Leave Your Solar Panel Installation Work in Isehara City, Kanagawa Prefecture to Kakeru Koumuten Co., Ltd.!
For
Solar Panel and Storage Battery Installation in
Isehara 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 storage battery installations that consider roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Isehara City”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Isehara 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 you have no regrets about your solar panel installation, we recommend obtaining three or so estimates!
Table of Contents (Tap to Open/Close)
- Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Isehara City, Kanagawa Prefecture
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Isehara 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 Isehara 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 Isehara City
- If You Are Looking for a Solar Panel Installation Contractor in Isehara City, Contact Kakeru Koumuten
- Characteristics of Isehara City, Kanagawa Prefecture and Key Points for Solar Construction
- Service Area in Isehara City, Kanagawa Prefecture
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Isehara City, Kanagawa Prefecture
The reasons why our company is entrusted with solar panel installation by customers in Isehara 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 multiple estimates!
1. We Can Also Handle Exterior Renovations Other Than 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 are cases where the roof and waterproofing at the installation site are outside of your expertise, so caution is necessary.
It is reassuring to have knowledge about the roof to avoid maintenance and problems 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 problems 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 solar work and exterior renovations at low cost and high quality.
We have established five bases centered in Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Ownership of Scaffolding Materials
To ensure safety during work on the roof, we own the necessary scaffolding materials for temporary scaffolding based on construction conditions, allowing us to set up scaffolding ourselves.
By conducting scaffolding work with our own scaffolding team instead of outsourcing, we can also reduce scaffolding construction costs.
We have scaffolding materials for approximately 50 single-family homes!
Even in the residential areas of Isehara City, where the terrain changes from hilly areas to plateaus and plains, our own scaffolding team will plan the scaffolding according to the site 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, we canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, enabling us torespond quickly in emergencies!
Sorting and transporting waste materials in-house
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior remodeling dedicated showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on the roofing materials!
Simulations for potential earnings and installation costs when introducing solar panels are also available!
Since roofing and exterior wall work often accompany each other, we also provide samples of roofing materials and models that explain the structure in detail!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is all work performed by our own team.
By having Kakeru Koumuten handle everything from inquiries to project completion in a consistent manner, we can keep costs down while providing high-quality roof remodeling.
Additionally, one representative will assist you from the estimate to project completion.
Since the same person handles sales and construction management, smooth communication is possible.
We can perform consistent in-house work from temporary scaffolding setup to exterior wall painting and roof remodeling!
4. Various Permits Obtained & Skilled Workers on Staff
We have obtained construction industry permits and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal and painting specialists on staff, 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, our solar panel installation work comes with our own workmanship warranty (leakage warranty)!
(The workmanship warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovation is performed. The workmanship warranty is separate from the manufacturer’s product warranty, and the coverage and conditions vary depending on the warranty details.)
Aftercare maintenance is available annually, and we send out notification DM every year.
If you have any questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
We are equipped to handle various roof troubles and situations.
If we cannot access the roof at height, we can utilize a drone for inspection!
During leakage investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of the solar panels decreases due to dirt, we can also perform cleaning using a specialized brush.
We will respond according to the customer’s wishes.
7. Human Resource Development
We create various roof models for skill improvement and conduct practical training.
Since the construction method varies depending on the shape and slope of the roof, we regularly provide technical training to ensure that each staff member can handle various cases.
8. Creation of Clear Materials and Simulations
At Kakeru Koumuten Co., Ltd., we provide not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar installation guidebook” and a “financial simulation” that takes into account loan interest rates and electricity costs.
The financial simulation can project cumulative income and expenses over 20 to 30 years.
Even customers who are not familiar with solar installations will find our materials easy to understand, including important points and potential drawbacks!
We encourage you to obtain comparative estimates and review plans from other companies!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 to 30 years.
