Leave Your Solar Panel Installation Work in Minato, Tokyo to Kakeru Koumuten Co., Ltd.!
For solar panel and storage battery installation in
Minato, Tokyo,
trust Kakeru Koumuten Co., Ltd.!
Kakeru Koumuten Co., Ltd. specializes in exterior renovations.
As a company strong in roofing work, we are entrusted withsolar panel and storage battery installation considering roofs and waterproofing!
“How to Choose a Solar Panel Contractor in Minato, Tokyo”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Minato, Tokyo”
We will also explain the above three points!
Installing solar panels carries risks such as“the occurrence of leaks” and other troubles.
To ensure a satisfactory solar panel installation, we recommend obtainingthree estimates!
Table of Contents (tap to open/close)
- Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Minato Ward, Tokyo
- Roof Inspection Before Installing Solar Panels
- Subsidies and Grants Available in Minato Ward, Tokyo
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installer in Minato Ward, Tokyo
- Benefits of Introducing Solar Equipment
- Points to Consider When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions about Solar and Storage Battery Installation in Minato Ward, Tokyo
- If You Are Looking for a Solar Panel Installer in Minato Ward, Tokyo, Contact Kakeru Koumuten
- Characteristics of Minato Ward, Tokyo and Points for Solar Installation
- Service Area in Minato Ward, Tokyo
Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Minato Ward, Tokyo
Regarding why we are entrusted with solar panel installation by customers in Minato Ward, Tokyo,
“Our strengths in solar panel installation that cannot be imitated by other companies”
have received high praise from many customers.
We would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Can Also Handle Exterior Renovations Other Than Solar Panel Installation!
Issues such as leaks that occur during solar panel installation may be caused by insufficient checks on the roof and waterproofing at the installation site.
Even if one is knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside their expertise, so caution is necessary.
It is reassuring to have expertise in roofing to avoid maintenance and issues after installation!
Kakeru Koumuten is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent issues after solar panel installation!
2.Facilities Specialized in Exterior Renovation
Kakeru Koumuten has organized the following warehouses and material storage areas to provide low-cost, high-quality solar work and exterior renovations.
We have established five bases for material storage and showrooms.
In-house Ownership of Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding according to construction conditions and can assemble scaffolding in-house.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also cut costs for scaffolding work.
We own scaffolding materials for approximately 50 houses!
Even if there are height differences on the site, our in-house scaffolding team will plan the scaffolding according to the local conditions.
Storage of Materials in Our Large Warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, you canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, enabling us torespond quickly in emergencies!
Sorting and Transporting Waste Materials In-House
The installation of solar panels often involves roofing work, generating various waste materials such as paints, wood, and metals.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior Renovation Dedicated Showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are attached to the roofing materials!
Simulations for potential earnings and installation costs when introducing solar panels are also available!
Since roofing and exterior wall work often accompany projects, we also provide samples of roofing materials and models that explain the structure, allowing for detailed explanations!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having a consistent system from inquiry to project completion, Kakeru Koumuten can provide high-quality roof renovations at reduced costs.
Additionally, one representative will handle everything from the estimate to project completion.
Since the担当者 does not change, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation, exterior wall painting, to roof renovations!
4. Various Permits and Skilled Workers
We have obtained 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, and we are confident in our construction techniques.
We can also handle large-scale roof projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation work, we also provide our own施工保証 (leak warranty)!
(The施工保証 for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovations are performed. The施工保証 is separate from the manufacturer’s product warranty, and the scope and conditions vary based on the warranty details.)
Aftercare is available every year, and we send out notification DM each year.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roofing troubles and situations.
If you cannot access the roof due to height, we can utilize drones to assist!
During leak investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of your solar panels decreases due to dirt, we can also provide cleaning services with specialized brushes.
We will respond according to your 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 provide technical training so that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
Kakeru Koumuten provides not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar construction guidebook” and 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.
We compile easy-to-understand materials that include points to consider and disadvantages for customers who may not be familiar with solar construction!
