Leave the installation of solar panels in Chiyoda, Tokyo to Kakeru Koumuten Co., Ltd.!
For solar panel and storage battery installation in
Chiyoda, Tokyo,
Kakeru Koumuten is at your service!
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 storage battery installations that consider roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Chiyoda”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Chiyoda”
We will also explain the above three points!
Installing solar panels carries risks, such as “the occurrence of leaks,” and other troubles.
To ensure you have no regrets about your solar panel installation, we recommend obtaining around three estimates!
Table of Contents (tap to open/close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Chiyoda, Tokyo
- Roof Inspection Before Installing Solar Panels
- Subsidies and Grants That May Be Applicable in Chiyoda
- 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 Chiyoda, Tokyo
- Benefits of Introducing Solar Equipment
- Points to Note When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions About Solar and Storage Battery Installation in Chiyoda
- If You Are Looking for a Solar Panel Installer in Chiyoda, Contact Kakeru Koumuten
- Characteristics of Chiyoda, Tokyo and Points for Solar Installation
- Service Area in Chiyoda, Tokyo
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Chiyoda, Tokyo
The reasons why our company is entrusted with solar panel installation by customers in Chiyoda, Tokyo include
one reason being that “Kakeru Koumuten serves Kanagawa and Tokyo as its service areas”,
and we have “unique strengths in solar panel installation that cannot be imitated by other companies”, which has received high praise from many customers.
so we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Also Handle Exterior Renovations Aside from Solar Panel Installation!
Problems such as leaks that occur during solar panel installation may be caused by insufficient checks on the roof and waterproofing at the installation site.
Even if you are knowledgeable about solar panels, there may be cases where the roof and waterproofing at the installation site are outside your expertise, so caution is necessary.
It is reassuring to have expertise in roofing to avoid maintenance issues 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.Facilities Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. 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 centered around Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding based on construction conditions and can assemble scaffolding in-house.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also cut costs for scaffolding work.
We own scaffolding materials for approximately 50 single-family homes!
Even in the urban area of Chiyoda Ward, our in-house scaffolding team will plan scaffolding according to the site conditions.
Storage of Materials in Our Large In-house Warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, you can purchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we can respond quickly in emergencies!
In-house sorting and transportation of waste materials
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior renovation dedicated showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are attached to the roofing materials!
We can also provide simulations for potential earnings and installation costs when introducing solar panels!
Since roofing and exterior wall work often accompany each other, we also have samples of roofing materials and models that show the structure, allowing us to provide detailed explanations!
3.All work performed by our own team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having Kakeru Koumuten handle everything from inquiries to project completion in a consistent manner, we can keep costs down and provide high-quality roof renovations.
Additionally, one representative will assist you from the estimate to the completion of the work.
Since the same person will handle sales and construction management, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation to exterior wall painting and roof renovations!
4. Various Permits and Skilled Workers
We have obtained construction industry permits and industrial waste collection and transportation permits!
We also have nationally certified sheet metal and painting technicians on staff, and we are confident in our construction techniques.
We are capable of handling large-scale roof projects such as those for factories!
5. Warranty and Aftercare Maintenance
In addition to the manufacturer’s warranty for solar panel installation work, we also provide our own construction warranty (leakage warranty)!
(The construction warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovations are performed. The construction warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary based on the warranty details.)
Aftercare maintenance 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 a drone to assist!
During leak investigations, we can also conduct surveys using a thermal imaging camera.
If the power generation of solar panels decreases due to dirt or other factors, we can provide cleaning services using a specialized brush.
We will respond according to your preferences.
7. Human Resource Development
To improve skills, we create various roofing models and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly provide technical training 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.
For customers who are not familiar with solar construction, we compile easy-to-understand materials that include points to consider and disadvantages!
We encourage you to obtain comparative estimates and compare them with other companies’ plans!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 or 30 years.