It is crucial to confirm before installation whether it is safe to place them directly on the current roof, as this is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten Co., Ltd., which specializes in roofing, has summarized the items to check before installation.
| 1. Type of roofing material and age | The method of securing the panels varies depending on the roofing material, such as slate, tiles, metal roofs, or flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest a roof renovation first. |
| 2. Condition of the substrate and waterproof sheet | If the sheathing or roofing (waterproof sheet) beneath the roofing material is damaged, it can affect the fastening strength and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, slope, and shading of the roof | The orientation and slope of the roof surface, as well as shading from neighboring houses, trees, and utility poles, will affect power generation. We will create a layout diagram from the drawings and the site, and you can confirm this with the power generation simulation. |
| 4. Shape of the roof and available installation area | The number of panels (installation capacity) that can be placed depends on the shape and size of the roof. The number of panels that can be installed varies by panel size, so we will compare based on the total output of the roof. |
| 5. Method of securing and waterproofing details | We will confirm whether the method involves drilling holes in the roofing material or securing it with brackets. The fastening method varies by technique, so please check the waterproofing treatment of the fastening parts during the estimate. |
| 6. Weight of the roof | The roof will become heavier due to the panels. After investigating the existing roof, substrate, and load-bearing capacity, replacing with lighter roofing materials may be an option if necessary. |
| 7. Location of equipment installation 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 will also affect costs. |
Securing 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) | Waterproofing treatment of fixing parts, cracks or deterioration of slate, condition of the substrate. If deterioration is advanced, consider roof overlay method or replacement first. |
| Tile Roof | Fixed with brackets and methods suitable for the type of tile (even methods that do not drill holes in the tiles will secure to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the investigation results, there may be methods to replace with lighter roofing materials before installation. |
| Metal Roof (Horizontal and Vertical) | Fixed with catch-type brackets that grip the roof material (depends on the combination of roof material and brackets) | Whether the roof material and brackets are compatible, installation conditions from the roof material manufacturer. If compatible, methods that do not drill holes may be available. |
| Flat Roof / Rooftop | Fixed by installing a frame | Type and deterioration status of the waterproof layer, waterproofing details around the frame. Consider in conjunction with the timing of waterproofing work. |
If you plan to renovate the roof 10 to 20 years after installation, there will be additional costs for the removal and reinstallation of solar panels. If the roof is deteriorating, it may be more cost-effective in the long run to renovate to a highly durable roofing material before installation.
Kakeru Koumuten Co., Ltd. specializes in roofing work and can also handle the removal and reinstallation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Isehara City, Kanagawa Prefecture
PossibleSubsidies and Grants
If you are introducing solar panels or storage batteries in Isehara City, there is a possibility that you may be eligible for programs from the “National Government,” “Kanagawa Prefecture,” and “Isehara 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 |
|---|---|---|---|
| Isehara City “Reiwa 8 Year Existing Housing Solar Power Generation Equipment Installation Subsidy” | New installation of solar power generation equipment in existing homes (unused items). Storage batteries are only eligible if applied for together with solar power generation equipment. Installations started before the grant decision are not eligible. Apartment buildings are not eligible. | Solar Power: 30,000 yen per kW (maximum 150,000 yen) Storage Battery: Flat 50,000 yen |
As of June 9, 2026, the budget limit has been reached, and applications are closed (currently, applications cannot be made). The budget was for 20 cases, and the project completion deadline was March 15, 2027. |
| Isehara City “Reiwa 8 Year Energy-Saving Housing Support Subsidy” | Individuals registered as residents in the city who are performing ZEH or insulation window renovations (must have received grant decision from the national or prefectural government). Standalone installation of solar panels or storage batteries is not eligible. | ZEH: 100,000 yen Insulation Window Renovation: The lower amount between the national/prefectural subsidy amount deducted or 100,000 yen. |