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.
Confirming “Is it okay to install them directly on the current roof?” before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, which specializes in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Age | The fixing method varies depending on the roofing materials, such as slate, tiles, metal roofs, and flat roofs (rooftop waterproofing). If the remaining lifespan of the roofing material is short, we may suggest roof renovation first. |
| 2. Condition of Substrate and Waterproof Sheet | If the sheathing boards or roofing (waterproof sheet) under the roofing material are damaged, it will affect the fastening strength and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, will affect the power generation. We will create a layout diagram from the drawings and the site, and you can check it with a power generation simulation. |
| 4. Shape of the Roof and Usable Area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. The number of panels that can be installed varies depending on the size of the panels, so we will compare based on the total output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will 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 waterproofing treatment method for the fixing parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels being added. After investigating the existing roof, substrate, and load-bearing capacity, switching to lighter roofing materials may also be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will confirm the installation location of the power conditioner and storage battery, as well as the wiring route to the distribution board. The length of the wiring will also affect the cost. |
| 8. Ease of Scaffolding Setup and Delivery Routes | If there are elevation differences on the site, planning for scaffolding and the delivery routes for equipment and materials may require some ingenuity. We will also check the width of the front road and any steps on the site during the on-site survey. |
Fixing Methods and Confirmation Points 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 the fixing parts, cracks or deterioration of the slate, condition of the substrate. If deterioration is advanced, consider roof overlay (cover method) or replacement first. |
| Tile Roof | Fixed with brackets and methods suited to the type of tile (even methods that do not drill holes in the tiles will fix to the substrate) | Type and condition of the 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 framework | Type and deterioration status of the waterproof layer, waterproofing around the framework. Consider in conjunction with the timing of waterproofing work. |
If you plan to renovate the roof 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 Minato City, Tokyo
PossibleSubsidies and Grants in Minato City, Tokyo
If you are introducing solar panels or storage batteries in Minato City, Tokyo, there is a possibility that the systems from “the national government,” “Tokyo,” and your local “Minato City” may apply.
The following information is based on the official pages of each system as of October 7, 2026. The acceptance status may change depending on the budget, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Tokyo “Home Solar Power Generation Promotion Project” | Individuals, corporations, or management associations installing a new unused solar power system (output under 50kW, JET certification, etc.) in residential properties within Tokyo. The generated power must be used in the residential portion. Pre-application is required | Existing homes: 15,000 JPY per kW for up to 3.75kW (maximum 450,000 JPY), 12,000 JPY/kW for over 3.75kW to under 50kW New homes: 12,000 JPY/kW for up to 3.6kW (maximum 360,000 JPY), 10,000 JPY/kW for over 3.6kW |
For the fiscal year Reiwa 8, pre-applications are being accepted from May 29 (ends when the budget is reached). From the pre-application for Reiwa 8, submission of certificates issued by financial institutions is mandatory at the time of performance reporting. |
| Tokyo “Home Battery Installation Promotion Project” | Owners of eligible devices (batteries registered with SII) excluding national and local governments. Installation must occur between April 1, Reiwa 8 and March 30, Reiwa 11. If applying after October 1, Reiwa 8, only products registered with the national SII for Reiwa 8 are eligible | Battery package: 100,000 JPY per kWh (maximum 1,200,000 JPY per household) Additional for participating in DR demonstration (100,000 JPY per unit; 150,000 JPY per unit if energy management devices are installed) Battery unit expansion: 60,000 JPY/kWh (maximum 720,000 JPY per household) |
For the fiscal year Reiwa 8, pre-applications are being accepted from May 29. Grant applications and performance reports will be accepted starting June 30. |
