Leave Your Solar Panel Installation Work in Kamakura City, Kanagawa Prefecture to Kakeru Koumuten Co., Ltd.!
For solar panel and battery installation in
Kamakura City, Kanagawa Prefecture,
trust Kakeru Koumuten!
Kakeru Koumuten is a specialized exterior renovation company based in Aoba Ward, Yokohama City.
As a company strong in roofing work, we are entrusted with solar panel and battery installation considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Kamakura City”
“Costs for Solar Panel and Battery Installation”
“Subsidies Available for Solar System Installation in Kamakura City”
We will also explain the above three points!
Installing solar panels carries risks such as “the occurrence of leaks” and other troubles.
To ensure a satisfactory solar panel installation, we recommend obtaining three estimates!
Table of Contents (tap to open/close)
- Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Kamakura City, Kanagawa Prefecture
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Kamakura City
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installation Contractor in Kamakura City, Kanagawa Prefecture
- 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 Kamakura City
- If You’re Looking for a Solar Panel Installation Contractor in Kamakura City, Contact Kakeru Koumuten
- Characteristics of Kamakura City, Kanagawa Prefecture and Points for Solar Installation
- Service Area in Kamakura City, Kanagawa Prefecture
Reasons Kakeru Koumuten is Chosen for Solar Panel Installation in Kamakura City, Kanagawa Prefecture
The reasons why we are entrusted with solar panel installation by customers in Kamakura City, Kanagawa Prefecture include
one reason being that Kakeru Koumuten has a base in Kanagawa Prefecture,
and our unique strengths in solar panel installation that cannot be imitated by other companies
which have received high praise from many customers.
so we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Can 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 prepared 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 according to construction conditions and can assemble scaffolding in-house.
By not outsourcing scaffolding work and using our own scaffolding team, we can also cut costs for scaffolding work.
We own scaffolding materials for approximately 50 houses!
In the residential areas of Kamakura City, surrounded by mountain ridges and with houses lined up in valleys called “yatoh,” our in-house scaffolding team plans scaffolding according to the local conditions.
Storage of Materials in Our Large Warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, you can purchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we can respond quickly in emergencies!
In-house sorting and transportation of waste materials
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior renovation dedicated showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are attached to the roofing materials!
You can also simulate the 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 explain the structure, allowing for detailed explanations!
3.All work performed by our own team
One of Kakeru Koumuten’s major strengths is complete in-house construction.
By having Kakeru Koumuten handle everything from inquiries to project completion in a consistent manner, we can keep costs down 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 perform consistent in-house construction from temporary scaffolding installation, exterior wall painting, to roof renovations!
4. Various Permits and Skilled Workers
We have obtained construction industry permits and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal and painting technicians, and we are confident in our construction techniques.
We can also handle large-scale roofing projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation, our own construction warranty (leak warranty) is also included!
(The construction warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless a roof renovation is performed. The construction warranty is separate from the manufacturer’s product warranty, and the coverage and conditions vary based on the warranty details.)
Aftercare is available every year, and we send out annual notification DM.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roofing troubles and situations.
Even if you cannot access the roof at high altitudes, we can utilize a drone 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 or other factors, we can provide cleaning services using a specialized brush.
We will respond according to your wishes.
7. Human Resource Development
To enhance 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.
Even customers who are not familiar with solar construction will receive materials that clearly summarize important points and disadvantages!
We encourage you to obtain comparative estimates and compare them with other companies’ plans!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 to 30 years.
Confirming whether it is safe to install them directly on the current roof is the key point to prevent leaks and unnecessary expenses before installation!
