Year Household Solar Power Generation Promotion Project”
In Tokyo, subsidies are provided for those installing solar power generation systems in residential homes through Cool Net Tokyo. The target is systems using certified solar modules installed newly in residential homes or on their premises, with a capacity of less than 50 kW. A pre-application before installation is required.
For existing homes, the subsidy amount is 150,000 JPY/kW for 3.75 kW or less (maximum 450,000 JPY), and 120,000 JPY/kW for more than 3.75 kW. Additionally, there are extra items such as installation of mounting frames, waterproofing work, and renovation defect insurance. The pre-application period is from May 29, 2026, and the application for subsidy and performance report is from June 30, 2026, to March 30, 2029. For details on eligible equipment and conditions, as well as budget status, please check the official page.
👉 Cool Net Tokyo | Official page for solar power generation is here
Tokyo “Reiwa 8 Fiscal Year Household Battery Installation Promotion Project”
Tokyo is also providing subsidies for batteries installed newly in residential homes. The subsidy amount is 100,000 JPY per kWh for battery packages (maximum 1,200,000 JPY/unit), and 60,000 JPY per kWh for additional battery units (maximum 720,000 JPY/unit), with additional amounts for participation in DR demonstrations.
The target is equipment registered with SII (Environmental Collaboration Initiative). If applying for pre-application after October 1, 2026, only equipment listed in the Reiwa 8 fiscal year SII registered product list will be eligible. This project is intended for simultaneous installation with solar power, but applications can be made for batteries alone. The application for subsidy and performance report has been open since June 30, 2026.
👉 Cool Net Tokyo | Official page for batteries is here
Nerima Ward “Carbon Neutral Equipment Installation Subsidy”
In Nerima Ward, a “Carbon Neutral Equipment Installation Subsidy” is being implemented for those who install energy-saving and energy-generating equipment in existing homes within the ward. For the fiscal year Reiwa 8, the subsidy amount for solar power generation systems is set at 80,000 yen (fixed amount). Eligible applicants are owners or residents of existing homes within the ward (the installation completion date must be more than one year after the new construction), including individuals and sole proprietors. Requirements include having paid the installation costs themselves, not being in arrears on resident taxes, and not having received a subsidy decision from the ward for similar equipment in the most recent fiscal year. Storage batteries are not included as eligible equipment for the ward’s subsidy (eligible items include solar power generation, Enefarm, EcoCute, high-insulation windows and doors, and LED lighting).
Applications must be submitted after installation is completed, not before construction (the installation completion period is from April 1, 2026, to March 31, 2027, and applications will be accepted from April 15, 2026, to March 31, 2027, by mail). Applications will be processed in the order they are received, and will close once the budget is exhausted. The ward’s official page indicates that applications were stopped on September 15, 2026, as the budget amount was reached. It is noted that this can be combined with subsidies from the national government and Tokyo Metropolitan Government.
👉 Here is the Nerima Ward official page (Carbon Neutral Equipment Installation Subsidy)
National Subsidy “DR Home Storage Battery Project (Support Project for Home Storage System Introduction for DR Resource Implementation)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program targets those who are introducing new registered products for storage systems that can be utilized for demand response (DR), and for the fiscal year Reiwa 7 supplementary budget, the subsidy amount was determined based on a standard amount of 34,500 yen per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum of 600,000 yen per application. There are conditions such as being ineligible if a contract or order was made before the subsidy decision.
However, the Reiwa 7 supplementary budget reached its application amount on May 29, 2026, and the public offering has ended (the previous fiscal year’s Reiwa 6 supplementary budget also ended on July 2, 2025). Applications are currently not possible, so 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 from the national government.
👉 Here is the official site for the DR Home Storage Battery Project
Solar Panel Installation & Storage Battery Installation Price List
⇧Service Menu | For Costs Related to Solar Panel Installation 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 depending on the shape, orientation, and size of the roof. 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 approximate 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 Confirm in the Estimate (Cost Check)
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 confirm 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 hardware suitable for roofing materials and method of fixing (whether it is a method that drills holes or a method that clamps and secures). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, and whether there is a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at fixed points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | How much support is included for applications to the power company, certification applications for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If it is simultaneous with roof work or exterior painting, check that the same scope and quantity are not double counted. |
| 9. Removal and Disposal | Whether the removal of existing solar water heaters or old panels and disposal costs for waste materials are included. |
| 10. Tax Classification and Warranty | Whether 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 and Loss Simulator 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 and replacement.