| Minato Ward “Global Warming Countermeasures Subsidy Program” (Subsidy for Installation Costs of Renewable Energy and Energy-Saving Equipment) | For solar power: residents, management associations, small businesses, and individual entrepreneurs. For battery systems: only residents (must have a resident certificate in Minato Ward at the time of application). New equipment (solar power must have JET or IEC certification, battery systems must be SII registered) and must not have been applied for at the same address in the past. Application is required before the start of construction | Solar power generation system: 100,000 JPY per kW for maximum output (residents maximum 400,000 JPY, management associations, small businesses, and individual entrepreneurs maximum 1,000,000 JPY) Battery systems: 40,000 JPY per kWh for initial effective capacity (maximum 200,000 JPY) |
Applications from April 1, Reiwa 8 to January 29, Reiwa 9, with completion reports due by February 26, Reiwa 9. Please check the official page of the ward for application status. |
| National “DR Home Battery Project” (Reiwa 7 Fiscal Year Supplement) | Newly introducing 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 3/10, maximum 600,000 JPY per application). | The budget was reached on May 29, 2026, and the public offering has ended (there are no plans to reopen the public offering as stated on the official site, and applications cannot be made at this time). |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Batteries are one of the eligible facilities, but they must be combined with essential works such as insulation renovations of windows (openings) and structures; applications cannot be made for battery installation alone. Solar panels are not included as eligible facilities | Battery: 96,000 JPY per household | Ends as soon as the budget limit is reached. As of October 5, 2026, the application amount for renovations is displayed as 8% of the budget on the official website. Please check the acceptance status on the official website. |
The Tokyo solar power and storage battery subsidy requires prior application. For storage batteries applied for after October 1, 2026, only products registered with the national SII will be eligible, and the equipment requirements will change. The subsidy in Minato Ward is a prior application system that must be submitted before the construction starts. Eligibility conditions, application procedures, and the possibility of combining different systems vary, and applying does not guarantee that subsidies will be granted, so please confirm before contracting and starting construction.
Kakeru Koumuten will provide guidance on eligibility conditions and application periods for each system after confirming them.
National Subsidy “DR Home Storage Battery Project (Support Project for the Introduction of Home Storage Systems for DR Resource Implementation)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program targets those who are newly introducing registered storage systems that can be utilized for demand response (DR), and in the fiscal year 2025 supplementary project, the subsidy amount was determined based on a standard amount of 34,500 yen per 1 kWh of initial effective capacity, with a subsidy rate of up to 30% and a maximum of 600,000 yen per application. There are conditions such as that contracts or orders made before the grant decision are not eligible.
However, the fiscal year 2025 supplementary application amount reached the budget on May 29, 2026, and the public recruitment has ended. The official website also states that there are no plans to reopen public recruitment, and applications are currently not possible. Please check the official website for future public recruitment.
Furthermore, there are currently no subsidies confirmed for the installation of solar panels on existing homes.
👉 Click here for the official website of the DR Home Storage Battery Project
Tokyo “Promotion Project for the Introduction of Solar Power Generation in Homes”
This subsidy is for those who are newly installing unused solar power generation systems in residential homes in Tokyo. The simultaneous installation of storage batteries is not a condition.
● Existing Homes: For systems below 3.75 kW, 150,000 yen per kW (maximum 450,000 yen); for systems above 3.75 kW and below 50 kW, 120,000 yen per kW.
● New Homes: For systems below 3.6 kW, 120,000 yen per kW (maximum 360,000 yen); for systems above 3.6 kW and below 50 kW, 100,000 yen per kW.
● Additional amounts are available for the installation of rooftop frames and waterproofing work.
The target is to install unused panels with an output of less than 50 kW that have obtained JET certification, for use in residential parts of homes in Tokyo. The process involves making a prior application and then applying for the grant after installation. Starting from the prior application for fiscal year 2026, submission of a certificate issued by a financial institution during the performance report is now mandatory.
The official page of Tokyo states that pre-registration is being accepted from May 29, Reiwa 8. It will end once the budget is reached, so please check the official page for the registration status.
👉 Here is the official page of Tokyo (Cool Net Tokyo)
Tokyo’s “Household Battery Installation Promotion Project”
This is a subsidy for the installation costs of battery systems aimed at increasing self-consumption of electricity generated by solar power and improving energy independence during emergencies.