Confirming “Is it okay to install them directly on the current roof?” before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, which specializes in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Age | The fixing method varies depending on the roofing materials such as slate, tiles, metal roofs, and flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest roof renovation first. |
| 2. Condition of the Substrate and Waterproof Sheet | If the sheathing boards or roofing (waterproof sheet) beneath the roofing material are damaged, it can affect the fastening strength and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, can affect power generation. We will create a layout diagram from the drawings and the site, and you can check it with a power generation simulation. |
| 4. Shape of the Roof and Usable Area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. Since the number of panels that can be installed varies depending on the panel size, we will compare based on the total output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will confirm whether the method involves drilling holes in the roofing material for fastening or using brackets to secure the roofing material. The fixing method varies by technique, so please check the waterproofing treatment method for the fixing parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels. After investigating the existing roof, substrate, and load capacity, switching to lighter roofing materials may also be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will check the installation 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 the cost. |
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 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 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 carry out roof renovations 10 to 20 years after installation, there will be additional costs for the removal and reinstallation of solar panels. If the roof is deteriorating, renovating to a highly durable roofing material before installation may help reduce costs in the long run.
Kakeru Koumuten Co., Ltd. specializes in roofing work and can also handle the removal and reinstallation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Chiyoda, Tokyo
Subsidies and Grants That May Be Applicable inChiyoda, Tokyo
If you are introducing solar panels or storage batteries in Chiyoda, Tokyo, there may be applicable systems from “the national government,” “Tokyo,” and “Chiyoda City.”
The following information is based on the official pages of each system as of October 7, 2026. The application status may change due to budget and recruitment periods, 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 “Reiwa 8 Year Household Solar Power Generation Promotion Project” (Cool Net Tokyo) | New installation of certified solar modules in residential properties or their premises within the Tokyo area, with a system capacity of less than 50kW. Pre-application before installation is required. | Existing homes: 150,000 JPY/kW for up to 3.75kW (maximum 450,000 JPY), 120,000 JPY/kW for over 3.75kW New homes: 120,000 JPY/kW for up to 3.6kW (maximum 360,000 JPY), 100,000 JPY/kW for over 3.6kW (Additional costs for mounting frames, waterproofing work, and renovation defect insurance may apply) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 to March 30, 2029 |
| Tokyo Metropolitan Government “Reiwa 8 Year Household Storage Battery Promotion Project” (Cool Net Tokyo) | New installation of storage batteries in residential properties within the Tokyo area, with the requirement that they are SII registered devices. This project is intended for simultaneous installation with solar power, but applications can be made for storage batteries alone. Pre-applications after October 1, 2026 will only be eligible for SII registered products for Reiwa 8. | Storage battery package: 100,000 JPY/kWh (maximum 1,200,000 JPY per household) Expansion of storage battery units: 60,000 JPY/kWh (maximum 720,000 JPY per household) (Additional incentives for participating in DR demonstrations may apply) |
Pre-application: From May 29, 2026 Grant application and performance report: From June 30, 2026 |
| Chiyoda Ward “Energy Conservation Renovation Subsidy Program” Reiwa 8 Year | Owners of existing buildings (single-family homes, condominiums, etc.) within the ward, or those who have obtained consent from the owners. The installation of unused equipment is required, with solar power modules needing to be certified by JETPVm, and storage systems must meet SII designated subsidy equipment requirements. Pre-application before construction is required, and construction must be carried out after receiving the grant decision notification. | Solar power generation & storage systems: 20% of eligible expenses (maximum 1,000,000 JPY) | Application deadline: February 15, 2027 (first-come, first-served) Applications for this fiscal year have temporarily ended due to reaching the budget limit. Combination with other subsidies is possible. |
| National “DR Home Storage Battery Project” (Reiwa 7 Year Supplement) | New installation of household storage systems that can be utilized for DR (demand response) with registered products. | Calculated based on an initial effective capacity of 34,500 JPY per kWh (subsidy rate within 30% and a maximum of 600,000 JPY per application). | The budget was reached on May 29, 2026, and the public offering has ended. (Applications cannot be made at this time) |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Storage 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 the installation of storage batteries alone. Solar panels are not included as eligible facilities. | Storage battery: 96,000 JPY per household | Ends once the budget limit is reached. Please check the official website for the application status. |
The Tokyo subsidy requires pre-application before installation, while the Chiyoda Ward grant requires application and notification of grant decision before construction. If construction begins beforehand, it may become ineligible for both. Applying does not guarantee that the grant will be awarded. The budget for Chiyoda Ward for Reiwa 8 has been reached, and applications are temporarily closed, so please check the ward’s official page for the resumption of applications and future systems. The Chiyoda Ward grant can be combined with other subsidies, but a copy of the notification for the combined subsidy must be submitted upon completion of the work. Procedures differ by system, so please confirm before contracting and starting construction.