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 material, such as slate, tiles, metal roofs, and flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest a roof renovation first. |
| 2. Condition of the Substrate and Waterproof Sheet | If the sheathing or roofing (waterproof sheet) under the roofing material is damaged, it will affect the fixing strength of the fittings and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, will affect the power generation. We will create a layout diagram from the drawings and the site, and you can confirm 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 overall output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will check whether the method involves drilling holes in the roofing material for fixing or using fittings to secure the roofing material. The fixing method varies by technique, so please 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. After investigating the existing roof, substrate, and load capacity, switching to lightweight roofing materials may also be an option if necessary. |
| 7. Location of Equipment Installation 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. |
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 fixing parts, cracks or deterioration of slate, condition of the substrate. If deterioration is significant, consider roof overlay or replacement first. |
| Tile Roof | Fixed with brackets and methods suitable for the type of tile (even methods that do not drill holes in the tiles will secure to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the 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 renovate the roof 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 is strong in roofing work and can also handle the removal and reinstallation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Kamakura City, Kanagawa Prefecture
PossibleSubsidies and Grants in Kamakura City, Kanagawa Prefecture
When introducing solar panels and storage batteries in Kamakura City, there is a possibility of being eligible for programs from “the national government,” “Kanagawa Prefecture,” and “Kamakura City.”
The following information is based on the official pages of each program as of October 6, 2026. The application status may change depending on the budget and application period, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Kamakura City “Reiwa 8 Year Residential Renewable Energy and Energy-Saving Equipment Installation Subsidy” | Installed in a residence where the applicant resides and owns/uses the equipment (no delinquency on city taxes, unused items). Solar power generation must be certified under the FIT system. Storage batteries must be stationary lithium-ion storage systems, and applications can be made for storage batteries alone. Application must be submitted before starting installation work. | Solar: 10,000 yen per kW (maximum 50,000 yen) Storage Battery: Maximum 50,000 yen V2H: Maximum 30,000 yen, Enefarm: Maximum 40,000 yen, ZEH Add-on: 50,000 yen (conditions apply) |
Applications accepted from April 1, 2026 (budget of 6 million yen, execution rate as of September 30, 2026, is approximately 72%. Until the budget is reached) Application deadline is March 1, 2027, and performance report is due by March 31, 2027. |
| Kamakura City “Accelerated Measures Subsidy for Households” | Solar power generation that self-consumes more than 30% of the electricity generated without certification under FIT or FIP. Storage batteries can only be installed simultaneously with solar power. Cannot be combined with the city’s residential renewable energy subsidy. | Solar: 70,000 yen/kW Storage Battery: One-third of the cost (maximum 141,000 yen/kWh) |
The household program reached its budget with applications on June 17, 2026, and is now closed (currently not accepting applications). |
| Kanagawa Prefecture “Reiwa 8 Year Kanagawa Prefecture Residential Solar Power and Storage Battery Installation Subsidy” | For single-family homes or apartment buildings in the prefecture, solar power and storage batteries must be installed together in earthquake-resistant homes. Applications must be made by the individual, and construction can begin after the grant decision. | Solar: 70,000 yen/kW Storage Battery: 150,000 yen per unit |
Phase 1: May 11, 2026 – June 30, 2026 Phase 2: September 7, 2026 – September 30, 2026 (first-come, first-served) Phase 2 has reached its application deadline. Please check the prefecture’s official page for future applications. |
| National “DR Home Storage Battery Project” (Reiwa 7 Year Supplement) | New installation of registered home storage systems that can be utilized for DR (demand response). | Calculated based on a standard amount of 34,500 yen per initial effective capacity of 1 kWh (subsidy rate within 3/10, maximum 600,000 yen per application). | Reached its budget on May 29, 2026, and public recruitment has ended (currently not accepting applications). |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Storage batteries are one of the eligible facilities, but must be combined with essential works such as insulation renovation of windows (openings) and the structure; applications cannot be made for storage battery installation alone. Solar panels are not included as eligible facilities. | Storage Battery: 96,000 yen per unit | Budget will end once the limit is reached. Please check the official website for the application status. |
| Kanagawa Prefecture “Reiwa 8 Year Kanagawa Prefecture Self-Consumption Renewable Energy Introduction Subsidy” | Corporations and individual business operators filing blue returns (individual residences are not eligible). Solar power must have a generation output of 10kW or more, facilities for business use, equipment not certified under FIT/FIP, etc. | Solar power: 80,000 JPY/kW, etc. Storage system: 50,000 JPY/kWh (maximum 5 million JPY) |
Application will close on September 3, 2026 (when the application amount reaches the budget amount) |
For Kamakura City’s residential subsidies, application is required before starting installation work, and for Kanagawa Prefecture’s residential subsidies, construction must begin after receiving “grant decision”. If construction starts beforehand, it will be ineligible. Additionally, the two subsidies from Kamakura City (subsidy for installation of renewable energy and energy-saving equipment and subsidy for accelerated priority measures) cannot be combined. The eligibility for combining city and prefectural subsidies must be checked for each system. It is not guaranteed that applying will result in a grant, so please confirm before contracting or starting work.