Customer Feedback
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customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
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customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
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customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
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customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
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customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
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customer reviews
Higashiyamato City, Tokyo | We received reviews about exterior painting and roof overlay (cover method)!
Case Studies of Solar Panel Installations
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh class |
| Base Mounting Hardware Used |
| Niigata Manufactured / Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Arrangement |
| Fixed by gripping the horizontal metal roof with catch type hardware (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the grant being provided, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant amount and recovery estimate are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| Approximately 3 days |
| Completion Month |
| April 2025 |
| Inquiry Details |
| I am considering the installation of solar panels and storage batteries. I heard that grants are available, and I would like to know how much can be provided. |
Our Proposal
We visited to provide a quote 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 Nerima, Tokyo
There are many solar panel installation contractors available in Nerima Ward, Tokyo, and you may be unsure which one to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s check the following four points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the presence of warranties and aftercare maintenance
● Obtain estimates from multiple contractors (three companies as a guideline)
● Check if they also provide support for subsidy applications
By confirming the above four points, you will be able to choose a reliable contractor.
Knowledge about roofs as well as solar panels
Defective installation of solar panels can sometimes be caused by a lack of knowledge and verification regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient verification of roofs and waterproofing
・Solar panels were installed on a severely deteriorated roof, leading to leaks
・Solar panels were installed on a roof with a short lifespan, requiring renovations to detach and reattach the solar panels within a few years
・Misjudging 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 unforeseen troubles.
▶ Go to “Roof Verification Before Installing Solar Panels” in this article
Confirm the presence of warranties and aftercare maintenance
When choosing a solar installation contractor, make sure to check for warranties. It is important to confirm not only the duration of the warranty but also the coverage, exclusions, and cost conditions.
While the solar panels and battery storage units come with manufacturer warranties, also check for the presence of a workmanship warranty in case leaks occur after installation!
For contractors that offer workmanship warranties, if leaks occur after installation, they may be able to respond under the warranty, provided it is within the warranty period and conditions.
Additionally, some contractors offer after-sales service separate from warranties, so be sure to check if the contractor you are considering has after-sales service.
Changes or damage on the roof may occur in areas that are not visible, so you might not notice them yourself.
By conducting inspections during after-sales maintenance, you can easily detect any abnormalities early, preventing major repairs or failures!
Kakeru Koumuten Co., Ltd. provides a leak warranty as part of the workmanship warranty for solar panel installations. (The warranty for solar panel installation 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 after-sales maintenance and send out annual direct mail!
Please check the direct mail, and if you wish, we will visit you for after-sales maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, be sure to obtain estimates from multiple contractors.
Even for the same manufacturer and the same construction content, costs may vary, and warranties and after-sales services may differ.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request from your desired contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates,
“Check the items in the estimate”
“Type of solar panel”
“Warranties and after-sales services”
and make a detailed comparison to make your decision! If the rank of auxiliary materials is low or if steps are skipped, costs can be reduced, so avoid making decisions based solely on price!
▶ Go to “Breakdown of installation capacity, 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 if there are deficiencies in the documents, the subsidy may not be granted.
There are systems that require personal applications and cannot be applied for by the contractor, as well as systems that require prior application before installation, so it is reassuring to have a contractor who can support you in preparing necessary documents and understanding the application process.
Complete the procedures specified for each system (for Tokyo’s subsidies, prior application before installation) before proceeding with the construction! For the Nerima Ward subsidy, applications are made after installation is completed, not before construction!
In the case of subsidies in Tokyo, the process involves submitting a grant application and performance report after the completion of the work, which will then be reviewed before the grant is awarded! For the subsidy in Nerima Ward, applications are made after installation is completed, followed by a review before the grant is awarded! (The procedure may vary depending on the system.)
▶ Go to “Subsidies and Grants That May Be Applicable in Nerima Ward” within this article
Benefits of Introducing Solar Power Equipment
The benefits of installing solar panels are summarized in the following five points!
