Leave Your Solar Panel Installation in Sumida, Tokyo to Kakeru Koumuten Co., Ltd.!
For
Solar Panel and Battery Installation in
Sumida 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 with solar panel and battery installation considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Sumida Ward”
“About the Costs of Solar Panel and Battery Installation”
“About Subsidies Applicable for Solar System Installation in Sumida 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 obtaining estimates from about three companies!
Table of Contents (Tap to Open/Close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Sumida, Tokyo
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Sumida
- Price List for Solar Panel and 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 Sumida, 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 Battery Installation in Sumida
- If You’re Looking for a Solar Panel Installation Company in Sumida, Contact Kakeru Koumuten
- Characteristics of Sumida, Tokyo and Key Points for Solar Installation
- Service Area in Sumida, Tokyo
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Sumida, Tokyo
Regarding why our company is entrusted with solar panel installation by customers in Sumida, Tokyo,
One reason is that “Kakeru Koumuten covers Kanagawa and Tokyo as its service areas.” Additionally,
“We have unique strengths in solar panel installation that cannot be imitated by other companies,” which has received positive feedback from many customers.
We would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We also handle exterior renovations beyond solar panel installation!
Troubles such as leaks caused by solar panel installation may be due to insufficient checks on the roof and waterproofing at the installation site.
Even if you are knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside your expertise, so caution is necessary.
It is reassuring to be knowledgeable about the roof to avoid maintenance and troubles after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent troubles after solar panel installation!
2.Equipment Specialized in Exterior Remodeling
Kakeru Koumuten Co., Ltd. has organized the following warehouses and material storage areas to provide solar work and exterior remodeling 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 on scaffolding work.
We have enough scaffolding materials for approximately 50 single-family homes!
Even in Sumida Ward, which has many residential areas, our own scaffolding team plans 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 canpurchase materials at a lower cost!
Additionally, we always have stock of roofing materials, enabling us torespond quickly in emergencies!
Sorting and transporting waste materials in-house
The installation of solar panels often involves roofing work, resulting in 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 provide samples of roofing materials and models that show the structure, allowing for detailed explanations!
3.Complete In-House Construction
One of Kakeru Koumuten’s major strengths is 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 remodeling.
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 construction management representative, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation to exterior wall painting and roof remodeling!
4. Various Permits and Skilled Workers
We have obtained permits for the construction industry and for the collection and transportation of industrial waste!
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 coverage and conditions vary based on the warranty details.)
Aftercare maintenance is available annually, and we send out notification DM every year.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roof troubles and situations.
Even if we cannot access the roof at high altitudes, we can respond using a drone!
During leakage investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of the solar panels decreases due to dirt, we can also provide cleaning with a specialized brush.
We will respond according to the customer’s wishes.
7. Human Resource Development
To improve skills, we create various roof models and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly conduct technical training so that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
At Kakeru Koumuten Co., Ltd., we provide not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar installation guidebook” and a “profit and loss simulation” that takes into account loan interest rates and electricity costs.
The profit and loss simulation can be created for projected cumulative profits and losses over 20 to 30 years.
Even customers who are not familiar with solar installations will find our materials easy to understand, including important points and disadvantages!
We encourage you to obtain comparative estimates and review plans from other companies!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 to 30 years.
It is crucial to confirm “whether it is okay to install them directly on the current roof” before installation, 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) under the roofing material is damaged, it will affect the fastening strength and waterproofing. We also check for signs of leaks. |
| 3. Direction, slope, and shadows of the roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, will affect power generation. We create a layout diagram from the drawings and the site, and you can confirm it with the power generation simulation. |
| 4. Shape of the roof and 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 by panel size, so we compare based on the total output of the roof. |
| 5. Fixing method and waterproofing details | We check whether the method involves drilling holes in the roofing material for fastening or using brackets to secure the roofing material. The fixing method varies by technique, so please confirm the waterproof treatment method for the fixing parts during the estimate. |
| 6. Weight of the roof | The roof will become heavier due to the panels. After investigating the existing roof, substrate, and load-bearing capacity, switching to 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 battery, as well as the wiring route 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 secure 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 reinstalling solar panels. If the roof is deteriorating, it may be more cost-effective in the long run to renovate to a highly durable roofing material before installation.