At Kakeru Koumuten, we will guide you on eligibility conditions and business requirements for each system after confirming them.
Kamakura City “Reiwa 8 Year Residential Renewable Energy and Energy-Saving Equipment Installation Subsidy”
Kamakura City provides subsidies for those installing solar power generation systems and storage batteries in residential properties within the city. Eligible applicants are those who install equipment in their own residences within the city, own and use it, and have no delinquency in city taxes, among other conditions.
The subsidy amount is 10,000 JPY per 1kW of the total nominal maximum output for solar power (maximum 50,000 JPY), and a maximum of 50,000 JPY for storage batteries. Solar power must be certified under the FIT system, and applications for storage batteries can be made even if not installed simultaneously with solar power. Additionally, there are add-ons for V2H (maximum 30,000 JPY), EneFarm (maximum 40,000 JPY), and ZEH, etc. (50,000 JPY).
The budget is 6 million JPY, and as of September 30, 2026, the execution rate is approximately 72%. Applications will close once the budget is reached, so those considering applying should check early. Applications must be made before starting installation work, and grant applications are accepted until March 1, 2027.
👉 Click here for the official Kamakura City page
Kamakura City “Accelerated Priority Measures Subsidy for Business Expenses” (Solar Power Generation Equipment and Storage Batteries)
Kamakura City also offers subsidies for solar power generation that does not receive FIT/FIP certification and for storage batteries installed simultaneously with solar power for self-consumption. For households, the subsidy is 70,000 JPY per 1kW for solar power and one-third of the cost for storage batteries (maximum 141,000 JPY/kWh).
However, the household applications reached the budget on June 17, 2026, and applications have closed. Applications for business use by small and medium-sized enterprises are still being accepted, but the execution rate of the budget is approximately 97% (as of October 2, 2026). Those considering applying for business use should check the latest status on the city’s official page.
👉 Click here for the official Kamakura City page
National Subsidy “DR Home Battery Project (Support Project for Home Storage Systems for DR Resource Introduction)”
The government has been implementing the “DR Home Battery Project” to support the installation of home storage batteries.
This program targets individuals who are newly introducing registered storage systems that can be utilized for demand response (DR). In the fiscal year 2025 supplementary budget, the subsidy amount is determined based on a standard amount of 34,500 JPY per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum of 600,000 JPY per application. There are conditions such as that contracts or orders made before the grant decision are not eligible.
However, the fiscal year 2025 supplementary budget application amount reached the budget 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). Applications are currently not accepted, so please check the official website for future public recruitment.
Additionally, there are currently no subsidies confirmed for the installation of solar panels on existing homes.
👉 Click here for the official DR Home Battery Project website
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Housing Solar Power Generation and Storage Battery Installation Subsidy”
In Kanagawa Prefecture, subsidies are provided for those who install both “solar panels” and “storage batteries” in their homes.
The subsidy details are 70,000 JPY per kW of solar power generation output and 150,000 JPY per storage system.
For example, if you install a 4 kW solar panel and one storage battery, the subsidy amount calculation would be 4 kW × 70,000 JPY + 150,000 JPY = 430,000 JPY.