As of September 10, 2026, the budget limit has been reached, and applications are closed. |
| Kanagawa Prefecture “Reiwa 8 Year Kanagawa Prefecture Residential Solar Power Generation and Storage Battery Installation Subsidy” | For single-family homes or multi-family dwellings in the prefecture, installing both solar power generation and storage batteries in earthquake-resistant homes. Applications must be made by the individual, and construction must begin after the grant decision. | Solar Power: 70,000 yen/kW Storage Battery: 150,000 yen/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 home storage systems that can be utilized for DR (demand response) with registered products. | Calculated based on an initial effective capacity of 34,500 yen per kWh (subsidy rate within 3/10; maximum 600,000 yen per application). | As of May 29, 2026, the budget has been reached, and public recruitment is closed (currently, applications cannot be made). |
| 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 window (opening) and structural insulation renovations; applications cannot be made for storage battery installation alone. Solar panels are not included as eligible facilities. | Storage Battery: 96,000 yen/unit | Ends as soon as the budget limit is reached. Please check the official site for application status. |
| Kanagawa Prefecture “Reiwa 8 Year Kanagawa Prefecture Self-Consumption Renewable Energy Installation Subsidy” | Corporations and individual business owners filing blue returns (individual residences are not eligible). Solar power must have a generation output of 10kW or more, facilities for business use, and equipment not certified under FIT or FIP, etc. | Solar Power: 80,000 JPY/kW, etc. Storage System: 50,000 JPY/kWh (maximum 5,000,000 JPY) |
Application closed on September 3, 2026 (when the application amount reached the budget limit) |
The solar power subsidy in Isehara City and the residential subsidies from Kanagawa Prefecture require not only the acceptance of applications but also construction to begin after receiving “grant approval”. If construction begins beforehand, it will not be eligible. The city’s program has reached its budget limit and is no longer accepting applications, but please check the city’s official page for information on potential resumption within the fiscal year or applications for the following year. It is not guaranteed that a grant will be awarded upon application, so please confirm before contracting or starting construction.
Kakeru Koumuten will provide guidance on eligibility conditions and business requirements for each program after confirming them.
Isehara City “Reiwa 8 Year Existing Residential Solar Power Generation Equipment Installation Subsidy”
Isehara City provided subsidies for those installing new solar power generation equipment in existing homes. For purchases, the homeowner (or a resident with the homeowner’s consent) is eligible, while for leases, registered businesses under the “Kanagawa Solar Bank System” are eligible.
The subsidy amount is 30,000 JPY per kW for solar power generation (maximum 150,000 JPY), and a flat 50,000 JPY for storage batteries, and the storage battery subsidy is only applicable when applied for together with the solar power generation equipment. The budget was for 20 cases, and applications had to be submitted before starting construction, with construction only to begin after receiving grant approval.
However, the budget limit was reached at 15:25 on June 9, 2026, and application acceptance has ended. There are no plans for resumption mentioned on the city’s official page, so please check the city’s official page (Environmental Measures Division) for future applications.
👉 Click here for Isehara City’s official page
Isehara City “Reiwa 8 Year Energy-Saving Housing Support Subsidy” (ZEH & Insulated Window Renovation)
Isehara City provided subsidies for individuals registered as residents in the city who are constructing, purchasing, or renovating ZEH (Net Zero Energy House) or conducting insulated window renovations. It is a condition to have received grant approval from the national government or Kanagawa Prefecture, with the subsidy amount being 100,000 JPY for ZEH and either the amount after deducting the national and prefectural subsidy for insulated window renovations or 100,000 JPY, whichever is lower.
This program does not solely target the installation of solar panels or storage batteries. Additionally, the budget limit was reached on September 10, 2026, and application acceptance has ended.
👉 Click here for Isehara City’s official page
National Subsidy “DR Home Storage Battery Project (Support Project for Home Storage System Installation for DR Resource Introduction)”
The national government has been implementing the “DR Home Storage Battery Project” to support the installation of home storage batteries.