Kakeru Koumuten will guide you on eligibility conditions for each system after confirming them.
Tokyo “Reiwa 8 Household Solar Power Introduction Promotion Project”
In Tokyo, subsidies are provided for those installing solar power systems in residential homes through Cool Net Tokyo. The target is systems using certified solar modules installed newly in residential homes or on their premises, with a capacity of less than 50kW. A pre-application before installation is required.
For existing homes, the subsidy amount is 150,000 yen/kW for systems up to 3.75kW (maximum 450,000 yen), and 120,000 yen/kW for systems exceeding 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. Please check the official page for details on eligible equipment, conditions, and budget status.
👉 Cool Net Tokyo | Official page for solar power is here
Tokyo “Reiwa 8 Household Storage Battery Introduction Promotion Project”
Tokyo is also providing subsidies for newly installed storage batteries in residential homes. The subsidy amount is 100,000 yen per 1kWh of storage battery package (maximum 1,200,000 yen per household), and for additional storage battery units, it is 60,000 yen per 1kWh (maximum 720,000 yen per household), 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 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 already started from June 30, 2026.
👉 Cool Net Tokyo | Official page for storage batteries is here
Chiyoda Ward “Energy Conservation Renovation Subsidy System”
In Chiyoda Ward, a “Energy Conservation Renovation Subsidy Program” is implemented for those who are renovating existing buildings within the ward to install energy-saving equipment. For residential properties (single-family homes, condominiums, etc.), the solar power generation system and storage system are eligible for 20% of the eligible expenses (up to 1,000,000 yen). The installation of unused equipment is a condition, and for solar power generation, modules certified by JET (Japan Electrical Safety & Environment Technology Laboratories) with JETPVm certification (or those recognized by the ward as having equivalent performance) are eligible, while the storage system must be one designated as eligible equipment by SII (Environmental Partnership Organization) (or those recognized by the ward as having equivalent performance).
Applications must be submitted before construction begins, and construction should start only after receiving the grant decision notification. Applications are accepted on a first-come, first-served basis, with the deadline being February 15, 2027; however, the budget for the fiscal year 2026 has been reached, and applications are temporarily closed. It can be combined with other subsidies, so a copy of the confirmation notification for the combined subsidies must be submitted upon completion of the work. Please check the ward’s official page for information on the resumption of applications and future programs.
👉 Click here for the Chiyoda Ward official page (Energy Conservation Renovation Subsidy Program)
National Subsidy “DR Home Storage Battery Project (Support Project for Home Storage System Introduction for DR Resource Implementation)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program targets those who are newly introducing registered storage systems that can be utilized for demand response (DR), and in the fiscal year 2025 supplementary budget, the subsidy amount was determined based on a standard amount of 34,500 yen per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum of 600,000 yen per application. There are 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 recruitment has ended (the previous fiscal year’s supplementary budget also ended public recruitment on July 2, 2025). Currently, applications cannot be submitted, so please check the official site for future public recruitment information.
Additionally, there are currently no subsidies confirmed for the installation of solar panels on existing homes.
👉 Click here for the official site of the DR Home Storage Battery Project
Solar Panel Installation & Storage Battery Installation Price List
⇧Service Menu | For Costs of Solar Panel Installation and Battery Installation, Click Here
⇧Service Menu | For Costs of Solar Panel Removal and Water Heater Removal, Click Here
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and batteries should be confirmed by separating them into “Equipment Costs (Device Costs)” and “Construction Costs.”
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatts). Batteries are compared based on the amount of electricity they can store, measured in kWh (kilowatt-hours).
The amount of kW that can be placed on the roof varies for each house based on the shape, orientation, and size of the roof. Kakeru Koumuten Co., Ltd. creates layout diagrams from blueprints and on-site surveys to provide the installation capacity.
On our pricing page, we list solar panels as approximately 800,000 JPY to 1,200,000 JPY for 3-5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6-10 kW. (These are just estimated amounts and can vary based on wiring length, scaffolding range, existing roofing materials, panel layout, etc.)
