Leave the installation of solar panels in Nakagun, Kanagawa Prefecture (Oiso Town and Ninomiya Town) to Kakeru Koumuten Co., Ltd.!
For solar panel and storage battery installation in
Nakaguni (Oiso Town and Ninomiya Town), Kanagawa Prefecture,
trust Kakeru Koumuten Co., Ltd.!
Kakeru Koumuten Co., Ltd. is a specialized exterior renovation company based in Aoba Ward, Yokohama City.
As a company strong in roofing work, we are entrusted withsolar panel installation and storage battery installation considering roofing and waterproofing!
“How to Choose a Solar Panel Contractor in Nakaguni (Oiso Town and Ninomiya Town)”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Nakaguni (Oiso Town and Ninomiya Town)”
We will also explain the above three points!
Installing solar panels carries risks such as“the occurrence of leaks” and other troubles.
To ensure a satisfactory solar panel installation, we recommend obtainingthree estimates!
Table of Contents (tap to open/close)
- Reasons Why Kakeru Koumuten Is Chosen for Solar Panel Installation in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture
- Roof Inspection Before Installing Solar Panels
- Subsidies and Grants That May Be Available in Nakagun (Oiso Town and Ninomiya Town)
- Price List for Solar Panel Installation and Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installation Contractor in Nakagun (Oiso Town and Ninomiya Town)
- Benefits of Introducing Solar Equipment
- Points to Consider When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions About Solar and Battery Installation in Nakagun (Oiso Town and Ninomiya Town)
- If You Are Looking for a Solar Panel Installation Contractor in Nakagun (Oiso Town and Ninomiya Town), Contact Kakeru Koumuten
- Characteristics of Nakagun (Oiso Town and Ninomiya Town) and Points for Solar Construction
- Service Area in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture
Reasons Why Kakeru Koumuten Is Chosen for Solar Panel Installation in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture
The reasons our company is entrusted with solar panel installation by customers in Nakagun (Oiso Town and Ninomiya Town), 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 Also Handle Exterior Renovations Beyond Solar Panel Installation!
Troubles such as leaks caused by the installation of solar panels may be due to 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 knowledge about the roof to avoid maintenance and troubles after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent troubles after solar panel installation!
2.Facilities Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. has organized the following warehouses and material storage areas to provide low-cost, high-quality solar work and exterior renovations.
We have established five bases centered in Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Ownership of Scaffolding Materials
To ensure safety during work on the roof, we own the necessary scaffolding materials for temporary scaffolding based on construction conditions, allowing us to assemble scaffolding ourselves.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also reduce the cost of scaffolding work.
We have scaffolding materials for approximately 50 single-family homes!
Even in Nakagawa (Oiso Town and Ninomiya Town), where residential areas spread from flat coastal areas to hilly regions, our own scaffolding team will plan 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, we canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we canrespond 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 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 how they are installed on the roofing materials!
It is also possible to simulate the revenue and installation costs when introducing solar panels!
Since roofing and exterior wall work often accompany each other, we also provide samples of roofing materials and models that explain the structure, allowing for detailed explanations!
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 a consistent system from inquiry to project completion, Kakeru Koumuten can provide high-quality roof remodeling at reduced costs.
Additionally, one representative will handle everything from the estimate to project completion.
Since the person in charge does not change, whether it’s the sales representative or construction management, smooth communication is possible.
We can perform consistent in-house work from temporary scaffolding installation to exterior wall painting and roof remodeling!
4. Various Permits and Skilled Workers
We have obtained permits for the construction industry and for the collection and transportation of industrial waste!
We also have nationally certified sheet metal workers and painting technicians, and we are confident in our construction skills.
We are capable of handling large-scale roofing projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty, our solar panel installation work comes with our own workmanship warranty (leakage warranty)!
(The workmanship warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovation is performed. The workmanship warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary based on the warranty details.)
Aftercare maintenance is available annually, and we send out notification DM each year.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roof troubles and situations.
Even if we cannot access the roof at high altitudes, we can respond using a drone!
During leakage investigations, we can also conduct inspections using a thermal imaging camera.
If the power generation of the solar panels decreases due to dirt, we can also perform cleaning with a specialized brush.
We will respond according to the customer’s wishes.
7. Human Resource Development
To improve skills, we create various roof models and conduct practical training.