This program is aimed at those who are newly introducing registered storage systems that can be utilized for demand response (DR) in electricity supply and demand adjustment. 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 subsidy amount of 600,000 JPY per application. There are also conditions such as items contracted or ordered before the grant decision being ineligible.
However, the supplementary budget for fiscal year 2025 reached the budget limit for grant applications on May 29, 2026, and the public offering has ended (the public offering for the previous fiscal year’s supplementary budget also ended on July 2, 2025). Applications are currently not accepted, so please check the official website for future public offerings.
Currently, there are no subsidies confirmed by the government specifically for the installation of solar panels on existing homes.
👉 Click here for the official site of the DR home storage battery project
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Housing Solar Power Generation and Storage Battery Installation Subsidy”
In Kanagawa Prefecture, subsidies are provided to those who introduce both “solar panels” and “storage batteries” to 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.
Conditions include that the storage system must be a registered product, if construction begins before the grant decision, it will be ineligible, and the application must be made by the individual themselves (applications by contractors on behalf of the individual are not allowed). The eligible housing must also ensure seismic performance. Regarding the combination with other subsidy systems, the eligibility may vary by system, so please be sure to check.
In fiscal year 2026, the first application period (May 11 – June 30) and the second application period (September 7 – September 30, first-come-first-served) were conducted, and the second period has reached its application deadline. For future recruitment, please check the official page of Kanagawa Prefecture.
👉 Click here for the official page of Kanagawa Prefecture
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Self-Consumption Type Renewable Energy Installation Subsidy” (for businesses)
Kanagawa Prefecture is also implementing subsidies for businesses introducing “self-consumption type” facilities that use electricity generated from solar panels.
Eligible applicants are corporations or individual business owners filing blue returns, and installations in individual residences are not eligible.
Conditions include that solar power generation must have an output of 10 kW or more, supply electricity to business facilities within the prefecture, and not be facilities certified under FIT or FIP.
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 limit of 5 million yen).
As the application amount reached the budget for the fiscal year 2026, the recruitment was closed on September 3, 2026.
Businesses considering the installation of solar panels on commercial buildings in Isehara City should check the official Kanagawa Prefecture page 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 & water heater removal
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and storage batteries should be confirmed by separating them into “Equipment Costs (Device Costs)” and “Construction Costs”.
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Understanding 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). Storage batteries are compared based on the amount of electricity they can store, expressed in kWh (kilowatt-hours).
The amount of kW that can be installed on a roof varies for each house based on the roof’s shape, orientation, and size. At Kakeru Koumuten, we create layout diagrams from blueprints and on-site surveys to present the installation capacity.
On our pricing page, we list solar panel costs as approximately 800,000 JPY to 1,200,000 JPY for 3 to 5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6 to 10 kW. (These are just approximate amounts and can vary based on wiring length, scaffold range, existing roofing materials, panel layout, etc.)
▶ For details on construction menu and costs for solar panel and storage battery installation, click here
Items to Check in the Estimate (Cost Confirmation)
When comparing estimates, it is common to compare different capacities and equipment by only looking at the amounts. Please check if the following items are clearly stated in each company’s estimate!
| 1. Solar Panels | Check if the manufacturer, model number, output per panel (W), number of panels, and total installation capacity (kW) are listed. |
| 2. Power Conditioner | Check the manufacturer, model number, capacity, number of units, and installation location (indoor/outdoor). Also confirm if it is a type that controls the battery together. |
| 3. Storage Battery | Check the manufacturer, model number, capacity (kWh), the range usable during a power outage (entire house or specific circuits), and installation location. |
| 4. Mounting Frame and Hardware | Check the names of the hardware suitable for the roofing material and the fixing method (whether it is a method that drills holes or a method that clamps and secures). |
| 5. Wiring and Electrical Work | Check the 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 | Check the contents of the waterproof treatment at the fixing parts and whether necessary roof repairs and substrate reinforcements are included. |
| 7. Application | Check how much support is included for applications to the power company, certification applications for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Check the range and quantity of scaffolding. If it is simultaneous with roof work or exterior painting, confirm that the same range and quantity are not counted twice. |
| 9. Removal and Disposal | Check if 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 | Check if it is tax-inclusive or tax-exclusive, conditions under which additional costs may arise, and the details and duration of both manufacturer and workmanship warranties. |
If the capacities differ, both the price and 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 an approximate estimate and a profit simulation up to 30 years later!