▶ Service Menu | For Costs of Solar Panel Installation and Battery Installation, Click Here
Items to Confirm in the Estimate (Cost Confirmation)
When comparing estimates, it’s common to compare different capacities and equipment. Please check if the following items are clearly stated in each company’s estimate!
| 1. Solar Panels | Manufacturer, model number, output per panel (W), number of panels, total installation capacity (kW) should be specified. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also confirm if it is a type that controls the battery together. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range usable during a power outage (whole house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of the hardware suitable for the roofing material and the method of securing it (whether it involves drilling holes or clamping). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, and whether there is a monitor to check the power generation amount. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at the fixed parts, and whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | How much support is included for applications to the power company, 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 counted twice. |
| 9. Removal and Disposal | Whether the removal of existing solar thermal water heaters and old panels, as well as disposal costs for waste materials, are included. |
| 10. Tax Classification and Warranty | Whether prices are tax-inclusive or tax-exclusive, conditions under which additional costs may arise, and details and duration of manufacturer and workmanship warranties. |
If the capacities differ, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome comparisons, so if you bring estimates from other companies, we can explain the differences item by item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can obtain a rough estimate and a profit simulation for up to 30 years!
If you know the total installation capacity of solar panels on the roof and the capacity of the battery, you can get a rough estimate and profit simulation!
*The simulation results are approximate. 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 Testimonials
-
customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
-
customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
-
customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
-
customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
-
customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
-
customer reviews
Higashiyamato City, Tokyo | We received reviews about exterior painting and roof overlay (cover method)!
Case Studies of Solar Panel Installation
| Work 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 Sales / Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Arrangement |
| 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 grant being provided, the actual burden amount is approximately 1,000,000 JPY Expected recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant amount and recovery estimate are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| About 3 days |
| Completion Month |
| April 2025 |
| Inquiry Details |
| I am considering the installation of solar panels and storage batteries. I heard that grants are available, and I would like to know how much can be provided. |
Our Proposal
We visited to provide an estimate and created a layout diagram for the solar panels from the drawings!
The layout diagram shows the arrangement of solar panels when placed on the roof.
Since we can also determine the installation capacity, it allows for power generation simulations and financial simulations.
We have also understood the expected amount of the grant, so we explained it to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Chiyoda, Tokyo
There are many solar panel installation contractors available in Chiyoda, 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 four points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and after-sales maintenance
● Obtain estimates from multiple contractors (three companies is a guideline)
● Check if they provide support for subsidy applications
By confirming the above four points, you will be able to choose a reliable contractor.
Knowledge about roofs as well as solar panels
Improper installation of solar panels can be caused by a lack of knowledge and verification regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient verification of roofs and waterproofing
・Solar panels were installed on a severely deteriorated roof, resulting in 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 processing 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 Verification Before Installing Solar Panels” in this article
Confirm the existence of warranties and after-sales maintenance
When choosing a solar installation contractor, let’s confirm the existence of warranties. It is important to check not only the duration of the warranty but also the scope of coverage, disclaimers, 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 respond under the warranty, provided it is within the warranty period and conditions.
Additionally, some contractors offer after-sales service separate from warranties, so be sure to check if the contractor you are considering has after-sales service.
Since changes or damages on the roof may be in areas that are not visible, there is a possibility that customers may not notice them themselves.
By conducting inspections during after-sales maintenance, you can easily prevent major repairs or breakdowns by discovering issues 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 solar panel installation, be sure to obtain estimates from multiple contractors.
Even for the same manufacturer and the same work 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 preferred contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check the following:
“Check the estimate items”
“Type of solar panel”
“Warranties and after-sales services”
Make sure to compare these details carefully! If the quality of the auxiliary materials is low or if steps are skipped, costs can be reduced, so avoid making judgments based solely on price!
▶ Go to “Breakdown of Installation Capacity and Equipment/Construction Costs” in this article
Check if they provide support for subsidy applications
There may be subsidies available for solar panel installations and battery installations, but if the order of procedures is incorrect or if there are deficiencies in the documents, the subsidy may not be granted.