●Battery package: 100,000 JPY per kWh (maximum 1,200,000 JPY per household)
●Additional for participating in DR demonstration: 100,000 JPY per unit (150,000 JPY per unit if energy management equipment is installed)
●Expansion of battery units: 60,000 JPY per kWh (maximum 720,000 JPY per household)
Eligible applicants are owners of the subsidized equipment (excluding national and local governments), and installation must occur between April 1, Reiwa 8 and March 30, Reiwa 11. If pre-registration is done after October 1, Reiwa 8, only products registered in the Reiwa 8 fiscal year by the national SII will be eligible.
The official page of Tokyo states that pre-registration is being accepted from May 29, Reiwa 8. For detailed information, including conditions for combination with solar power generation, please check the official page.
👉 Here is the official page of Tokyo (Cool Net Tokyo)
Minato Ward “Global Warming Countermeasure Subsidy System” (Subsidy for Installation Costs of Renewable Energy and Energy-Saving Equipment)
This subsidy is for those who install solar power systems and battery systems in residential areas within the ward. The solar power system is available to residents, management associations, small businesses, and individual entrepreneurs, while the battery system is available only to residents (management associations and businesses are excluded from the battery system eligibility). Applications must be made before the start of construction.
●Solar power system: 100,000 JPY per kW of maximum output (residents have a maximum of 400,000 JPY, management associations, small businesses, and individual entrepreneurs have a maximum of 1,000,000 JPY)
●Battery system: 40,000 JPY per kWh of initial effective capacity (maximum 200,000 JPY)
The equipment must be new, with the solar power system requiring JET or IEC certification, and the battery system must be registered with the SII (Environmental Co-Creation Initiative). There are conditions such as being ineligible if subsidies have been received at the same address in the past.
The official page of Minato Ward states that applications are accepted until January 29, Reiwa 9, and completion reports are due by February 26, Reiwa 9. The registration status may change, so those considering applying should check the official page early.
👉 Here is the official page of Minato Ward
Solar Panel Installation & Battery Installation Price List
⇧Service Menu | For costs related to solar panel removal and hot water heater removal, click here
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and storage batteries should be confirmed by separating them into “Equipment Costs (Device Costs)” and “Construction Costs.”
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and Storage Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatt). Storage batteries are compared based on the amount of electricity they can store, expressed in kWh (kilowatt-hour).
The amount of kW that can be installed on the roof varies for each house based 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 priced at 800,000 JPY to 1,200,000 JPY for 3 to 5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6 to 10 kW. (These are approximate prices and may vary based on factors such as wiring length, scaffold 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) are specified. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls in conjunction with the battery. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range 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 securing (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, 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 included for applications to the power company, certification application for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If it is simultaneous with roof work or exterior painting, check that the same scope and quantity are not double counted. |
| 9. Removal and Disposal | Whether the removal of existing solar thermal water heaters 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 warranty and workmanship warranty. |
If the capacities differ, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome comparisons, so if you bring estimates from other companies, we will explain the differences item by item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can obtain 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 get an estimated quote and financial simulation!
*The simulation results are estimates. Actual financial results may vary based on assumptions such as electricity rates, self-consumption ratios, selling prices, and costs for equipment inspection or replacement.
Customer 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 |
| Base Mounting Hardware Used |
| Niigata Manufacturing/Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Details |
| Fixed using catch type hardware gripping the horizontal metal roof (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the subsidy being granted, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The subsidy amount and recovery estimates are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| About 3 days |
| Completion Month |
| April 2025 |
| Inquiry Details |
| I am considering the introduction of solar panels and storage batteries. I heard that subsidies are available, and I would like to know how much will be granted. |
Our Proposal
We visited to provide an estimate and created a layout diagram for the solar panels from the drawings!
The layout diagram shows the arrangement of solar panels when placed on the roof.
Since we can also determine the installation capacity, it allows for power generation simulations and financial simulations.