If you know the total installation capacity of solar panels on the roof and the capacity of the storage battery, you can obtain an approximate 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)!
Case Studies 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 range |
| Base Mounting Hardware Used |
| Niigata Manufactured / 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 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 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 Isehara City, Kanagawa Prefecture
There are many solar panel installation contractors available in Isehara City, Kanagawa Prefecture, and you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and battery storage installation work, make sure to check the following four points:
● Ensure they have extensive knowledge not only about solar panels but also about roofs
● Confirm the presence of warranties and aftercare maintenance
● Obtain estimates from multiple contractors (three companies 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 of roofs as well as solar panels
Defective 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, leading to leaks
・Solar panels were installed on a roof with a short lifespan, necessitating a remodel 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 unexpected troubles.
▶ Go to “Roof Verification Before Installing Solar Panels” in this article
Confirm the presence of warranties and aftercare maintenance
When choosing a solar installation contractor, make sure to check for warranties. It is important to confirm not only the duration of the warranty but also the scope of coverage, exclusions, and cost conditions.
While the solar panels and battery storage units come with manufacturer warranties, also check for the presence of a workmanship warranty in case leaks occur after installation!
If the contractor provides a workmanship warranty, they may cover leaks that occur after installation within the warranty period and conditions.
Additionally, some contractors offer after-sales service separate from the warranty, so be sure to check if the contractor you are considering has after-sales service.
Changes or damage on the roof can occur in areas that are not visible, so there is a possibility that customers may not notice them themselves.
By conducting inspections of these hidden areas during after-sales maintenance, it becomes easier to detect abnormalities early and prevent major repairs or breakdowns!
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!
After checking the DM, if you wish, we will visit you for after-sales maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting the installation of solar panels, be sure to obtain estimates from multiple contractors.
Even for the same manufacturer and the same construction content, costs may vary, and warranties and after-sales services may differ.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request services from your preferred contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates,
“Check the items in the estimate”
“Type of solar panel”
“Warranties and after-sales services”
and make a careful comparison to make your decision! If the rank of the auxiliary materials is low or if steps are skipped, costs can be reduced, so avoid making decisions based solely on price!
▶ Go to “Breakdown of installation capacity, equipment, and construction costs” in this article
Check if they provide support for subsidy applications
Subsidies may be available for the installation of solar panels and storage batteries, but if the order of procedures is incorrect or if there are deficiencies in the documents, the subsidy may not be granted.
For systems like Kanagawa Prefecture’s housing subsidies, where the contractor cannot apply on behalf of the client, it is reassuring to have a contractor that supports the preparation of necessary documents and the flow of procedures.
Be sure to complete the procedures set by the system (for the prefectural housing subsidy, this means obtaining a grant decision) before proceeding with the construction!
In the case of the prefectural housing subsidy, after the construction is completed, a performance report must be submitted, and the subsidy will be granted after a review! (The flow of procedures varies by system)
▶ Go to “Subsidies and Grants That May Be Applicable in Isehara City” in this Article
Benefits of Introducing Solar Power Systems
The benefits of installing solar panels are summarized in the following 5 points!
Benefit 1: Economic Advantages
The biggest advantage of installing solar panels is the economic benefit!
Although the selling price of electricity has decreased compared to ten years ago, you can benefit by reducing the amount of electricity you buy from the utility by consuming the electricity you generate yourself!