The storage system must be a registered product, if construction begins before the grant decision, it will not be eligible, and the application must be made by the individual (proxy applications by contractors are not allowed). The target homes must also ensure seismic performance. The eligibility for combining with other subsidy programs may vary by program, so please be sure to check.
In fiscal year 2026, the first phase (May 11 to June 30) and the second phase (September 7 to September 30, first-come-first-served) were accepted, and the second phase has reached its application deadline. For future recruitment, please check the official page of Kanagawa Prefecture.
👉 Click here for the official Kanagawa Prefecture page
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Self-Consumption Type Renewable Energy Installation Subsidy” (for businesses)
Kanagawa Prefecture is also implementing subsidies for businesses that install “self-consumption type” facilities that use electricity generated from solar panels.
The target is corporations or individual business owners who file blue tax returns, and the introduction to individual residences is not eligible.
Solar power generation must have a generation output of 10kW or more, supply electricity to business facilities within the prefecture, and not be equipment certified under FIT or FIP, among other conditions.
The subsidy amount is 80,000 yen per kW for solar power generation and 50,000 yen per kWh for the accompanying storage system (with a maximum of 5 million yen), among other details.
As the application amount reached the budget amount for Reiwa 8, the recruitment was closed on September 3, 2026.
For businesses considering the installation of solar panels on commercial buildings in Kamakura City, please check the official page of Kanagawa Prefecture for the next recruitment.
👉 Click here for details
Solar Panel Installation & Storage Battery Installation Price List
⇧Service Menu | Click here for costs related to solar panel removal and water heater removal
Breakdown of Installation Capacity, Equipment, and Construction Costs
It is important to check the costs of solar panels and storage batteries by separating them into “equipment costs (device costs)” and “construction costs.”
Even for the same “solar panel installation set,” the amount can vary significantly depending on the installation capacity, the grade of the equipment, and the condition of the roof.
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 in terms of the amount of electricity they can store, represented 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 as approximately 800,000 JPY to 1,200,000 JPY for 3-5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6-10 kW. (These are just approximate amounts and may vary based on wiring length, scaffold range, existing roofing materials, panel layout, etc.)
▶ For installation menu and costs for solar panel and storage battery installation, click here
Items to Check in the Quotation (Cost Confirmation)
When comparing prices in competitive quotations, it is common to compare different capacities and equipment. Please check if the following items are clearly stated in each company’s quotation!
| 1. Solar Panels | Manufacturer, model number, output of one panel (W), number of panels, total installation capacity (kW) are written. |
| 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 storage battery. |
| 3. Storage Battery | Manufacturer, model number, capacity (kWh), range usable during a power outage (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of the hardware suitable for the roofing material and the method of securing it (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 for fixed parts, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | Extent of support for applications to the power company, certification applications for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Range and quantity of scaffolding. If it is simultaneous with roof work or exterior painting, check that the same range 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 it is tax-inclusive or tax-excluded, conditions under which additional costs may arise, and details and duration of manufacturer and workmanship warranties. |
If the capacity differs, both the price and the power generation will change. Kakeru Koumuten Co., Ltd. warmly welcomes comparative estimates, so if you bring estimates from other companies, we will explain the differences for each item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can obtain a rough estimate and a profit simulation for up to 30 years!
If you know the total installation capacity of the solar panels on the roof and the capacity of the storage 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, selling prices, and costs for equipment inspection or replacement.
Customer Voices
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customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
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customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
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customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
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customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
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customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
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customer reviews
Higashiyamato City, Tokyo | We received reviews about exterior painting and roof overlay (cover method)!
Examples of Solar Panel Installation
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh |
| Base Mounting Hardware Used |
| Niigata Manufacturing / Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Arrangement |
| Fixed by catching the horizontal metal roof with catch type hardware (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the grant being provided, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant amount and recovery estimate are based on the system and calculations at the time of construction, and may differ under the current system. |
| Construction Period |
| Approximately 3 days |
| Completion Month |
| April 2025 |
| Inquiry Details |
| I am considering the installation of solar panels and storage batteries. I heard that grants are available, and I would like to know how much can be provided. |
Our Proposal
We visited to provide 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 understood the expected amount of grants that will be provided, and we explained this to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Kamakura City, Kanagawa Prefecture
There are many solar panel installation contractors available in Kamakura City, Kanagawa Prefecture, and you may be unsure which contractor to choose.