We understood the expected subsidy amount, so we explained it to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Minato, Tokyo
There are many solar panel installation contractors available in Minato Ward, Tokyo, and you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s confirm the following 4 points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and aftercare services
● Obtain estimates from multiple contractors (3 companies is a guideline)
● Check if they provide support for subsidy applications
By confirming the above 4 points, you will be able to choose a reliable contractor.
Have knowledge not only about solar panels but also about roofs
Defective installation of solar panels may be caused by a lack of knowledge and confirmation 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 confirmation of roofs and waterproofing
・Solar panels installed on a deteriorated roof causing leaks
・Solar panels installed on a roof with a short lifespan, requiring removal and renovation within a few years
・Misjudgment of the type of waterproofing leading to incorrect treatment and resulting in leaks
and more
When installing solar panels, understanding the condition and type of the existing roof allows you to avoid unnecessary expenses and unforeseen troubles.
▶ Go to “Roof Confirmation Before Installing Solar Panels” in this article
Confirm the existence of warranties and aftercare services
When choosing a solar equipment 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.
Solar panels and battery storage units come with manufacturer warranties, but also check for the existence of installation warranties in case leaks occur after installation!
For contractors that offer installation warranties, if leaks occur after installation within the warranty period and conditions, they may cover the repairs under the warranty.
Additionally, some contractors provide aftercare services separate from warranties, so be sure to check if the contractor you are considering has aftercare services.
Since abnormalities or damages on the roof may not be visible, you might not notice them yourself.
By conducting inspections during aftercare, you can easily detect abnormalities early, preventing major repairs or breakdowns!
At Kakeru Koumuten Co., Ltd., the installation of solar panels comes with a leak warranty as part of the workmanship warranty. (The warranty for solar panel installation is 10 years, and depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof remodeling is performed.)
We also conduct aftercare maintenance and send out annual DM!
After checking the DM, if you wish, we will visit you for aftercare maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting the installation of solar panels, let’s obtain estimates from multiple contractors.
Even for the same manufacturer and the same construction content, costs may vary, and warranties and after-sales services may differ.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request your desired contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates,
check the following:
「Confirmation of estimate items」
「Types of solar panels」
「Warranties and after-sales services」
and make a detailed comparison! Avoid judging solely based on cost, as using lower-grade materials or skipping processes can reduce costs!
▶ Go to “Breakdown of installation capacity, equipment, and construction costs” in this article
Check if they provide support for subsidy applications
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 grant may not be awarded.
Since there are systems that require prior application, such as the Tokyo Metropolitan Government’s subsidies, 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 subsidies, prior application is required) before proceeding with the construction!
For Tokyo’s subsidies, after installation, a grant application and performance report must be submitted, and the flow will be awarded after review! (The flow of procedures varies by system)
▶ Go to “Subsidies and grants that may be applicable in Minato Ward, Tokyo” in this article
Benefits of Introducing Solar Equipment
The benefits of introducing solar panels are as follows!
Benefit 1: Economic Benefits
The biggest advantage of introducing solar panels is the economic benefit!
The selling price of electricity has decreased compared to 10 years ago, but by consuming the electricity generated, you can reduce the amount of electricity purchased from the utility company and gain benefits!
As electricity costs rise, the ability to cover your consumption with solar power becomes attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
Furthermore, the selling price (FIT) for residential use (less than 10kW) will be set as “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 fiscal year 2026. After the 5th year, it is likely to be more advantageous to use it at home (self-consume) rather than selling it, so combining it with a storage battery is also an option.
👉 Ministry of the Environment | For purchase prices and periods, click here
Advantage 2 Subsidies can be utilized!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the conditions, you may be able to utilize subsidies!
Reducing the actual burden amount through subsidies is a significant advantage!
In Minato Ward, there is a possibility of being eligible for the national, Tokyo Metropolitan, and Minato Ward systems. The application for Minato Ward’s subsidy must be submitted before the start of construction, and the application deadline is stated as January 29, 2027 (please check the acceptance status for each system).
Advantage 3 Environmentally friendly!