Since the construction methods vary depending on the shape and slope of the roof, we regularly provide technical training to ensure that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
At Kakeru Koumuten Co., Ltd., in addition to “estimates”, “layout diagrams”, and “power generation simulations”, we also provide a “solar construction 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 construction will find the 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.
Confirming “whether it is okay to install them directly on the current roof” before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, which specializes in roofing work, has summarized the items to check before installation.
| 1. 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 shadows of the roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, can affect power generation. We will create a layout diagram from the drawings and the site, and you can check it with the power generation simulation. |
| 4. Shape of the roof and installable area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. The number of panels that can be installed varies depending on the size of the panels, so we will compare 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 method of securing 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 also be an option if necessary. |
| 7. Location of equipment installation and wiring | We will check 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 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) | Waterproof treatment of fixing parts, cracks or deterioration of slate, condition of the substrate. If deterioration is advanced, consider roof overlay (cover method) or replacement first. |
| Tile Roof | Fixed with brackets and methods suited to the type of tile (even methods that do not drill holes in the tiles will secure to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the investigation results, there may be methods to replace with lighter roofing materials before installation. |
| Metal Roof (Horizontal and Vertical) | Fixed with catch-type brackets that grip the roof material (depends on the combination of roof material and brackets) | Whether the roof material and brackets are compatible, installation conditions from the roof material manufacturer. If compatible, methods that do not drill holes may be available. |
| Flat Roof / Rooftop | Fixed by installing a frame | Type and deterioration status of the waterproof layer, waterproofing around the frame. Consideration should be given in conjunction with the timing of waterproofing work. |
If you carry out roof renovations 10 to 20 years after installation, there will be additional costs for the removal and reinstallation of solar panels. If the roof is deteriorating, 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 Oiso Town, Nakagun, Kanagawa Prefecture
▶ Click here for roof renovations in Ninomiya Town, Nakagun, Kanagawa Prefecture
Subsidies and Grants That May Be Applicable in Nakagun (Oiso Town and Ninomiya Town)
If you are introducing solar panels or storage batteries in Nakagun (Oiso Town and Ninomiya Town), there is a possibility that you may be eligible for programs from the “National Government,” “Kanagawa Prefecture,” and “Oiso Town.” It is noted on the official page of Ninomiya Town that the town does not provide its own subsidies for solar power generation or storage batteries.
The following is based on the information confirmed on the official pages of each program as of October 6, 2026. The application status may change due to budget and recruitment periods, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Timing for Subsidy Programs
| System | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Oiso Town “Subsidy for Introduction of Residential Smart Energy Equipment” | Applicants must install new equipment in their own residence within the town during the application year and complete the performance report. Replacement or updating of existing equipment is not eligible. A grant application must be submitted before starting the eligible equipment installation. | Solar Power: 15,000 JPY per kW (maximum 52,000 JPY) Storage Battery: Maximum 50,000 JPY HEMS: Maximum 10,000 JPY Fuel Cell & V2H Charging Device: Maximum 50,000 JPY |
Applications start from April 1, 2026. It may end once the budget limit is reached (please check with the town for the budget amount and current application status). Performance reports are due by the end of March of the fiscal year. |
| Ninomiya Town (Town’s Unique Subsidy) | The town’s official page currently indicates that there are no unique subsidies for the purchase of solar power generation or storage batteries. | (There may be applicable programs from Kanagawa Prefecture or the national government) | The prefecture’s joint purchase project “Solar Power for Everyone’s Home” has a registration deadline of October 29, 2026 (this is a different program from subsidies). |
| Kanagawa Prefecture “Subsidy for Introduction of Residential Solar Power Generation and Storage Batteries for Fiscal Year Reiwa 8” | Must install both solar power generation and storage batteries in a single-family home or apartment building that ensures seismic performance. Applications must be made by the individual, and construction can begin after grant approval. | Solar Power: 70,000 JPY per kW Storage Battery: 150,000 JPY per unit |
Phase 1: May 11, 2026 – June 30, 2026 Phase 2: September 7, 2026 – September 30, 2026 (first-come, first-served) Phase 2 is nearing its application deadline. Please check the prefecture’s official page for future recruitment. |