Therefore,when requesting solar panel installation or battery storage installation work, let’s check the following 4 points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the presence of warranties and aftercare maintenance
● Obtain estimates from multiple contractors (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 can sometimes be caused by a lack of knowledge and verification regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient verification of roofs and waterproofing
・Solar panels were installed on a severely deteriorated roof, leading to leaks
・Solar panels were installed on a roof with a short lifespan, necessitating a renovation for removal and reinstallation within a few years
・Misjudgment of the type of waterproofing led to incorrect processing, 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 Verification Before Installing Solar Panels” in this article
Confirm the presence of warranties and aftercare maintenance
When choosing a solar installation contractor, let’s confirm the presence 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 solar panels and battery storage units come with manufacturer warranties, it is also important to check for the presence of a workmanship warranty in case leaks occur after installation!
For contractors that offer workmanship warranties, if leaks occur after installation, they may be able to respond under the warranty, provided it is within the warranty period and conditions.
Additionally, some contractors offer after-service separate from the warranty, so be sure to check if the contractor you are considering has after-service.
Changes or damage on the roof may be in areas that are not visible, so there is a possibility that customers may not notice them.
By conducting inspections in after-maintenance, you can easily prevent major repairs or breakdowns by discovering abnormalities early!
Kakeru Koumuten Co., Ltd. provides a rain 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-maintenance and send out DM every year!
After checking the DM, if you wish, we will visit for after-maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, be sure to obtain estimates from multiple contractors.
Even for the same manufacturer and the same construction content, costs may vary, as well as warranties and after-services.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request from your desired contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates,
“Check the items in the estimate”
“Type of solar panel”
“Warranties and after-services”
and make detailed comparisons to make a judgment! If the rank of auxiliary materials is low or if processes are skipped, costs can be reduced, so avoid judging solely based 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.
For systems like the Kanagawa Prefecture housing subsidy, where applications cannot be delegated to contractors and must be submitted by the individual, 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 the prefectural housing subsidy, this means obtaining a grant decision) before proceeding with the construction!
For the prefectural housing subsidy, after the construction is completed, a performance report must be submitted, and the flow will be to undergo a review before the subsidy is granted! (The flow of procedures varies by system)
▶ Go to “Subsidies and Grants That May Be Applicable in Kamakura City” in this article
Benefits of Introducing Solar Power Systems
The benefits of introducing solar panels are summarized in the following 5 points!
Benefit 1: Economic Benefits
The biggest benefit of introducing solar panels is the economic advantage!
While the selling price of electricity has decreased compared to 10 years ago, you can gain benefits by reducing the amount of electricity you buy from the utility company by consuming the electricity you generate!
As electricity prices rise, the ability to cover your consumption with solar power becomes increasingly attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
For residential use (under 10kW), the selling price (FIT) from certifications after October 2025 is set at “24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year.” The same price will apply for the 2026 fiscal year. After the 5th year, it is often more advantageous to use it at home (self-consumption), making the combination with a storage battery a viable option.
👉 For purchase prices and periods, click here
Benefit 2: You Can Utilize Subsidies!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the requirements, you may be able to utilize subsidies!
Reducing the actual burden through subsidies is a significant advantage!
In the case of Kamakura City, there may be subsidies available from the city or Kanagawa Prefecture, so please check the latest application status.
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 do have operational noise.)
Benefit 4: Heat Insulation Effects Can Be Expected!!
By installing them on the roof or rooftop, the panels block direct sunlight to the roof.
Especially in summer, it can help reduce the temperature rise of the roof, providing expected heat insulation effects!
(Note that 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.