Kakeru Koumuten Co., Ltd. specializes in roofing work and can also handle the removal and reinstallation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Sumida, Tokyo
Possible Subsidies and Grants in Sumida, Tokyo
If you are introducing solar panels or storage batteries in Sumida, Tokyo, there may be systems available from “the national government,” “Tokyo,” and “Sumida City”.
The following information is based on the official pages of each system as of October 7, 2026. The application status may change depending on the budget and recruitment period, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Tokyo Metropolitan Government “Fiscal Year 2026 Home Solar Power Generation Promotion Project” (Cool Network Tokyo) | New installation of certified solar modules in residential properties or their premises in 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 “Fiscal Year 2026 Home Battery Storage Promotion Project” (Cool Network Tokyo) | New installation of battery storage in residential properties in Tokyo, with SII registered equipment. This project is intended for simultaneous installation with solar power, but applications can be made for battery storage only. Pre-applications after October 1, 2026 will only be eligible for SII registered products for fiscal year 2026. | Battery storage package: 100,000 JPY/kWh (maximum 1,200,000 JPY per household) Battery unit expansion: 60,000 JPY/kWh (maximum 720,000 JPY per household) (Additional incentives for participation in DR demonstrations, etc.) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 |
| Sumida Ward “Global Warming Prevention Equipment Installation Subsidy Program” Fiscal Year 2026 | Applicable to single-family homes, businesses, and condominium units within the ward. For solar power generation systems, a power supply contract with an electric company and modules certified by JET or similar, with a maximum output of less than 10kW, are required. Battery systems are limited to equipment eligible for SII (Environmental Collaboration Initiative) subsidies. Application must be made before construction starts. | Solar power generation: 50,000 JPY per kW (maximum 200,000 JPY, lower than construction costs) Battery systems: 10% of construction costs (maximum 50,000 JPY) |
Application period: From April 1, 2026 to February 26, 2027 Applications must be made at the counter between one month and seven business days before construction starts (no mail applications). Applications will close once the budget is reached. |
| National “DR Home Battery Storage Project” (Fiscal Year 2025 Supplement) | New installation of home 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 30% and maximum 600,000 JPY per application). | The budget was reached on May 29, 2026, and the public recruitment has ended (applications are currently not accepted). |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Battery storage is one of the eligible facilities, but it must be combined with essential works such as insulation renovation of windows (openings) and the structure; applications cannot be made for battery installation alone. Solar panels are not included as eligible facilities. | 蓄電池：96,000 JPY/戸 | Ends when the budget limit is reached. Please check the official website for the application status. |
In Tokyo, the subsidy requires a pre-application before installation, while the Sumida Ward grant system requires application before construction. If construction begins before applying, it may become ineligible, and applying does not guarantee approval. The Sumida Ward grant can be combined with national and Tokyo subsidies, but the grant amount will be calculated after deducting the subsidy amount. Since the procedures differ for each system, please confirm before contracting or starting construction.
Kakeru Koumuten will guide you on eligibility conditions for each system after confirming them.
Tokyo “Reiwa 8 Year Household Solar Power Generation Promotion Project”
Tokyo is providing subsidies for those installing solar power generation systems in residential homes through Cool Net Tokyo. The target is systems using certified solar cell modules installed newly in residential homes or their premises, with a capacity of less than 50kW. A pre-application before installation is required.
The subsidy amount for existing homes is 150,000 JPY/kW for 3.75kW or less (maximum 450,000 JPY), and 120,000 JPY/kW for more than 3.75kW. Additionally, there are supplementary 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 grants and performance reports is from June 30, 2026, to March 30, 2029. For details on eligible equipment and conditions, as well as budget status, please check the official page.