| National “DR Home Storage Battery Project” (Reiwa 7 Fiscal Year Supplement) | Newly install a registered home storage system that can be utilized for DR (demand response). | Calculated based on a standard amount of 34,500 JPY per initial effective capacity of 1 kWh (subsidy rate within 3/10; maximum 600,000 JPY per application). | Applications have ended as the budget was reached on May 29, 2026 (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 insulation renovation of windows (openings) and the structure; applications cannot be made for just the installation of storage batteries. Solar panels are not included as eligible facilities. | Storage Battery: 96,000 JPY per household | Ends once the budget limit is reached. Please check the official site for application status. |
| Kanagawa Prefecture “Subsidy for Introduction of Self-Consumption Type Renewable Energy for Fiscal Year Reiwa 8” | Corporations and individual business owners filing blue returns（Individual residences are not eligible). Solar power systems must have an output of 10kW or more, and facilities for business use, equipment not certified under FIT/FIP, etc. | Solar Power: 80,000 yen/kW, etc. Storage Systems: 50,000 yen/kWh (maximum 5,000,000 yen) |
Application period ended on September 3, 2026 (when the application amount reached the budget amount) |
As of October 6, 2026, the subsidy for residential properties in Kanagawa Prefecture has passed the application deadline for the second period of Reiwa 8, and the national DR household storage battery project has also ended its public recruitment. The subsidy for Oiso Town will end as soon as the budget limit is reached, and an application for grant must be made before construction begins. The prefectural subsidy for residential properties requires construction to commence after receiving the “Grant Decision”. If construction begins beforehand, it may become ineligible, and applying does not guarantee a grant, so please confirm before contracting or starting construction.
Kakeru Koumuten Co., Ltd. will provide guidance on eligibility conditions for each system after confirming them.
Oiso Town “Subsidy for Introduction of Residential Smart Energy Equipment”
In Oiso Town, subsidies are provided to those who install new smart energy equipment in their own residences within the town during the application year and complete the performance report. Replacing or updating existing equipment is not eligible, and the application for the subsidy must be made before the construction of the eligible equipment.
The subsidy amount is 15,000 yen per kW for solar power generation (maximum 52,000 yen), maximum 50,000 yen for lithium-ion storage systems, and a maximum of 10,000 yen for HEMS devices, with household fuel cells and V2H charging devices (both with a maximum of 50,000 yen) also being eligible. Applications started on April 1, 2026, and applications may close as soon as the budget limit is reached. Performance reports must be submitted by the end of March of the fiscal year. The budget amount and current application status are not listed on the town’s official page, so please contact the Environmental Division of Oiso Town for inquiries.
👉 Here is the official page of Oiso Town
Ninomiya Town (Town’s Unique Subsidy System and Joint Purchase Project with the Prefecture)
The official page of Ninomiya Town currently states that there are no subsidies for the purchase of solar power generation or storage batteries. However, there may be eligibility under the prefectural or national systems, so please check the conditions of each system before contracting or starting construction.
The town’s page mentions the Kanagawa Prefecture’s joint purchase project “Solar Power for Everyone’s Home”. According to the prefecture’s explanation, this system allows for purchases at lower costs by leveraging economies of scale, and the registration deadline for participation is October 29, 2026 (this is a separate system from subsidies). Please check the prefecture’s official page for conditions of participation and the process up to contracting.
👉 Here is the page for the joint purchase project in Kanagawa Prefecture
👉 Here is the official page of Ninomiya Town
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 those who are newly introducing registered storage systems that can be utilized for demand response (DR), and for the fiscal year 2025 supplementary budget, the subsidy amount is determined based on a standard amount of 34,500 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 2024 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 site of the DR Home Battery Project
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Subsidy for Residential Solar Power Generation and Storage Battery Installation Costs”
Kanagawa Prefecture provides subsidies for those who install both “solar panels” and “storage batteries” in their homes.
The subsidy details are 70,000 JPY per 1 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 would be calculated as 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 construction contractors are not allowed). The eligible homes must also ensure seismic performance. The compatibility with other subsidy programs may vary by program, so please be sure to check.
For fiscal year 2026, the first period (May 11 to June 30) and the second period (September 7 to September 30, first-come-first-served) have been accepted, and the second period is approaching its 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 Subsidy for Self-Consumption Type Renewable Energy Installation Costs” (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 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 the 2026 fiscal year, the recruitment was closed on September 3, 2026.