Some systems require personal applications and cannot be handled by the contractor, and some require pre-application before installation, so it is reassuring to choose 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, pre-application before installation; for Chiyoda Ward’s grants, application and notification of grant decision before construction) before proceeding with the work!
In the case of subsidies in Tokyo, the process involves submitting a grant application and performance report after the completion of the work, which will be granted after a review! (The procedure may vary depending on the system)
▶ To “Subsidies and Grants that may be applicable in Chiyoda Ward” within this article
Benefits of Introducing Solar Power Equipment
The benefits of introducing solar panels are summarized in the following five points!
Benefit 1: Economic Benefits
The biggest benefit of introducing solar panels is the economic advantage!
Although the selling price of electricity has decreased compared to ten 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 plan to use the generated electricity at night, installing a storage battery is essential!
Furthermore, the selling price (FIT) for residential use (under 10kW) will be set at “24 yen/kWh for the first four years, and 8.3 yen/kWh from the fifth to the tenth year” for certifications after October 2025, and the same price will apply for the 2026 fiscal year. After the fifth year, it is often more advantageous to use it at home (self-consumption) rather than selling it, making the combination with storage batteries a viable option.
👉 For purchase prices, periods, etc., visit the Agency for Natural Resources and Energy
Benefit 2: You can utilize subsidies!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the conditions, you may be able to utilize subsidies!
Reducing the actual burden amount through subsidies is a significant advantage!
In the case of Chiyoda Ward, in addition to national and Tokyo metropolitan systems, there may be eligibility for the Chiyoda Ward Energy Conservation Renovation Subsidy Program (solar power generation systems and storage systems) (the ward’s subsidy requires application before construction, and the budget for the 2026 fiscal year has already reached its limit and is temporarily closed for applications).
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.
Solar panels themselves do not produce noise or exhaust gases during the generation process, making them an environmentally friendly method of power generation. (However, devices like power conditioners may have operational noise.)
Advantage 4 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 heat shielding effects can be 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 functionality, 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 “three points to note” when installing solar panels!
Point 1 Maintenance costs are incurred
One maintenance cost that is particularly easy to overlook is the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reattaching the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to ask for a simulation that also considers maintenance costs before introducing solar panels!
Point 2 The risk of leaks increases depending on the roofing material
The method of securing slate roofs and tile roofs varies depending on the construction method, but when using screws or other fasteners to secure the roofing material and substrate, waterproofing treatment 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 treatment, but if you are concerned about making holes, one option is to replace the roofing material itself with a metal roof and secure the solar panels using the catch method. (The catch method has compatibility conditions between the roofing material and the fasteners, and it cannot be used with all metal roofs.)
Catch-type base fasteners for horizontal metal roofs
Note 3: The roof will become heavier
To install solar panels, 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.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
Choosing Method 1: Compare by Total Output of the Roof
When installing solar panels on the roof, it is important to consider how much power can be generated in a limited area, and the more power generated, the better!
Solar panels come in various sizes depending on the manufacturer, and their outputs also differ.
For example, a 350W output panel and a 400W output panel may seem 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,” 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 a single panel is lower, the total output of the roof may be higher!
It is important to consider the total output of the roof rather than the output of a single panel!
*The above calculations are for total output (kW). The actual power generation (kWh) will vary depending on conditions such as the roof’s orientation, slope, and shading.
Choosing Method 2: Compare by Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases over 10 and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output warranty values are standard figures for guarantees and do not indicate the actual degradation rate or power generation amount.
Choosing solar panels while considering both initial output and degradation rates 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 differ by manufacturer.
Some manufacturers offer a 30-year warranty for output, while others provide a 10-year warranty, so it varies widely!
A longer warranty is always better, so be sure to check the warranty period and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Chiyoda Ward
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Chiyoda Ward. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Chiyoda 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 published 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 Chiyoda 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) will be eligible from pre-applications made after October 1, 2026. The energy-saving renovation subsidy program in Chiyoda Ward (20% of eligible expenses for solar and storage systems, with a maximum of 1 million yen) has reached its budget for Reiwa 8 and is temporarily closed for applications. 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?