(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
A particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reinstalling the solar panels.
If the existing roof is deteriorated, it is reassuring to renovate it with durable roofing materials before installing 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 is reassuring to consider maintenance costs in simulations before introducing solar panels!
Point 2 The risk of leaks increases depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but in methods that fix hardware to the roofing material or substrate with screws, waterproofing of the fixed parts is crucial.
In methods that 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 it 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 capacity, switching to a lighter roof may be one 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 based on the total output of the roof
When installing solar panels on the roof, it is important to know how much power can be generated in a limited area, and it is always better to generate more power!
The size and output of solar panels vary by manufacturer.
For example, a 350W output panel and a 400W output panel may seem that the higher output panel is better at first glance.
However, if the size of the panel does not fit well with the roof, there may be cases where “20 panels of 350W can be installed” and “15 panels of 400W can be installed,” leading to different numbers of panels that can be installed on the same roof due to size differences.
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 the calculation of total output (kW). The actual power generation amount (kWh) will vary depending on conditions such as the roof’s orientation, slope, and shading.
Choosing Method 2: Compare based on the degradation rate of solar panels
Solar panels have a degradation rate, and their output gradually decreases over 10 years and 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 amount.
By considering the degradation rate as well as the initial output, you can choose solar panels without regret!
Choosing Method 3: Compare based on warranty years
Solar panel warranties include various types such as “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty years vary by manufacturer.
Regarding output warranties, some manufacturers offer a 30-year warranty while others offer a 10-year warranty, so they vary!
A longer warranty is always better, so be sure to check the warranty years and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Kamakura City
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Kamakura City. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Kamakura City, Kanagawa Prefecture?
The cost varies depending on the installation capacity, equipment, and roof condition. In the above case study (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
Guidelines for costs by capacity are published on the solar panel 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 Kamakura City?
As of October 6, 2026, Kamakura City’s “Subsidy for Installation Costs of Residential Renewable Energy and Energy-Saving Equipment” (10,000 yen per kW of solar power, up to 50,000 yen; storage battery up to 50,000 yen) will continue to accept applications until the budget is reached, with an execution rate of about 72% as of September 30, 2026. On the other hand, the city’s priority measures acceleration project subsidy for households has ended. The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power; 150,000 yen per unit for storage batteries) is approaching the application deadline for the second term of fiscal year 2026, and the national DR household storage battery project has concluded its public recruitment.
Application status may change, so please refer to the subsidies and grants section and consult with us before signing a contract.
Can I apply for subsidies even after the construction is completed?
For many programs, procedures are required before construction. The application for Kamakura City’s residential subsidy must be made “before starting the installation work,” and the Kanagawa Prefecture subsidy requires “starting construction after the grant decision,” meaning that if you install first, you will be ineligible.
The order of procedures varies by program, so please confirm before signing a contract or starting construction.
Can solar panels be installed on a slate roof? I’m worried about leaks.
Installation is possible on a slate roof, but it is necessary to check the condition of the roofing material and substrate. The method of securing the panels varies by technique, and in methods that secure brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is crucial.
Kakeru Koumuten is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation and suggest methods such as roof overlay (cover method) or replacement if deterioration is advanced.
The roof is old. Should I do a roof renovation first?
It depends on the condition of the roof. If a roof renovation is needed after 10 to 20 years of installation, the cost for removing and reattaching solar panels will be incurred separately. 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 on how to proceed with the installation after confirming the condition of the roof through a site survey!
Is it better to install a storage battery together with solar panels?
For those who want to use generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price of electricity will be 8.3 yen/kWh after the fifth year, making it more advantageous to use it at home rather than sell it.
Additionally, Kanagawa Prefecture’s subsidy requires the simultaneous introduction of solar panels and storage batteries, while Kamakura City’s residential subsidy can be applied for with just the storage battery (up to 50,000 yen). 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, we create a layout diagram from the drawings and site survey, and provide you with the installation capacity and power generation simulation.