👉 Cool Net Tokyo | Official page for solar power generation is here
Tokyo “Reiwa 8 Year Household Storage Battery Promotion Project”
Tokyo is also providing subsidies for newly installed storage batteries in residential homes. The subsidy amount is 100,000 JPY per kWh for storage battery packages (maximum 1,200,000 JPY/戸), and 60,000 JPY per kWh for additional storage battery units (maximum 720,000 JPY/戸), 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 year SII registered product list will be eligible. This project is intended for simultaneous installation with solar power, but applications can be made for storage batteries alone. The application for grants and performance reports has been open since June 30, 2026.
👉 Cool Net Tokyo | Official page for storage batteries is here
Sumida Ward “Global Warming Prevention Equipment Installation Grant System”
Sumida Ward has implemented a grant system for those installing global warming prevention equipment in buildings within the ward. The targets include single-family homes, businesses, and condominium units, with grant amounts set at 50,000 JPY per kW for solar power generation systems (maximum 200,000 JPY), and 10% of construction costs for home storage systems (maximum 50,000 JPY). For solar power, the calculation is based on product costs and construction costs of 500,000 JPY or less per kW, with the lower amount between construction costs and product costs being the grant amount.
The solar power generation system requires a power supply contract with the electric company, certification from JET or similar for the modules, and a maximum output of less than 10kW. The storage system is subject to the equipment designated by the SII (Environmental Co-Creation Initiative) for subsidies. The application period is from April 1, 2026, to February 26, 2027, but applications will close once the budget amount is reached.It is necessary to apply at the Environmental Conservation Division’s window at least 1 month to 7 business days before the start of construction (mail applications are not accepted), and applications after the start of construction will not be accepted. It can be combined with national and Tokyo Metropolitan subsidies, but the subsidy amount will be calculated after deducting those amounts.
👉 Here is the official page of Sumida Ward (Subsidy System for Introducing Equipment to Prevent Global Warming)
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 who are newly introducing registered storage systems that can be utilized for demand response (DR), and for the fiscal year 2025 supplementary budget, the subsidy amount is determined based on a standard amount of 34,500 yen per initial effective capacity of 1kWh, with a subsidy rate of up to 30% and a maximum of 600,000 yen per application. There are also conditions such as that contracts or orders made before the grant decision are not eligible.
However, the supplementary budget for fiscal year 2025 reached the application amount on May 29, 2026, and the public offering has ended (the previous fiscal year’s supplementary budget also ended on July 2, 2025). Applications are currently not possible, so please check the official website for future public offerings.
Currently, there are no subsidies confirmed for the installation of solar panels on existing homes.
👉 Here is the official site for the DR Home Storage Battery Project
Solar Panel Installation & Storage Battery Installation Price List
⇧Service Menu | Click here for costs related to solar panel removal and hot water heater dismantling
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and storage batteries should be confirmed by separating them into “Equipment Costs (Equipment Price)” and “Construction Costs”.
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and Storage Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatts). Storage batteries are compared based on the amount of electricity they can store, represented in kWh (kilowatt-hours).
The amount of kW that can be placed on the roof varies for each house depending on the roof’s shape, orientation, and size. At Kakeru Koumuten, we create layout diagrams from blueprints and on-site surveys to present the installation capacity.
On our pricing page, we list solar panels as approximately 800,000 JPY to 1,200,000 JPY for 3-5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6-10 kW. (These are just approximate amounts and may vary based on wiring length, scaffolding range, existing roofing materials, and panel layout.)