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 systems (under 10kW), the selling price (FIT) for electricity generated from October 2025 onwards is set at “24 yen/kWh for the first four years, and 8.3 yen/kWh from the fifth to the tenth year.” The same price will apply for the 2026 fiscal year. After the fifth year, it is generally more advantageous to use the electricity at home (self-consumption), making the combination with storage batteries a viable option.
👉 For purchase prices and periods, click here
Benefit 2: Utilization of 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!
The reduction in the actual burden amount due to subsidies is a significant advantage!
In the case of Isehara 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 produces low carbon dioxide emissions and reduces dependence on fossil fuels, contributing to the mitigation of global warming.
Solar panels themselves do not emit noise or exhaust gases during the generation process, making them an environmentally friendly method of power generation. (However, devices such as power conditioners may produce operational noise.)
Benefit 4: Expected Heat Insulation Effect!!
By installing panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, this can help reduce the roof temperature, providing a heat insulation effect!
(Note that this does not improve the building’s insulation performance itself.)
Benefit 5: Electricity can be used even during power outages!
If a storage battery is installed, it is possible to use electricity during emergencies such as power outages!
Even without a storage battery, if you have a power conditioner with a self-sustaining function, 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 can be incurred
A maintenance cost that is often overlooked is the roof where the solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reinstalling the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to consider maintenance costs in simulations before introducing solar panels!
Point 2: The risk of leaks increases depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but when fixing hardware to the roofing material or substrate with screws, waterproofing of the fixed parts is crucial.
If the method involves making holes in the roof, there will inevitably be a risk of leaks.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, one option is to replace the roofing material with a metal roof and fix the solar panels using the catch method. (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-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 the case that “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!
How to Choose 1: Compare based on total roof output
When installing solar panels on the roof, it is important to consider how much electricity can be generated in a limited area, and generating more electricity is always better!
Solar panels come in various sizes and outputs depending on the manufacturer.
For example, a 350W output panel and a 400W output panel may seem that the higher output panel is better at first glance.
However, if the size of the panels does not fit well on 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 roof output)
350W × 20 panels = 7kW (total roof output)
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 amount (kWh) will vary depending on conditions such as roof orientation, slope, and shading.
How to Choose 2: Compare based on degradation rate of solar panels
Solar panels have a degradation rate, and their output gradually decreases after 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.
Choosing solar panels by considering the degradation rate as well as the initial output will help avoid regrets!
How to Choose 3: Compare based on warranty period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Regarding the output warranty, some manufacturers offer a 30-year warranty while others provide a 10-year warranty, so it varies!
Since a longer warranty is generally better, let’s check the warranty period and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar and Battery Installation in Isehara City
We have compiled frequently asked questions from customers considering the installation of solar panels and batteries in Isehara City. (Tap to open the answers)
How much does it cost to install solar panels and batteries in Isehara City, Kanagawa Prefecture?
The cost varies depending on the installation capacity, equipment, and the condition of the roof. In the above case study (solar panel 4.3kW + battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
For estimates by capacity, please refer to the solar panel and 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 and battery installation in Isehara City?
As of October 6, 2026, the “Subsidy for Existing Residential Solar Power Generation Equipment” in Isehara City (30,000 yen per kW of solar power, with a maximum of 150,000 yen, and 50,000 yen for batteries) has ended as it reached its budget limit on June 9, 2026. The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power and 150,000 yen per battery) is also nearing the application deadline for the second phase of the 2026 fiscal year, and the national DR household battery project has closed its public recruitment.
Since the application status may change, please check the subsidies and grants section and consult with us before signing a contract.
Can I apply for subsidies after the construction is completed?
For many programs, procedures are required before construction. Both the Isehara City subsidy and the Kanagawa Prefecture subsidy require “commencement of construction after the grant decision,” and if you install it beforehand, 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.