If you are a business considering the installation of solar panels on business buildings in Nakagun (Oiso Town and Ninomiya Town), please 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 separately as “Equipment Costs (Device Costs)” and “Construction Costs.”
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatts). Storage batteries are compared based on the amount of electricity they can store, represented in kWh (kilowatt-hours).
The amount of kW that can be 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 3-5 kW and 1,200,000 JPY to 1,900,000 JPY for 6-10 kW. (These are just rough estimates and can vary based on wiring length, scaffolding range, existing roofing materials, panel layout, etc.)
▶ Construction Menu | Costs for Solar Panel Installation and Storage Battery Installation
Items to Confirm in the Estimate (Cost Verification)
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 | Manufacturer, model number, output per panel (W), number of panels, total installation capacity (kW) are documented. |
| 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 a 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 involves drilling holes or using clamps). |
| 5. Wiring and Electrical Work | Wiring routes and lengths, work around the distribution board, presence of a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment at the fixed points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | Extent of support for applications to the power company, certification application for selling electricity (FIT), and subsidy applications. |
| 8. Scaffolding | Scope and quantity of scaffolding. If roofing work and exterior painting are done simultaneously, check that the same scope and quantity are not double-counted. |
| 9. Removal and Disposal | Whether the removal of existing solar water heaters and old panels, as well as disposal costs for waste materials, are included. |
| 10. Tax Classification and Warranty | Whether prices are tax-inclusive or tax-exclusive, conditions under which additional costs may arise, and details and duration of manufacturer and workmanship warranties. |
If the capacity differs, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome comparisons, so if you bring estimates from other companies, we will explain the differences item by item!
Self-Estimate and Profit and Loss Simulator for Solar Power Generation
With the simulator above,
you can obtain a rough estimate and a profit and loss simulation up to 30 years!
If you know the total installation capacity of solar panels on the roof and the capacity of the storage battery, you can obtain a rough estimate and profit and loss simulation!
*The simulation results are estimates. Actual profits and losses may vary based on conditions such as electricity rates, self-consumption ratios, selling prices, and costs for equipment inspection or replacement.
Customer Feedback
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customer reviews
Asao-ku, Kawasaki City | We received reviews about the ridge cap and rain gutter replacement work!
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customer reviews
Kohoku-ku, Yokohama | We received reviews about the roof overlay (cover method)!
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customer reviews
Kohoku-ku, Yokohama | We Received Reviews About Exterior Painting!
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customer reviews
Hodogaya-ku, Yokohama | We received reviews about our exterior fence construction!
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customer reviews
Tsurumi-ku, Yokohama | We received reviews about roof and exterior wall painting, as well as metalwork and rain gutter replacement work!
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customer reviews
Higashiyamato City, Tokyo | We received reviews about exterior painting and roof overlay (cover method)!
Case Studies of Solar Panel Installations
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh range |
| Base Mounting Hardware Used |
| Niigata Manufactured / Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Details |
| Fixed with 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 will be provided. |
Our Proposal
We visited to provide an estimate and created a layout diagram for the solar panels from the drawings!
The layout diagram shows the arrangement 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 the grant, so we explained it to the customer along with the estimate!
How to Choose a Solar Panel Installation Contractor in Nakagun, Kanagawa Prefecture (Oiso Town and Ninomiya Town)
There are many solar panel installation contractors available in Nakagun, Kanagawa Prefecture (Oiso Town and Ninomiya Town), and it can be confusing to choose the right one.
Therefore, when requesting solar panel installation and battery storage installation work, let’s confirm the following 4 points.
● Have extensive knowledge not only about solar panels but also about roofs
● Check for warranties and after-sales maintenance
● Obtain estimates from multiple contractors (3 companies is a guideline)
● Confirm whether 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
Improper installation of solar panels can be caused by a lack of knowledge and verification regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient verification of roofs and waterproofing
・Solar panels installed on a severely deteriorated roof causing leaks
・Solar panels installed on a roof with a short lifespan, requiring removal and reinstallation within a few years
・Misjudging the type of waterproofing and applying incorrect treatment, 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
Check for warranties and after-sales 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 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!
For contractors that offer a workmanship warranty, if leaks occur after installation, they may be able to respond under the warranty, provided it is within the warranty period and conditions.