Kamakura City is surrounded by mountains on three sides, and many houses are built nestled among the greenery of the mountains, resulting in different shadow patterns from surrounding mountains and trees for each house. You can check the expected power generation through the power generation simulation.
How long does the construction period take?
In the above construction example (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roof work is done simultaneously or depending on the shape and installation capacity of the roof.
Please note that additional time is required for applications for subsidies and power companies, so please consult us early.
What is the current selling price (FIT)?
For residential use (under 10 kW), the selling price from certifications after October 2025 will be 24 yen/kWh for the first 4 years, and 8.3 yen/kWh from the 5th to the 10th year, and the same price will apply for the 2026 fiscal year.
The idea is to recover initial costs quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-maintenance DM notifications and visits customers who wish to have inspections. We can also clean solar panels using a special brush if the power generation decreases due to dirt.
Since it is difficult to check areas on the roof by yourself, please feel free to consult us if you have any concerns.
Can you also handle renovations for roofs that already have solar panels installed?
Yes, we can. Kakeru Koumuten can remove 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 warehouse.
For information on costs, please see the solar panel removal and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Kamakura City, please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roof work, and exterior wall work in Kamakura City, Kanagawa Prefecture.
We receive requests from many clients, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received great feedback from numerous customers.
We continue to update our construction achievements every year, and we will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, including roof overlay work, roof replacement work, partial roof repairs, exterior painting, and exterior cover methods, all by our own team.
We are also happy to assist with small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide temporary measures without setting up scaffolding, as long as safety can be ensured, so please consult with us!
“I want to know about recommended solar panels”, “I want to keep costs as low as possible”, “I just want an estimate for now”, we will provide optimal solutions for your specific requests.
We will never propose unnecessary work that prioritizes profit!
We always stand in the customer’s shoes and will 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!
Features of Kamakura City, Kanagawa Prefecture, and Points for Solar Work
Kamakura City is surrounded by mountains on three sides, with the ocean spreading to the south. Houses are lined up in valleys called “yato,” and the entire city is designated as a landscape planning area.
We have summarized the topography and landscape rules of Kamakura City and points to be careful of when installing solar panels and storage batteries below. (Tap to open)
View the features of Kamakura City and points for solar work
■ A topography surrounded by mountains. It is important to check shadows and roof orientations for houses in the valleys.
Kamakura City Historical Landscape Maintenance and Improvement Plan (Official City Document) states that most of Kamakura City is occupied by mountain ridges and plateaus, with few flat areas. About Yato (Official City Document) describes that valleys cut into the mountains are called “Yato,” and currently, houses are lined up deep within these valleys.
In residences surrounded by mountains, the shadows cast by the mountains and trees vary from house to house. At Kakeru Koumuten Co., Ltd., we create layout diagrams based on blueprints and the actual site conditions, allowing you to confirm through a power generation simulation.
■ The entire city is a landscape planning area. Consideration for panel color and installation position is necessary.
Considerations for Landscape When Installing Solar Power Systems in Kamakura City (Official City Document) states that the entire city of Kamakura is a landscape planning area, and consideration for the landscape is required during installation. It is recommended to choose products that match the color of the roof, products that are dark and have low gloss and reflection, products that are thin and appear integrated with the roof, avoid frames with strong gloss, and position them in locations that are not prominent from the street.
The type and arrangement of panels should be selected while balancing power generation and landscape considerations. Please consult us during the estimation process.
■ About 55.5% of the city is designated as a scenic area. Pre-confirmation is required if exterior wall painting is to be done simultaneously.
Kamakura City Scenic Area Ordinance (Official City Document) designates approximately 2,194 hectares (about 55.5% of the city) as scenic areas, and within these areas, permission from the mayor is required for new construction, expansion, or changes to the color of exterior walls. If you plan to paint the exterior walls along with solar panel installation, it is important to confirm whether your residence falls within a scenic area beforehand. Depending on the scale and method of installation, procedures may also be required, so please check according to the city’s guidance.