It is possible to install on a slate roof, but it is necessary to check the condition of the roofing material and substrate. The fixing method varies by construction method, and for methods that fix brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation, and if deterioration is advanced, we can also propose methods such as roof overlay or replacement before installation.
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 reinstalling solar panels will be incurred separately. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with 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 for electricity will be 8.3 yen/kWh after the fifth year, making it more beneficial to use it in your home rather than selling it.
Additionally, the subsidy in Kanagawa Prefecture requires the simultaneous introduction of solar panels and storage batteries, and the subsidy in Isehara City was also limited to cases where the storage battery was applied for together with the solar power generation equipment. You can compare “solar only” and “solar + storage battery” in a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing roofs or roofs with shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten, we create a layout diagram from the drawings and site survey, and we will provide you with the installation capacity and power generation simulation.
Isehara City has a terrain that continues from the northwestern Oyama to the southeast with hills, plateaus, and plains, and the shading from surrounding trees and buildings varies from house to house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
In the above construction example (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roof work is performed simultaneously or depending on the shape of the roof and installation capacity.
Additionally, please note that there will be a separate period for applying for subsidies and to the power company, so please consult us as soon as possible.
What is the current selling price (FIT)?
For residential use (less than 10 kW), from the certification after October 2025, the first 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 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 guidance DM and visits for inspections upon request from customers. We can also clean solar panels using a special brush if the power generation is reduced due to dirt.
It is difficult to check areas on the roof by yourself, so please feel free to consult us if you have any concerns.
Can you also renovate roofs that already have solar panels installed?
Yes, we can. Kakeru Koumuten can remove and reinstall solar panels in-house, so we will handle the process of removing the panels, performing the roof overlay (cover method) or re-roofing, and reinstalling them consistently. The removed panels can be stored in our own warehouse.
For costs, please see the solar panel removal and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Isehara City, consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roofing work, and exterior wall work in Isehara City, Kanagawa Prefecture.
We receive requests from many customers, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received positive feedback from numerous customers.
We continue to update our annual construction performance records and will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and re-roofing but also partial roof repairs, exterior painting, and cover installations for exterior walls.
We are also happy to assist with small jobs like 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 us!
“I want to know recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide optimal solutions for your specific requests.
We will never propose unnecessary work that prioritizes profit!
We always stand in the customer’s position and will propose the best construction plan!
We are confident that we will not be outdone 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 we are found to be inferior to other companies, you are free to decline!
Characteristics of Isehara City, Kanagawa Prefecture and Points for Solar Power Work
Isehara City is located almost in the center of Kanagawa Prefecture, with hilly areas, plateaus, and plains extending southeast from the northwest mountain, Oyama.
We have summarized the topography and climate of Isehara City and points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Isehara City and points for solar power work
■ A varied topography from Oyama to the plains, with diverse residential locations
Isehara City’s Topography (Official City Site) describes that the city is located at the southeastern edge of the Tanzawa Mountains, with elevation decreasing from the northwestern peak of Oyama (1,251.7m) towards the southeast. Hinata and Sannomiya are hilly areas, while Isehara’s urban area, Okazaki, and Takamori are on plateaus, and the Ota area is a flat region at about 10m elevation.
The orientation of roofs and surrounding environments vary by region. At Kakeru Koumuten, we will check the shape and orientation of the roof, as well as the shadows cast by nearby trees and buildings on-site, and explain with layout diagrams and power generation simulations.
■ About one-third of the city is forested. Roofs near trees need to be mindful of leaves and dirt.
City Introduction (Official City Site) states that the city covers an area of 55.56 square kilometers, with about one-third consisting of forests and wildlands. Homes close to mountains and trees may experience leaves and dirt on roofs, as well as shadows from trees that can affect power generation. Kakeru Koumuten can also handle solar panel cleaning with specialized brushes and rain gutter cleaning.
■ A climate with abundant rainfall and warmth. Waterproofing of roofs is essential.