Benefit 1: Economic Advantage
The biggest advantage of installing solar panels is the economic benefit!
Although the selling price of electricity has decreased compared to ten years ago, you can benefit by reducing the amount of electricity purchased from the utility company by consuming the power generated!
As electricity prices rise, the ability to cover your consumption with solar power becomes increasingly attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
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 generally more advantageous to use the electricity at home (self-consumption) rather than selling it, making the combination with a storage battery a viable option.
👉 For details on purchase prices and periods, visit the Agency for Natural Resources and Energy
Benefit 2 You Can Utilize Subsidies!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the requirements, you may be able to utilize subsidies!
Reducing the actual burden through subsidies is a significant advantage!
In the case of Nerima Ward, in addition to the national and Tokyo metropolitan programs, there is a possibility of qualifying for the Nerima Ward Carbon Neutral Equipment Installation Subsidy (solar power generation has a fixed amount of 80,000 yen. Storage batteries are not eligible for the ward’s subsidy), which requires application after installation is completed and is on a first-come, first-served basis.
Benefit 3 Environmentally Friendly!
Solar power generation contributes to mitigating global warming by reducing carbon dioxide emissions and dependence on fossil fuels.
Since solar panels do not produce noise or exhaust gases during the power generation process, they are considered an environmentally friendly method of generating electricity. (Devices like power conditioners may produce operational noise.)
Advantage 4 Heat insulation effect is expected!!
By installing them on the roof or rooftop, the panels block direct sunlight from hitting the roof.
Especially in summer, it can help reduce the temperature rise of the roof, thus providing a heat insulation effect!
(Note that this does not improve the insulation performance of the building itself.)
Advantage 5 Electricity can be used even during power outages!!
If a storage battery is installed, it becomes 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 the 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 methods for securing slate roofs and tile roofs vary depending on the construction method, but when using screws and other fasteners to secure the roofing materials and substrate, waterproofing at the fastening points becomes 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, one option is to replace the roofing material with a metal roof and secure the solar panels using the catch method. (The catch method has compatibility conditions between the roofing material and the fasteners, and it cannot be used with all metal roofs.)
Catch-type base fasteners 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-bearing capacity, replacing with a lighter roof may also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary widely.
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 by Total Output of the Roof
When installing solar panels on the roof, it is important to know how much electricity can be generated in a limited area, and the more electricity generated, the better!
Solar panels come in various sizes depending on the manufacturer, and their outputs also differ.
For example, a 350W output panel and a 400W output panel may seem at first glance that the higher output panel is better.
However, if the size of the panels does not fit well with the roof, “20 panels of 350W can be installed, while only 15 panels of 400W can be installed,” which means the number of panels that can be installed may differ even 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 is a calculation of total output (kW). The actual electricity generation (kWh) will vary depending on conditions such as roof orientation, slope, and shading.
Choosing Method 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 benchmark for the warranty, and it does not indicate the actual degradation rate or power generation amount.
Choosing solar panels while considering both the initial output and the degradation rate will help you avoid regrets!
How to Choose 3: Compare by Warranty Period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Some manufacturers offer a 30-year warranty for output, while others provide a 10-year warranty, so it is quite varied!
A longer warranty is always better, so be sure to check the warranty period and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar and Storage Battery Installation in Nerima Ward
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Nerima Ward. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Nerima Ward, 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.
Guidelines by capacity are available on the solar panel installation 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 Nerima Ward?
As of October 7, 2026, Tokyo’s subsidies for solar power generation and storage batteries (Cool Net Tokyo) are accepting pre-applications. For storage batteries, only SII registered devices (registered products for Reiwa 8) are eligible from pre-applications made after October 1, 2026. The subsidy for carbon neutrality equipment installation in Nerima Ward (solar power generation is a fixed amount of 80,000 yen, storage batteries are not eligible) has stopped accepting applications as of September 15, 2026, as the budget amount has been reached, according to the official page of the ward. The national DR home storage battery project has ended its public recruitment.
Since the application status may change, please refer to the subsidy and grant section and consult with us before signing a contract.
Can I apply for subsidies after the construction is completed?