For many programs, procedures must be completed before construction. Tokyo’s subsidies require pre-application before installation, and if you proceed with installation first, you will be ineligible. Chiyoda Ward’s grants also require application and notification of approval before construction, and starting work beforehand will make you ineligible. 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 it varies depending on the construction method, and when securing hardware to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten Co., Ltd. is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation and suggest methods such as roof overlay (cover method) or replacement 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 on how to proceed with the installation 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 just the storage battery. You can compare “solar panels only” and “solar panels + storage battery” through a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing roofs or roofs with shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten Co., Ltd., we create a layout diagram from the drawings and on-site survey, and provide you with the installation capacity and power generation simulation.
Even in the urban area of Chiyoda Ward, the way shadows are cast by surrounding buildings varies from house to house. You can check the estimated power generation through the power generation simulation.
How long will the construction period be?
In 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 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 electricity?
For residential use (less than 10 kW), from the certification 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 price will apply for the 2026 fiscal year.
The idea is to recover initial costs more quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten Co., Ltd. provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten Co., Ltd. sends out annual after-maintenance DM notices and visits customers who wish for inspections. We can also clean solar panels using a special brush if the power generation is reduced due to dirt.
The roof is a place that is difficult to check by yourself, so if you have any concerns, please feel free to consult us.
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 removal and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Chiyoda City, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including roof work and exterior wall work, in Chiyoda City, Tokyo, including solar panel installations.
We receive many requests from 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 great feedback from many customers.
We continue to update our construction performance records every year, and we will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and re-roofing but also partial roof repairs, exterior painting, and exterior wall cover methods.
We are also happy to handle small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide emergency measures without setting up scaffolding, as long as safety can be ensured, so please consult us!
“I want to know about recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide optimal solutions for specific requests.
We will never propose unnecessary work focused on profit!
We always stand in the customer’s position and propose the best construction plan!
We are confident that we will not be outdone by other companies in terms of cost, quality, and organization for exterior work!
We are confident, so we welcome competitive quotes!
Estimates are completely free, and if our company is found to be inferior to others, you are free to decline!
Characteristics of Chiyoda City, Tokyo and Points for Solar Work
Chiyoda Ward, located in the center of Tokyo, is an area that spreads around the Imperial Palace, featuring business districts such as Otemachi and Marunouchi, as well as neighborhoods like Akihabara, Kanda, and Jimbocho. The official page of Chiyoda Ward provides hazard maps for floods (Kanda River version and Arakawa version), storm surges, and landslide disasters.
We have summarized points to consider when installing solar panels and storage batteries in Chiyoda Ward’s residential environment below. (Tap to open)
View the characteristics of Chiyoda Ward, Tokyo, and points for solar construction
■ Check the installation locations of storage batteries and power conditioners against the hazard map assumptions
Chiyoda Ward’s hazard map allows you to confirm assumptions for floods targeting the Kanda River, Nihonbashi River, and Sumida River, as well as floods due to the breach of the Arakawa levee, storm surges, and landslide disasters. When deciding on the installation locations for storage batteries and power conditioners, it is reassuring to check the flood assumptions for your residence on the hazard map and consider the height and position of the installation.
■ Tokyo’s annual sunshine hours are approximately 1,927 hours
The Japan Meteorological Agency’s average values (1991-2020) indicate that Tokyo’s annual sunshine hours are approximately 1,927 hours.
Since power generation varies by season, it is important to conduct annual power generation simulations and select the capacity of storage batteries to match the times when electricity is used the most.
■ In areas with nearby buildings or mid-rise structures, check for shadows from surrounding buildings
In business districts or areas with closely built mid-rise structures, the shadows cast by surrounding buildings vary for each house depending on the orientation and height of the roof or rooftop. Since solar panels generate less power when shaded, Kakeru Koumuten creates layout diagrams based on blueprints and the actual site conditions, allowing you to confirm through power generation simulations.
■ Not only single-family homes but also condominiums are eligible for the ward’s subsidies
Chiyoda Ward’s energy-saving renovation subsidy program includes not only single-family homes but also condominiums. Installing on the rooftops of condominiums may require the agreement of the management association and confirmation of ownership relations, so please consult us in advance.
■ In areas with narrow front roads, plan scaffolding and equipment delivery carefully
In places with narrow front roads or where surrounding buildings are close, careful planning for scaffolding and equipment delivery may be necessary. Kakeru Koumuten will respond to the site conditions with our own scaffolding team and scaffolding materials.