Additionally, some contractors offer after-sales service separate from warranties, so be sure to check if the contractor you are considering has after-sales service.
Changes or damage on the roof may occur in areas that are not visible, so there is a possibility that customers may not notice them.
By conducting inspections during after-sales maintenance, we can easily prevent major repairs or failures by detecting 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-sales maintenance and send out annual DM!
After checking the DM, if you wish, we will visit 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 estimate items”
“Type of solar panel”
“Warranties and after-sales services”
and make detailed comparisons to make your decision! If the rank of 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 and Equipment/Construction Costs” in this article
Check if they provide support for subsidy applications
Subsidies may be 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 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 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 subsidy will be granted after a review! (The flow of procedures varies by system)
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 advantage of introducing solar panels is the economic benefit!
While the selling price of electricity has decreased compared to ten years ago, you can benefit by reducing the amount of electricity purchased from power companies through self-consumption of generated electricity!
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, the installation of a storage battery is essential!
For residential use (less than 10kW), the selling price (FIT) from October 2025 onwards will be 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 in the fiscal year 2026. After the 5th 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 Utilizing Subsidies!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the conditions, you may be able to utilize subsidies!
The reduction of the actual burden amount through subsidies is a significant advantage!
In the case of Nakagun (Oiso Town and Ninomiya Town), in addition to national and Kanagawa Prefecture programs, Oiso Town has its own unique subsidy system. Since the application status and order differ by town, please check the official pages of each town.
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 (though devices such as power conditioners do have operational noise).
Benefit 4 Expected Heat Insulation Effect!!
By installing the panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, it can help reduce the temperature rise of the roof, providing expected heat insulation effects!
(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 becomes 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 the solar panels are installed.
If you perform a roof renovation 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 the solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It would be reassuring to ask for a simulation that considers maintenance costs before introducing solar panels!
Point 2: The risk of leaks increases depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but in methods that fix brackets to the roofing material or substrate with screws, waterproofing treatment at the fixed points is crucial.
In methods that involve making holes in the roof, the risk of leaks inevitably arises.
Of course, we will ensure proper waterproofing treatment, but if you are concerned about making holes, 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 the brackets, and it cannot be used with all metal roofs.)
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 also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
Choosing Method 1: Compare by Total Output of the Roof
When installing solar panels on the roof, it is important to consider how much power can be generated in a limited area, and the more power generated, the better!
Solar panels come in various sizes and outputs depending on the manufacturer.
A panel with 350W output and a panel with 400W output may seem that the one with higher output is better at first glance.
However, if the size of the panels does not fit well with the roof, “20 panels of 350W can be installed, while only 15 panels of 400W can be installed,” meaning the number of panels that can be installed may differ even on the same roof due to the size difference.
400W × 15 panels = 6kW (total output of the roof)
350W × 20 panels = 7kW (total output of the roof)
As shown above, even if the output of 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 calculations are for total output (kW). The actual power generation (kWh) will vary depending on conditions such as the roof’s orientation, slope, and shading.
Choosing Method 2: Compare by Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases 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 itself.
Choosing solar panels while considering the degradation rate, rather than just the initial output, will help you avoid regrets!
Choosing Method 3: Compare by Warranty Period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Regarding the output warranty, some manufacturers offer a 30-year warranty, while others provide a 10-year warranty, so it varies widely!
A longer warranty is always better, so let’s check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Panel and Storage Battery Installation in Nakaguni (Oiso Town and Ninomiya Town)
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Nakaguni (Oiso Town and Ninomiya Town). (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Nakaguni (Oiso Town and Ninomiya Town), Kanagawa Prefecture?
The cost varies depending on the installation capacity, equipment, and roof condition. In the above construction example (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
Guidelines for costs by capacity are published on the solar panel installation and storage battery installation pricing page. We will create a layout diagram from the drawings and site survey and provide a free estimate!
Are there any subsidies available for solar panel and storage battery installation in Nakaguni (Oiso Town and Ninomiya Town)?
As of October 6, 2026, Oiso Town has its own subsidy program (please check with Oiso Town for the status as it will end once the budget limit is reached). Ninomiya Town has announced that it does not provide its own subsidies for solar power generation or storage batteries. Kanagawa Prefecture’s subsidies (70,000 yen/kW for solar power and 150,000 yen per unit for storage batteries) are approaching the application deadline for the second phase of the 2026 fiscal year, and the national DR household storage battery project has ended its public recruitment. Please check each official page for future applications.