For many programs, procedures are required before construction. Tokyo’s subsidies require pre-application before installation, and if you install first, you will be ineligible. On the other hand, the subsidy in Nerima Ward is applied for after the installation is completed, not before construction. The procedures differ by program.
Since the order of procedures varies by program, please confirm before signing a contract and starting construction.
Can solar panels be installed on slate roofs? I’m worried about leaks.
It is possible to install on a slate roof, but it is necessary to check the condition of the roofing material and substrate beforehand. The method of securing it varies by construction method, and when securing 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 re-roofing 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 within 10 to 20 years after installation, the cost of removing and reinstalling solar panels will be incurred separately. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with highly durable roofing materials before installation.
Please consult us on how to proceed with the installation after checking the condition of the roof during the on-site survey!
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 advantageous to use it in your home rather than selling it.
Additionally, the Tokyo Metropolitan Government’s subsidy for storage batteries is designed for simultaneous installation with solar panels, but applications can also be made for storage batteries alone. You can compare “solar panels only” and “solar panels + storage battery” through a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing 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 Co., Ltd., we create a layout diagram from the drawings and on-site survey, and provide you with the installation capacity and power generation simulation.
Even in residential areas of Nerima Ward, the way shadows are cast by surrounding buildings varies from house to house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
In the above construction example (solar panel 4.3 kW + storage battery), it took about 3 days. The duration may vary depending on whether roofing work is done simultaneously and the shape and installation capacity of the roof.
Please note that there will be additional time required for subsidies and applications to the power company, so please consult us as soon as possible.
What is the current selling price (FIT)?
For residential use (less than 10 kW), from the certification after October 2025, the first four years will be 24 yen/kWh, and from the fifth to the tenth year will be 8.3 yen/kWh, with the same price applied 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 Co., Ltd. provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you take care of maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten Co., Ltd. sends out annual after-sales maintenance notices via direct mail and visits customers who wish for inspections. We can also clean solar panels using a special brush if the power generation decreases due to dirt.
The roof is a place that is difficult to check by yourself, so 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 Co., Ltd. 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 consistently. The removed panels can be stored in our own warehouse.
For costs, please refer to the solar panel detachment and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Nerima Ward, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including roof work and exterior wall work, in Nerima Ward, Tokyo, including solar panel installations.
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 positive feedback from many customers.
We continue to update our construction performance each year, and we will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and re-roofing but also partial roof repairs, exterior wall painting, and exterior wall overlay methods.
We are also happy to handle small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide emergency measures without setting up scaffolding, as long as safety can be ensured, so please consult us!
“I want to know about recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide the best solutions for your specific requests.
We will never propose unnecessary work that prioritizes profit!
We always stand in the customer’s position and propose the best construction plans!
We are confident that we will not be outdone in terms of cost, quality, and organization compared to other companies in exterior construction!
We welcome competitive estimates because we are confident!
Estimates are completely free, and if you find our company to be inferior to others, you are free to decline!
Characteristics of Nerima Ward, Tokyo and Points for Solar Work
Nerima Ward, Tokyo, is located in the northwest part of the 23 wards of Tokyo and is an area with extensive residential neighborhoods. The official page of Nerima Ward provides a flood and internal water damage hazard map, indicating that floods are a risk in the Shakujii River, Shirako River, and Ekoda River, while other areas are at risk of internal water flooding.
We have summarized the points to consider when installing solar panels and storage batteries in the residential environment of Nerima Ward below. (Tap to open)
See the features of Nerima Ward, Tokyo, and points for solar construction
■ Confirm the installation location of storage batteries and power conditioners in conjunction with the flood hazard map
The flood hazard map of Nerima Ward assumes a maximum hourly rainfall of 153mm and a total rainfall of 690mm, indicating that the areas within the red frame are at risk of flooding from the rivers (Shakujii River, Shirako River, Ekoda River), while areas outside the red frame are at risk of internal water flooding (a phenomenon where drainage cannot handle the water and flooding occurs). It is noted that there is no risk of storm surge in Nerima Ward. When deciding on the installation location for storage batteries and power conditioners, it is advisable to check the flooding assumptions for your location on the hazard map and consider the height and position of the installation for peace of mind.