Solar power generation has low carbon dioxide emissions and can reduce dependence on fossil fuels, contributing to the mitigation of global warming.
Solar panels themselves do not produce noise or exhaust gases during the generation process, making them an environmentally friendly method of power generation. (However, devices like power conditioners do have operational noise.)
Advantage 4 Heat insulation effects are expected!!
By installing panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, this can help reduce the temperature of the roof, providing expected heat insulation effects!
（This does not improve the insulation performance of the building itself）
Benefit 5 Electricity can be used even during power outages!!
If a storage battery is installed, it is possible to use electricity even during emergencies such as power outages!
Even without a storage battery, if you have a power conditioner with autonomous operation capability, you may be able to use electricity from a dedicated outlet during daytime generation.
（The devices, output, and duration that can be used during a power outage vary depending on the model and wiring method）
What points should be noted when introducing solar power generation?
Next, we will explain the “three points to note” when installing solar panels!
Point 1 Maintenance costs can be incurred
A particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof remodeling 10 to 20 years later, there will be costs for removing and reattaching the solar panels.
If the existing roof is deteriorated, it is reassuring to remodel it with durable roofing materials before installing solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to deterioration of the storage battery.
It would be reassuring to ask for a simulation considering maintenance costs before introducing solar panels!
Point 2 The risk of leaks increases depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but in methods that fix hardware with screws to the roofing material or substrate, waterproofing of the fixed parts is crucial.
In methods that create holes in the roof, the risk of leaks inevitably arises.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, replacing the roofing material with a metal roof and fixing the solar panels using the catch method is also an option. (The catch method has compatibility conditions between the roofing material and hardware, and cannot be used with all metal roofs)
Catch-type base metal fittings for horizontal metal roofs
Note 3: The roof will become heavier
Since solar panels will be installed, the roof will become heavier. After investigating the existing roof, substrate, and load-bearing capacity, switching to a lighter roof may also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
Choosing Point 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 it is better to generate more electricity!
Solar panels come in various sizes and outputs depending on the manufacturer.
A panel with an output of 350W and a panel with an output of 400W may seem like 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,” meaning the number of panels that can be installed on the same roof may differ due to the size of the panels.
400W×15 panels = 6kW (total output of the roof)
350W×20 panels = 7kW (total output of the roof)
As shown above, even if the output of one panel is lower, the total output of the roof may be higher!
It is important to consider the total output of the roof rather than the output of a single panel!
*The above is a calculation of total output (kW). The actual power generation (kWh) will vary depending on conditions such as the orientation, slope, and shading of the roof.
Choosing Point 2: Compare by Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases after 10 or 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output guarantee value is a standard figure for warranty purposes and does not indicate the actual degradation rate or power generation itself.
Choosing solar panels without considering the degradation rate can lead to regrets, so it is important to take it into account!
Choosing Point 3: Compare by Warranty Period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
For output warranties, some manufacturers offer a 30-year warranty while others provide a 10-year warranty, so it varies widely!
It’s always better to have a longer warranty, so let’s check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Minato City, Tokyo
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Minato City, Tokyo. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Minato City, Tokyo?
The cost varies depending on the installation capacity, equipment, and condition of the roof. In the above construction example (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
Guidelines for costs by capacity are published 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 power and storage battery installation in Minato City, Tokyo?
As of October 7, 2026, Tokyo’s “Household Solar Power Generation Promotion Project” (for existing homes, 15,000 yen per kW for systems under 3.75kW, with a maximum of 450,000 yen) and “Household Storage Battery Promotion Project” (100,000 yen per kWh for storage batteries, with a maximum of 1.2 million yen per household) are accepting pre-applications starting May 29, 2026, as stated on the official page of Tokyo (Cool Net Tokyo). In Minato City, the Global Warming Countermeasures Subsidy System (for solar power systems, 100,000 yen per kW of maximum output with a cap of 400,000 yen for residents, and for storage systems, 40,000 yen per kWh of initial effective capacity with a cap of 200,000 yen) can be applied for before the start of construction until January 29, 2027, as stated on the official page of Minato City. The national DR household storage battery project has ended its public recruitment.