▶ Service Menu | Click here for costs related to solar panel installation and storage battery installation
Items to Confirm in the Estimate (Cost Verification)
When comparing estimates from different companies, it is common to compare different capacities and equipment based solely on price. Please check if the following items are clearly stated in each company’s estimate!
| 1. Solar Panels | Manufacturer, model number, output per panel (W), number of panels, total installation capacity (kW) should be specified. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls the battery together. |
| 3. Storage Battery | Manufacturer, model number, capacity (kWh), range usable during a power outage (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Fittings | Name of fittings suitable for roofing materials and method of securing them (whether it involves drilling holes or using clamps). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, presence of a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at fixed points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | Extent of support for applications to the power company, feed-in tariff (FIT) certification applications, and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If roof work and exterior painting are done simultaneously, check that the same scope and quantity are not double-counted. |
| 9. Removal and Disposal | Whether the removal of existing solar thermal water heaters or old panels and disposal costs for waste materials are included. |
| 10. Tax Classification and Warranty | Whether prices are tax-inclusive or tax-exclusive, conditions under which additional costs may arise, details and duration of manufacturer warranties and workmanship warranties. |
If the capacities differ, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome competitive estimates, 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 obtain an estimated quote and a profit simulation for up to 30 years!
If you know the total solar panel installation capacity for the roof and the capacity of the storage battery, you can get an estimated quote and profit simulation!
*The simulation results are estimates. Actual profits may vary based on assumptions such as electricity rates, self-consumption ratios, feed-in prices, and costs for equipment inspection or 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)!
Examples of Solar Panel Installation
| 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 introduction 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 when solar panels are 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 Sumida, Tokyo
There are many solar panel installation contractors available in Sumida Ward, Tokyo, and you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s check the following four points.
● Ensure they have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and aftercare maintenance
● Obtain estimates from multiple contractors (three companies as a guideline)
● Check if they provide support for subsidy applications
By confirming the above four points, you will be able to choose a reliable contractor.
Knowledge about roofs as well as solar panels
Defective installation of solar panels can sometimes be caused by a lack of knowledge and 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 a renovation for removal and reinstallation 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 Check Before Installing Solar Panels” in this article
Confirm the existence of warranties and aftercare maintenance
When choosing a solar installation contractor, confirm the existence of warranties. It is important to check not only the duration of the warranty but also the coverage, exclusions, and cost conditions.
While the solar panels and battery storage units come with manufacturer warranties, also check for the existence of workmanship warranties in case leaks occur after installation!
For contractors that offer workmanship warranties, if leaks occur after installation, they may be able to address the issue under the warranty, provided it falls within the warranty period and conditions.
Additionally, some contractors offer after-sales service separate from warranties, so be sure to check if the contractor you are considering has after-sales service.
Changes or damage on the roof may occur in areas that are not visible, so there is a possibility that customers may not notice them.
By conducting inspections during after-sales maintenance, we can check the unseen areas and easily prevent major repairs or failures by detecting abnormalities early!
Kakeru Koumuten Co., Ltd. provides a leak warranty as part of the workmanship warranty for solar panel installations. (The warranty for solar panel installations is 10 years, and depending on the condition of the roof before installation, a roof renovation may be required to provide the warranty.)
We also conduct after-sales maintenance and send out DM every year!
Please check the DM, and if you wish, we will visit you for after-sales maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting the installation of solar panels, be sure to obtain estimates from multiple contractors.
Even for the same manufacturer and the same construction content, costs may vary, and warranties and after-sales services may differ.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request from your desired contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check the following:
“Check the items in the estimate”
“Type of solar panels”
“Warranties and after-sales services”
Make sure to compare these details carefully! If the rank of auxiliary materials is low or if processes are skipped, costs can be reduced, so avoid making judgments 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
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.
There are systems that require personal applications and cannot be handled by the contractor, as well as systems that require prior application before installation, so it is reassuring to have a contractor that supports the preparation of necessary documents and the flow of procedures.
Complete the procedures specified for each system (for Tokyo’s subsidy, prior application before installation; for Sumida Ward’s grant, application before construction) before proceeding with the work!