■ Tokyo’s annual sunshine hours are approximately 1,927 hours
According to the Japan Meteorological Agency’s average values (1991–2020), Tokyo’s annual sunshine hours are about 1,927 hours.
Since power generation varies by season, it is important to conduct a year-round power generation simulation and select the capacity of the storage battery to match the times of high electricity usage.
■ Check the shadows of surrounding buildings in areas where houses are close together
In areas where houses are adjacent, the shadow cast by surrounding buildings varies for each house depending on the roof’s orientation and height. Since solar panels generate less power when shaded, Kakeru Koumuten Co., Ltd. creates layout diagrams from blueprints and the actual site conditions, allowing you to confirm through power generation simulations.
■ The ward’s subsidy targets solar installations for “existing homes.” Storage batteries are not included
The subsidies in Nerima Ward are aimed at installations in existing homes within the ward (where the installation completion date is more than one year after construction) and do not cover new homes. Additionally, storage batteries are not included in the ward’s subsidized equipment. If you are considering the introduction of storage batteries, please check the applicable systems, such as subsidies from Tokyo Metropolis.
■ In areas with narrow front roads, plan scaffolding and equipment delivery carefully
In areas with narrow front roads or where surrounding buildings are close together, careful planning for scaffolding and equipment delivery may be necessary. Kakeru Koumuten Co., Ltd. will respond to the site conditions with our own scaffolding team and scaffolding materials.
■ Check the roof condition according to the age of the building
For buildings that have aged, it is important to check the condition of the roofing materials and substrate before installing solar panels. Depending on the roof’s condition, installing them simultaneously with roof renovations can help reduce future costs for removing and reattaching solar panels.
■ Subsidy applications: Tokyo before construction, Nerima Ward after installation completion
In Tokyo, prior application to Cool Net Tokyo is required before installation. The Carbon Neutral Equipment Installation Subsidy in Nerima Ward can be applied for after installation is complete, and applications will close once the budget is reached on a first-come, first-served basis. It is important to check the procedures and periods for each system in advance, in conjunction with the timing of the construction.
Our company serves Kanagawa Prefecture and Tokyo, and we handle many exterior construction and solar projects in Nerima 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 Nerima Ward, Tokyo
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Nerima Ward, Tokyo
Asahigaoka, Nerima Ward / Asahimachi, Nerima Ward / Oizumigakuencho, Nerima Ward / Oizumicho, Nerima Ward / Kasugacho, Nerima Ward / Kamishakujii, Nerima Ward / Kamishakujii Minamimachi, Nerima Ward / Kitamachi, Nerima Ward / Mukaiyama, Nerima Ward / Kotakecho, Nerima Ward / Sakaemachi, Nerima Ward / Sakuradai, Nerima Ward / Shimoshakujii, Nerima Ward / Shakujidaidai, Nerima Ward / Shakujicho, Nerima Ward / Sekimachihigashi, Nerima Ward / Sekimachiminami, Nerima Ward / Sekimachikita, Nerima Ward / Takayanodai, Nerima Ward / Takamatsu, Nerima Ward / Tagara, Nerima Ward / Tachinonocho, Nerima Ward / Doshida, Nerima Ward / Toyotamaue, Nerima Ward / Toyotamachu, Nerima Ward / Toyotamaminami, Nerima Ward / Toyotamakita, Nerima Ward / Nakamura, Nerima Ward / Nakamura Minami, Nerima Ward / Nakamura Kita, Nerima Ward / Nishioizumi, Nerima Ward / Nishioizumicho, Nerima Ward / Nishiki, Nerima Ward / Nankai, Nerima Ward / Nerima, Nerima Ward / Hazawa, Nerima Ward / Hayamiya, Nerima Ward / Hikarigaoka, Nerima Ward / Hikawadai, Nerima Ward / Higashioizumi, Nerima Ward / Fujimidai, Nerima Ward / Heiwadai, Nerima Ward / Minamioizumi, Nerima Ward / Minamitanaka, Nerima Ward / Miharaidai, Nerima Ward / Tanihara, Nerima Ward
・For exterior wall painting in Nerima, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・For roof renovations in Nerima, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・For exterior renovations in Nerima, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd. construction achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. construction menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・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!
・Check here for solar power generation estimates!
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contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