Since the application status may change, please refer to the subsidy and grant section and consult with us before signing a contract.
Can I apply for subsidies after the construction is completed?
For many programs, procedures are required before construction. The subsidy for Oiso Town requires an application for disbursement before construction begins, and Kanagawa Prefecture’s subsidy requires “commencement of construction after disbursement decision,” so if you install it first, you may be excluded from eligibility. Procedures differ by program.
Since the order of procedures varies by program, please confirm before signing a contract or starting construction.
Can solar panels be installed on 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 if the method involves fixing brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten Co., Ltd. is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation and suggest methods such as roof overlay (cover method) or complete replacement if deterioration is progressing.
My roof is old. Should I do a roof renovation first?
It depends on the condition of the roof. If a roof renovation is needed within 10 to 20 years after installation, there will be additional costs for removing and reinstalling solar panels. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with durable roofing materials before installation.
Please consult us about the installation process after confirming the condition of the roof through a site survey!
Should I install a storage battery together with the solar panels?
If you want to use the generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price for electricity will be 8.3 yen/kWh after the fifth year, making it more advantageous to use it at home rather than selling it.
Additionally, Kanagawa Prefecture’s subsidy requires the simultaneous introduction of solar panels and storage batteries. Please check the official page of Oiso Town for the conditions of subsidies for each facility. You can compare “solar panels only” and “solar panels + storage battery” through a profitability simulation.
How many kW can I install on my roof? Is it okay for north-facing or shaded roofs?
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.
The Nakagun area (Oiso Town and Ninomiya Town) has a varied terrain from flat areas facing the sea to hilly regions, and the shading from neighboring houses, trees, and slopes varies from house to house. You can check the expected power generation through the power generation simulation.
How long will the construction period be?
For the above construction example (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roofing work is done simultaneously or depending on the shape of the roof and installation capacity.
Additionally, please note that there will be a separate period for applying for subsidies and to the power company, so please consult us early.
What is the current selling price (FIT)?
For residential use (less than 10 kW), from the certifications after October 2025, the first 4 years will be 24 yen/kWh, and from the 5th to the 10th year it will be 8.3 yen/kWh, and the same prices will apply for the 2026 fiscal year.
The idea is to recover initial costs quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides profitability simulations that take 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 notices and visits customers who wish for inspections. We can also clean solar panels with a special brush if the power generation decreases due to dirt.
The roof is a place that is difficult to check by yourself, so if you have any concerns, please feel free to consult us.
Can you also handle renovations for roofs that already have solar panels installed?
Yes, it is possible. Kakeru Koumuten Co., Ltd. can detach and reattach solar panels in-house, allowing us to remove the panels, perform roof overlay (cover method) or re-roofing, and then reinstall them consistently. The removed panels can be stored in our own warehouse.
For costs, please refer to the solar panel detachment and water heater removal pricing page.
If you are looking for a solar panel installation company in Nakagun (Oiso Town and Ninomiya Town), please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including roof work and wall work, in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture, including solar panels.
We have received requests from many customers, including renovation companies and real estate companies, who have contacted us!
Kakeru Koumuten promises “high-quality renovations at low cost”, and we have received great feedback from many customers.
We continue to update our construction performance records every year, and we will strive to improve quality to satisfy even more customers in the future.
Our company can perform all exterior renovations, not only roof overlay work and re-roofing but also partial roof repairs, exterior painting, and exterior cover methods.
We are also happy to handle small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide emergency measures without setting up scaffolding, as long as safety can be ensured, so please consult us!
“I want to know recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide the best solutions for your specific requests.
We will never propose unnecessary work focused on profit!
We always stand in the customer’s position and propose the optimal construction plan!
We are confident that we will not be outdone in terms of cost, quality, and organization compared to other companies for exterior work!
We are confident, so we welcome competitive estimates!
Estimates are completely free, and if our company is found to be inferior to others, you are free to decline!