In the case of subsidies in Tokyo, the flow is that after the completion of the work, a grant application and performance report will be submitted, and it will be granted after examination! (The procedure varies depending on the system)
▶ To “Subsidies and Grants that May Be Applicable in Sumida Ward” within this article
Benefits of Introducing Solar Power Equipment
The benefits of introducing solar panels are the following 5 points!
Benefit 1: Economic Benefits
The biggest benefit of introducing solar panels is the economic benefit!
While the selling price of electricity has decreased compared to 10 years ago, you can gain benefits by reducing the electricity you buy from power companies by consuming the electricity you generate!
As electricity prices rise, the ability to cover your consumption with solar power becomes attractive!
If you want to use the generated electricity at night, the installation of a storage battery is essential!
Furthermore, the selling price (FIT) for residential use (under 10kW) is set at “24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year” for certifications after October 2025, and the same price will apply for the 2026 fiscal year. After the 5th year, it tends to be more advantageous to use it at home (self-consumption), so combining it with a storage battery is also an option.
👉 For purchase prices and periods, see 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 conditions, you may be able to utilize subsidies!
Reducing the actual burden amount through subsidies is a significant benefit!
In the case of Sumida Ward, in addition to national and Tokyo metropolitan systems, there is a possibility of being eligible for the Sumida Ward Global Warming Prevention Equipment Introduction Subsidy System (solar power generation systems and home storage systems) (application for the ward’s subsidy is required before construction starts).
Benefit 3: Environmentally Friendly!
Solar power generation has low carbon dioxide emissions and can reduce dependence on fossil fuels, contributing to the mitigation of global warming.
Since solar panels themselves do not emit noise or exhaust gases during the power generation process, they are considered an environmentally friendly method of power generation. (However, devices like power conditioners may have operational noise.)
Advantage 4 Expect Heat Shielding Effect!!
By installing the panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, it can help reduce the temperature rise of the roof, so a heat shielding effect is expected!
(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 is possible to use electricity even during emergencies such as power outages!
Even without a storage battery, if you have a power conditioner with autonomous operation capability, you may be able to use electricity from a dedicated outlet during daytime generation.
(Note that the devices, output, and duration that can be used during a power outage vary depending on the model and wiring method.)
What Points Should Be Noted When Introducing Solar Power Generation?
Next, we will explain the “3 Points to Note” when installing solar panels!
Point 1 Maintenance Costs are Incurred
A particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reinstalling the solar panels.
If the existing roof is deteriorated, it is reassuring to renovate it with durable roofing materials before installing the solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to consider maintenance costs in 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 by construction method, but when using screws or other fasteners to secure the roofing material 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, replacing the roofing material with a metal roof and securing the solar panels using the catch method is also an option. (The catch method has compatibility conditions between the roofing material and the fasteners, and it cannot be used with all metal roofs.)
Catch-type base fastener 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 it with a lighter roof may also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary 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 based on the 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 the more electricity generated, the better!
Solar panels come in various sizes and outputs depending on the manufacturer.
For example, a 350W output panel and a 400W output panel may seem that the higher output panel is better at first glance.
However, if the size of the panel does not fit well with the roof, “20 panels of 350W can be installed, while only 15 panels of 400W can be installed,” leading to different possible installation numbers 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 based on the degradation rate of solar panels
Solar panels have a degradation rate, and their output gradually decreases over 10 and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output warranty values are benchmark figures for guarantees and do not indicate the actual degradation rate or power generation amount.
Choosing solar panels while considering the degradation rate, not just the initial output, will lead to a decision without regrets!
How to Choose 3: Compare by Warranty Period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Some manufacturers offer a 30-year warranty for output, while others provide a 10-year warranty, so it varies widely!
Longer warranties are better, so be sure to check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Sumida Ward
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Sumida Ward. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Sumida 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 for different capacities are available on the solar panel installation and storage battery installation pricing page. We will create a layout diagram from the drawings and site survey and provide a free estimate!