■ Check the roof condition according to the building’s age
For buildings that have been around 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 Chiyoda Ward
Tokyo’s subsidies require pre-application to Cool Net Tokyo before installation. Chiyoda Ward’s energy-saving renovation subsidy program also requires application and notification of approval before construction. It is essential to check the procedures and timelines for each program in advance, in line with the timing of the construction.
Our company serves Kanagawa Prefecture and Tokyo, and we handle many exterior construction and solar power projects in Chiyoda 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 Chiyoda Ward, Tokyo
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Chiyoda Ward, Tokyo
Iidabashi, Chiyoda Ward / Ichibancho, Chiyoda Ward / Iwamotocho, Chiyoda Ward / Uchikanda, Chiyoda Ward / Uchisaiwaicho, Chiyoda Ward / Otemachi, Chiyoda Ward / Kajicho, Chiyoda Ward / Kasumigaseki, Chiyoda Ward / Kanda Aioicho, Chiyoda Ward / Kanda Awajicho, Chiyoda Ward / Kanda Izumicho, Chiyoda Ward / Kanda Iwamotocho, Chiyoda Ward / Kanda Ogawacho, Chiyoda Ward / Kanda Kajicho, Chiyoda Ward / Kanda Kitano Moromachi, Chiyoda Ward / Kanda Konyacho, Chiyoda Ward / Kanda Sakumakawagashi, Chiyoda Ward / Kanda Sakumacho, Chiyoda Ward / Kanda Sarugakucho, Chiyoda Ward / Kanda Jinbocho, Chiyoda Ward / Kanda Sudacho, Chiyoda Ward / Kanda Surugadai, Chiyoda Ward / Kanda Tamacho, Chiyoda Ward / Kanda Tsukasaicho, Chiyoda Ward / Kanda Toyamacho, Chiyoda Ward / Kanda Nishifukudacho, Chiyoda Ward / Kanda Nerenbai, Chiyoda Ward / Kanda Hanaokacho, Chiyoda Ward / Kanda Higashikonyacho, Chiyoda Ward / Kanda Higashimatsushitacho, Chiyoda Ward / Kanda Hirakawacho, Chiyoda Ward / Kanda Matsunagacho, Chiyoda Ward / Kanda Mikuracho, Chiyoda Ward / Kanda Misakicho, Chiyoda Ward / Kanda Midoricho, Chiyoda Ward / Kioicho, Chiyoda Ward / Kitano Marukoen, Chiyoda Ward / Kudan Minami, Chiyoda Ward / Kudan Kita, Chiyoda Ward / Imperial Palace Outer Garden, Chiyoda Ward / Kojimachi, Chiyoda Ward / Gobancho, Chiyoda Ward / Sanbancho, Chiyoda Ward / Sotokanda, Chiyoda Ward / Chiyoda, Chiyoda Ward / Nagatacho, Chiyoda Ward / Nishikanda, Chiyoda Ward / Nibancho, Chiyoda Ward / Hayabusaicho, Chiyoda Ward / Higashikanda, Chiyoda Ward / Hitotsubashi, Chiyoda Ward / Hibiya Park, Chiyoda Ward / Hirakawacho, Chiyoda Ward / Fujimi, Chiyoda Ward / Marunouchi, Chiyoda Ward / Yurakucho, Chiyoda Ward / Yobanchō, Chiyoda Ward / Rokubancho, Chiyoda Ward
・Trust Kakeru Koumuten for exterior wall painting in Chiyoda, Tokyo!
・Trust Kakeru Koumuten for roof renovations in Chiyoda, Tokyo!
・Trust Kakeru Koumuten for exterior renovations in Chiyoda, Tokyo!
・Kakeru Koumuten Co., Ltd. project achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. service menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・Explaining the importance of comparison estimates and key points!
・Top 12 solar power generation manufacturers! Features and selection tips included!
・What are the installation costs for solar power generation? Tips to reduce costs thoroughly explained!
・What are the best locations for solar power installation? Key points for site selection included!
・Find out about solar power generation estimates here!
We welcome inquiries via LINE as well◎
We are also updating our Instagram regularly◎ Please follow us◎
contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