The introduction page of the city’s topography indicates that Isehara City has a climate characterized by abundant rainfall and warmth. Power generation may decrease on rainy or cloudy days, so it is reassuring to check through annual power generation simulations. Additionally, roofs where solar panel mounting brackets are installed require reliable waterproofing. Kakeru Koumuten specializes in roofing work and will propose methods suitable for the type of roof.
■ Check the condition of the roof according to its age.
For homes that have been built for several years, it is important to check the condition of the roofing materials and substrate before installing solar panels. Depending on the condition of the roof, installing them simultaneously with roof renovations can reduce future costs for removing and reattaching solar panels.
■ Different subsidy systems for commercial buildings compared to residential ones.
When installing on commercial buildings such as factories, warehouses, stores, or offices, there is a different subsidy system than for residential homes. The Kanagawa Prefecture’s subsidies for businesses closed applications on September 3, 2026, and the Isehara City subsidy for small and medium-sized enterprises for energy-saving equipment does not include solar panels or storage batteries, and applications have also closed.
■ Yokohama’s annual sunshine duration is about 2,018 hours.
Meteorological Agency’s Average Values (1991-2020) indicate that Yokohama’s annual sunshine duration is about 2,018 hours (this is not the value for Isehara City, but for observation points within the prefecture). August has the most sunshine, while June during the rainy season has the least.
Power generation varies by season, so annual power generation simulations and selecting the capacity of storage batteries to match peak electricity usage times are key points.
Our company is based in Kanagawa Prefecture and has handled many exterior construction and solar projects in Isehara 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 about any sudden troubles!
Service Area in Isehara City, Kanagawa Prefecture
Kakeru Koumuten accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Isehara City, Kanagawa Prefecture
Isehara City, Awakubo / Isehara City, Ikehan / Isehara City, Ishida / Isehara City, Isehara / Isehara City, Itado / Isehara City, Utagawa / Isehara City, Osumidai / Isehara City, Oyama / Isehara City, Okazaki / Isehara City, Kasakubo / Isehara City, Kamikasuya / Isehara City, Kamihirama / Isehara City, Kamitani / Isehara City, Kushibashi / Isehara City, Koinaba / Isehara City, Kobe / Isehara City, Koyasu / Isehara City, Sakuradai / Isehara City, Sannomiya / Isehara City, Shimoochiai / Isehara City, Shimo-kasuya / Isehara City, Shimohirama / Isehara City, Shimotani / Isehara City, Shirane / Isehara City, Suzukawa / Isehara City, Zenba / Isehara City, Takamori / Isehara City, Takamori-dai / Isehara City, Tanaka / Isehara City, Tsubonouchi / Isehara City, Nishitomioka / Isehara City, Numame / Isehara City, Hachiman-dai / Isehara City, Higashi-Otake / Isehara City, Higashi-Tomioka / Isehara City, Higashi-Naruse / Isehara City, Hinata / Isehara City, Mitsukejima
・Exterior wall painting in Isehara City, Kanagawa Prefecture, is entrusted to Kakeru Koumuten Co., Ltd.!
・Roof renovation in Isehara City, Kanagawa Prefecture, is entrusted to Kakeru Koumuten Co., Ltd.!
・Exterior renovation in Isehara City, Kanagawa Prefecture, is entrusted to Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd. construction achievements
・Kakeru Koumuten Co., Ltd. after-maintenance
・Kakeru Koumuten Co., Ltd. construction menu and price list
・Kakeru Koumuten Co., Ltd. staff blog and announcements
・Explaining the importance of comparison estimates and key points!
・12 major manufacturers of solar power generation! Also introducing features and selection points!
・What are the installation costs for solar power generation? Thoroughly explaining tips to reduce costs!
・What are the best locations for installing solar power generation? Also introducing key points for selecting installation locations!
・Here is the introduction to solar power generation estimates!
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contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