Are there any subsidies available for solar power and storage battery installation in Sumida 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) from pre-applications after October 1, 2026, are eligible. Sumida Ward’s Global Warming Prevention Equipment Introduction Subsidy Program (50,000 yen per 1kW of solar power, maximum 200,000 yen; for storage systems, 10% of construction costs, maximum 50,000 yen) is accepting applications until February 26, 2027 (will end once the budget is reached). The national DR household storage battery project has closed its public recruitment.
Since the application status may change, please refer to the subsidy and grant section and consult us before signing a contract.
Can I apply for subsidies after the construction is completed?
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. Sumida Ward’s subsidy program also requires application before construction, and applications after construction are not accepted. Procedures differ by program.
Since the order of procedures varies by program, please confirm before signing a contract or 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 varies depending on the construction method, and in methods that secure hardware to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten Co., Ltd. is a specialized company in exterior renovations with a strong focus on 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 advanced.
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 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 to a highly durable roofing material before installation.
Please consult us about the installation process after checking the condition of the roof during the on-site survey!
Should I install a storage battery together with the solar panels?
If you want to use the generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price for electricity will be 8.3 yen/kWh after the fifth year, making it more advantageous to use it in your home rather than selling it.
Additionally, the Tokyo Metropolitan Government’s subsidy for storage batteries is designed for simultaneous installation with solar panels, but you can also apply for the subsidy for storage batteries alone. You can compare “solar panels only” and “solar panels + storage batteries” in a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing roofs or roofs with shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten Co., Ltd., 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.
Even in residential areas of Sumida Ward, the way shadows are cast by neighboring houses and surrounding buildings varies from one house to another. You can check the expected power generation through the power generation simulation.
How long will the construction take?
For the above construction example (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary depending on whether roofing work is done simultaneously or the shape and installation capacity of the roof.
Please note that there will be an additional period 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 (less than 10 kW), the selling price will be 24 yen/kWh for the first 4 years and 8.3 yen/kWh from the 5th to the 10th year for certifications after October 2025, and the same price will apply for the 2026 fiscal year.
The idea is to recover the initial costs quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten Co., Ltd. provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you provide maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten Co., Ltd. sends out annual after-service maintenance notices via direct mail, and we visit customers who wish to have inspections. We can also clean solar panels with a special brush if the power generation has decreased 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, all in one consistent process. The removed panels can be stored in our own warehouse.
For costs, please refer to the solar panel detachment and water heater removal pricing page.
If you are looking for a solar panel installation company in Sumida City, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including roof work and exterior wall work, in Sumida City, Tokyo, including solar panel installations.
We receive requests from many customers, including renovation companies and real estate companies, 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 records every year and will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and re-roofing but also partial roof repairs, exterior painting, and exterior wall overlay methods.
We are also happy to handle small jobs like partial repairs and rain gutter cleaning!
In urgent cases like leak repairs, we may be able to provide temporary 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 will propose the best construction plan!
We are confident that we will not be outdone in terms of cost, quality, and organization compared to other companies in 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 Sumida City, Tokyo and Points of Solar Work
Sumida Ward, Tokyo, is located in the eastern part of the 23 wards of Tokyo, where the Sumida River and Arakawa River flow. The official page of Sumida Ward indicates that in the event of flooding from the Arakawa River, a large part of the ward may be at risk of inundation, and flood hazard maps for flooding (Arakawa River flooding), storm surges, and rainwater discharge are available.
We have summarized the points to consider when installing solar panels and storage batteries in the residential environment of Sumida Ward below. (Tap to open)
View the characteristics of Sumida Ward, Tokyo, and points for solar installation
■ In areas at risk of flooding, confirm the installation locations of storage batteries and power conditioners in accordance with flood risk
The official page of Sumida Ward states that in the event of flooding from the Arakawa River, a large part of the ward may be at risk of inundation. The ward’s flood hazard map allows you to check the expected inundation from flooding (Arakawa River flooding), the duration of inundation, storm surges, and rainwater discharge. When deciding on the installation locations for storage batteries and power conditioners, it is advisable to check the flood risk for your residence on the hazard map and consider the height and position of the installation for peace of mind.