■ Oceanic climate. Confirm installation conditions for homes near the sea.
The city’s historical landscape maintenance and improvement plan states that Kamakura City is influenced by the oceanic climate of Sagami Bay to the south. In areas close to the sea, the installation conditions for salt damage areas set by manufacturers vary by model, so please confirm the installation location and model conditions during the estimation process. Waterproofing for the roof will also be thoroughly conducted, considering the rainy season.
■ Annual sunlight hours are approximately 2,000 hours.
City Current Situation Report (Official City Document) states that Kamakura City has approximately 2,000 hours of sunlight per year, making it suitable for solar power generation. The average temperature is 16.4℃, and the annual precipitation is 1,372.0mm.
Power generation varies with the seasons and roof conditions, so conducting a year-round power generation simulation and selecting battery capacity to match peak electricity usage times are key points.
■ Check the roof condition according to the age of the building.
According to the same data, approximately 58% of residential buildings in the city are single-family homes, about 67% are wooden houses, and around 33% were built before 1980 (Showa 55). For homes that have aged, it is important to check the condition of the roofing materials and substrate before installing solar panels. Depending on the state of the roof, installing them simultaneously with roof renovations can help reduce future costs for removing and reinstalling solar panels.
■ Roofs near green mountains require attention to fallen leaves and dirt
In homes close to green mountains, fallen leaves and dirt on the roof can affect power generation. Kakeru Koumuten Co., Ltd. can provide solar panel cleaning with specialized brushes, as well as rain gutter cleaning.
Our company is based in Kanagawa Prefecture and has undertaken many exterior construction and solar projects in Kamakura City.
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 Kamakura City, Kanagawa Prefecture
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Kamakura City, Kanagawa Prefecture
Inamuragasaki, Kamakura City / Imaizumi, Kamakura City / Imaizumidai, Kamakura City / Iwase, Kamakura City / Ueki, Kamakura City / Ougigaya, Kamakura City / Ofuna, Kamakura City / Omachi, Kamakura City / Okamoto, Kamakura City / Onarimachi, Kamakura City / Kajiwara, Kamakura City / Kamakurayama, Kamakura City / Kamiyacho, Kamakura City / Koshigoe, Kamakura City / Kobukurodani, Kamakura City / Komachi, Kamakura City / Gokurakuji, Kamakura City / Sakanoshita, Kamakura City / Sasame, Kamakura City / Zaimokuza, Kamakura City / Shichirigahama, Kamakura City / Shichirigahama Higashi, Kamakura City / Jomawari, Kamakura City / Juunisho, Kamakura City / Jyoumyouji, Kamakura City / Sekiya, Kamakura City / Takano, Kamakura City / Tamagawa, Kamakura City / Dai, Kamakura City / Tsu, Kamakura City / Tsu Nishi, Kamakura City / Tehiro, Kamakura City / Terabun, Kamakura City / Tokiwamachi, Kamakura City / Nikaido, Kamakura City / Nishikamakura, Kamakura City / Nishiomote, Kamakura City / Hase, Kamakura City / Fueda, Kamakura City / Yamazaki, Kamakura City / Yamanouchi, Kamakura City / Yuigahama, Kamakura City / Yukinoshita, Kamakura City
・For exterior wall painting in Kamakura City, Kanagawa Prefecture, trust Kakeru Koumuten Co., Ltd.!
・For roof renovations in Kamakura City, Kanagawa Prefecture, trust Kakeru Koumuten Co., Ltd.!
・For exterior renovations in Kamakura City, Kanagawa Prefecture, trust Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd. construction achievements
・Kakeru Koumuten Co., Ltd. aftercare services
・Kakeru Koumuten Co., Ltd. construction menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・Explaining the importance of comparative estimates and key points!
・Top 12 solar power generation manufacturers! Features and selection tips included!
・What are the installation costs for solar power generation? Comprehensive tips to reduce costs!
・What are the best locations for solar power installation? Key points for site selection included!
・For solar power generation estimates, click 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!