Since the application status may change, please refer to the subsidy and grant section and consult with us before signing a contract.
Can I apply for subsidies after the construction is completed?
This depends on the system. Tokyo’s subsidies require pre-application, and Minato City’s grants also require application before the start of construction. Conditions such as whether you can contract and start construction before applying vary by system, so please confirm before signing a contract.
The order of procedures varies by system, so please check before signing a contract and starting construction.
Can solar panels be installed on slate roofs? I’m worried about leaks.
Installation on slate roofs is possible, but it is necessary to check the condition of the roofing material and substrate. The method of securing the panels varies by construction method, and when using a method that secures brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is very important.
Kakeru Koumuten Co., Ltd. is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation. If deterioration is progressing, we can also propose methods such as roof overlay (cover method) or re-roofing before installation.
My roof is old. Should I do a roof renovation first?
It depends on the condition of the roof. If a roof renovation is needed within 10 to 20 years after installation, there will be additional costs for removing and reinstalling solar panels. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with durable roofing materials before installation.
Please consult us about the installation process after 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 subsidy for storage batteries in Tokyo (for Reiwa 8, it is 100,000 yen per kWh, with a maximum of 1,200,000 yen per household) aims to increase self-consumption of electricity generated by solar power. In Minato Ward, residents are eligible for subsidies for storage systems (management associations and businesses are excluded). You can compare “solar only” and “solar + storage battery” in a revenue simulation.
How many kW can be installed on my roof? Is it okay for a north-facing roof or one that has shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten, we create a layout diagram based on the drawings and on-site survey, and we will provide you with the installation capacity and power generation simulation.
Minato Ward has areas with highlands facing northwest and lowlands/reclaimed land facing southeast towards Tokyo Bay, so the shape, orientation of the roof, and the shadows cast by surrounding buildings will differ for each house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
For the above construction example (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roofing work is done simultaneously or depending on the shape of the roof and installation capacity.
Please note that there will be additional time required for applications for subsidies and electricity companies, so please consult us as soon as possible.
What is the current selling price (FIT)?
For residential use (less than 10 kW), from certifications after October 2025, the first 4 years will be 24 yen/kWh, and from the 5th to the 10th year, it will be 8.3 yen/kWh, and the same prices will apply for the 2026 fiscal year.
The idea is to recover initial costs more quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides a revenue simulation that considers loan interest rates and electricity prices.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-maintenance notices via DM and visits customers who request 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 company in Minato City, Tokyo, please consult Kakeru Koumuten
Our company handles many exterior renovations, including solar panels, roof work, and exterior wall work in Minato City, Tokyo.
We receive requests from many customers, including renovation companies and real estate agencies, who have contacted us!
Kakeru Koumuten Co., Ltd. promises “high-quality renovations at low costs”, and we have received positive feedback from many customers.
We continue to update our annual construction achievements, 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 (cover method) and re-roofing but also partial roof repairs, exterior wall painting, and exterior wall overlay methods.
We are 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 recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide optimal solutions for specific requests.
We will never propose unnecessary work that prioritizes profit!
We always stand in the customer’s position and propose the best construction plan!
We are confident that we will not lose in terms of cost, quality, and planning compared to other companies in exterior work!
We welcome competitive quotes because we are confident!
Estimates are completely free, and if our company is inferior to others, you are free to decline!