■ The annual sunshine hours in Tokyo are approximately 1,927 hours
The Japan Meteorological Agency’s average values (1991-2020) indicate that the annual sunshine hours in Tokyo are approximately 1,927 hours.
Since power generation varies by season, conducting a year-round power generation simulation and selecting the capacity of the storage battery to match the times of high electricity usage is essential.
■ In areas with closely situated houses, check for shadows from neighboring houses and buildings
In places where houses are closely built, the shadows cast by neighboring houses and surrounding buildings vary for each house depending on the roof’s orientation and height. Since solar panels generate less power when shaded, Kakeru Koumuten creates layout diagrams based on blueprints and the actual site conditions, allowing you to verify the power generation simulation.
■ In narrow residential streets, plan scaffolding and equipment delivery carefully
In residential areas with narrow front roads, careful planning for scaffolding and equipment delivery may be necessary. Kakeru Koumuten will respond according to the site with our own scaffolding team and scaffolding materials.
■ Check the roof condition according to the age of the building
For houses that have been built for several years, it is important to check the condition of the roofing materials and substrate before installing solar panels. Depending on the roof’s condition, installing them simultaneously with roof renovations can help reduce future costs for removing and reinstalling solar panels.
■ Subsidies require procedures before construction in both Tokyo and Sumida Ward
For subsidies in Tokyo, a pre-application to Cool Net Tokyo is necessary before installation. Sumida Ward’s subsidy program for introducing equipment to prevent global warming also requires application at the counter from one month to seven business days before construction begins. It is important to check the procedures and timelines for each program in advance, in conjunction with the timing of the construction.
Our company serves Kanagawa Prefecture and Tokyo, and we handle many exterior and solar construction projects in Sumida 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 Sumida Ward, Tokyo
Kakeru Koumuten Co., Ltd. accepts requests for work in Kanagawa Prefecture and all areas of Tokyo.
List of Areas in Sumida Ward, Tokyo
Azumabashi, Sumida Ward / Ishihara, Sumida Ward / Oshiage, Sumida Ward / Kamezawa, Sumida Ward / Kikukawa, Sumida Ward / Kyoshima, Sumida Ward / Kinshi, Sumida Ward / Koto-bashi, Sumida Ward / Sumida, Sumida Ward / Taihei, Sumida Ward / Tachibana, Sumida Ward / Tachikawa, Sumida Ward / Chitose, Sumida Ward / Tsutsumi-dori, Sumida Ward / Narihira, Sumida Ward / Higashi-Komagata, Sumida Ward / Higashi-Sumida, Sumida Ward / Higashi-Mukojima, Sumida Ward / Bunka, Sumida Ward / Honjo, Sumida Ward / Midori, Sumida Ward / Mukojima, Sumida Ward / Yahiro, Sumida Ward / Yokoami, Sumida Ward / Yokokawa, Sumida Ward / Ryogoku, Sumida Ward
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・Trust Kakeru Koumuten for exterior renovations in Sumida, Tokyo!
・Kakeru Koumuten Co., Ltd.施工実績
・Kakeru Koumuten Co., Ltd. After Maintenance
・Kakeru Koumuten Co., Ltd.施工メニュー・料金表
・Kakeru Koumuten Co., Ltd. Staff Blog & Announcements
・Explaining the Importance of Comparing Estimates!
・12 Major Manufacturers of Solar Power Generation! Features and Selection Points!
・What are the installation costs for solar power generation? Tips for Reducing Costs!
・What are the best locations for installing solar power generation? Points for Selecting Installation Locations!
・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!