Characteristics of Minato City, Tokyo, and Points for Solar Work
Minato Ward covers an area of 20.36 square kilometers, located in the southeastern part of Tokyo, facing Tokyo Bay. The northwestern area is a high plateau at the edge of the Musashino Plateau, while the southeastern area consists of lowlands facing Tokyo Bay and reclaimed land in Shibaura, with the high plateau being the most undulating terrain among the 23 wards. We have summarized the characteristics of the terrain in Minato Ward, Tokyo, and points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Minato Ward, Tokyo, and points for solar construction
■ Undulating high plateau, lowlands, and reclaimed land. Check scaffolding and delivery routes for each site
According to the official page of the ward, the area is divided into five districts: Shiba, Azabu, Akasaka, Takanawa, and Shibaura Konan, with flat land in the central area of the Furukawa river basin. In the high plateau, if there are height differences on the site or depending on the width and slope of the front road, the way scaffolding is set up and the delivery routes for panels and storage batteries will change. In lowlands and reclaimed land, the height of surrounding buildings will affect the shadows cast. At Kakeru Koumuten, our own scaffolding team plans the scaffolding according to the site, creates layout diagrams from the drawings and on-site surveys, and you can confirm this with a power generation simulation.
■ Check the flood hazard map. Be cautious about the installation location of equipment
The flood hazard map for Minato Ward assumes a total rainfall of 690 millimeters and a maximum hourly rainfall of 153 millimeters, overlaying the predicted flood areas of the Jonan district river basin, Sumida River, and Shinkawaguchi River basin, as well as the internal river basin of Koto. The impact of water damage may vary depending on where the power conditioner and storage battery are installed, whether indoors or outdoors, separate from the panels on the roof. Please check the flood assumptions for your residence on the ward’s hazard map and consult us about the installation location and height, in accordance with the installation conditions of the manufacturer you are using.
■ Roof types and ages vary from house to house. Check the roof and waterproofing before installation
Even within the same ward, the types of roofs, ages, and shapes of the sites vary from house to house. The subsidies in Minato Ward cover solar power generation systems for management associations, small and medium-sized enterprises, and individual business operators, and the shape of the roof and the capacity that can be installed will change depending on the type of building. At Kakeru Koumuten, we will check the type and condition of the roof and the situation of the site before installation and propose methods for securing, waterproofing, and planning scaffolding.
■ The annual sunshine hours at the Tokyo Observatory is about 1,927 hours
According to the Japan Meteorological Agency’s average values (1991–2020), the annual sunshine hours at the Tokyo Observatory is about 1,927 hours, with January (about 193 hours) being the most, and June during the rainy season (about 124 hours) being the least. (This is a reference value, not an observation value within Minato Ward)
The power generation in Minato Ward can also change due to shadows from surrounding buildings, so conducting a year-round power generation simulation and selecting the capacity of the storage battery to match the times of high electricity usage are key points.
Our company handles many exterior construction and solar projects in Minato 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 about any sudden troubles!
Service Area in Minato Ward, Tokyo
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Minato Ward, Tokyo
Akasaka, Minato Ward / Azabu Juban, Minato Ward / Azabu Dai, Minato Ward / Azabu Nagasaka-cho, Minato Ward / Azabu Tanukikoji, Minato Ward / Atago, Minato Ward / Kaigan, Minato Ward / Kita Aoyama, Minato Ward / Konan, Minato Ward / Shibaura, Minato Ward / Shiba Park, Minato Ward / Shiba Daimon, Minato Ward / Shiba, Minato Ward / Shirokanedai, Minato Ward / Shirokane, Minato Ward / Shinbashi, Minato Ward / Takanawa, Minato Ward / Odaiba, Minato Ward / Toranomon, Minato Ward / Nishi Azabu, Minato Ward / Nishi Shinbashi, Minato Ward / Hamamatsucho, Minato Ward / Higashi Azabu, Minato Ward / Higashi Shinbashi, Minato Ward / Mita, Minato Ward / Minami Aoyama, Minato Ward / Minami Azabu, Minato Ward / Moto Akasaka, Minato Ward / Moto Azabu, Minato Ward / Roppongi, Minato Ward
・For exterior wall painting in Minato, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・For roof renovations in Minato, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・For exterior renovations in Minato, Tokyo, trust Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd. project achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. service menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・Explaining the importance of comparison estimates and key points!
・12 major manufacturers of solar power generation! 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 installing solar power generation? Key points for site selection included!
・Find out about solar power generation estimates here!
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contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