Characteristics of Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture, and Points of Solar Work
Chūgun is a region consisting of two towns: Oiso Town and Ninomiya Town. According to the official page of Oiso Town, it has an area of 17.23 km², with a somewhat elongated shape approximately 7.6 km east-west and 4.1 km north-south. It borders Sagami Bay to the south and the hilly areas of the Oiso landform, including Kōraiyama and Takatōyama, to the north, with 65% of the town occupied by hilly terrain, while the urban area is formed along the flat land of National Route 1. The official page of Ninomiya Town states that it has an area of about 9 km², measuring 3.8 km north-south and 3.3 km east-west, facing Sagami Bay to the south and bordered by Nakai Town to the north, with the Odawara City across the Nakagawa (Oshikirigawa) to the west.
Below are the characteristics of Chūgun (Oiso Town and Ninomiya Town) and points to consider when installing solar panels and storage batteries (tap to open).
View the characteristics of Chūgun (Oiso Town and Ninomiya Town) and points for solar construction
■ Two towns facing Sagami Bay. Consideration for salt air in homes near the sea
Oiso Town and Ninomiya Town both face Sagami Bay to the south. In locations close to the sea, the salt content in the sea breeze can affect the fixtures and equipment around the roof. It is important to choose panels, mounting frames, fixtures, and power conditioners that meet the installation conditions set by the manufacturer (such as distance from the coast and salt-resistant specifications) suitable for your location.
■ From flat areas to hilly terrain. Check the shadows cast by slopes and greenery
Oiso Town has 65% of its area covered by hilly terrain, and the northern part of Ninomiya Town is also characterized by the backdrop of the Tanzawa Mountains. In homes located in flat areas, shadows from neighboring houses and utility poles are the main concern, but in homes closer to hilly areas, shadows from slopes and surrounding trees may change the sunlight exposure in the morning and evening. Kakeru Koumuten Co., Ltd. creates layout diagrams based on blueprints and the actual site conditions, allowing you to confirm through power generation simulations.
■ Roofs that easily accumulate fallen leaves and branches should consider ease of cleaning
In residential areas close to hilly terrain with many trees, fallen leaves and branches may easily accumulate on panels and rain gutters. If dirt such as fallen leaves and dust accumulates on the roof, it may affect power generation, so it is important to consider the arrangement of panels and the ease of cleaning and inspecting rain gutters.
■ In low-lying areas near rivers and the sea, also check the installation locations of equipment
The western side of Ninomiya Town borders Odawara City across the Nakagawa (Oshikirigawa). In low-lying areas near rivers and the sea, the risk of flooding can vary depending on your location. When deciding on the installation locations for storage batteries and power conditioners, it is reassuring to check the flooding assumptions for your location on a hazard map.
■ Different subsidies for each town. Oiso Town has its own system, while Ninomiya Town provides information on the prefecture’s joint purchase project
Oiso Town offers a subsidy for the introduction of residential smart energy equipment, which will end once the budget limit is reached. Ninomiya Town does not provide its own subsidies for solar power generation or storage batteries, as indicated on the official town page, and introduces the Kanagawa Prefecture’s joint purchase project. It is important to check the systems in your town in advance, along with the timing of the construction.
■ Check the roof condition according to the age of the building
For homes that have aged over the 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 help reduce future costs for removing and reinstalling the solar panels.
Our company is based in Kanagawa Prefecture and handles many exterior construction and solar projects in Nakagun (Oiso Town and Ninomiya Town).
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 urgent issues!
Service Area in Nakagun, Kanagawa Prefecture (Oiso Town and Ninomiya Town)
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Nakagun, Kanagawa Prefecture (Oiso Town and Ninomiya Town)
List of Areas in Oiso Town
Oiso Town Ikusawa/Oiso Town Ishigamidai/Oiso Town Oiso/Oiso Town Tsukigyo/Oiso Town Kuroiwa/Oiso Town Kōfu Shinjuku/Oiso Town Kōfu Hongō/Oiso Town Kōrai/Oiso Town Terasaka/Oiso Town Nishikubo/Oiso Town Nishikoiso/Oiso Town Higashikoiso/Oiso Town Higashimachi/Oiso Town Mushikubo
List of Areas in Ninomiya Town
Ninomiya Town Isshiki/Ninomiya Town Kawai/Ninomiya Town Nakazato/Ninomiya Town Ninomiya/Ninomiya Town Fujimigaoka/Ninomiya Town Matsune/Ninomiya Town Midorigaoka/Ninomiya Town Yamanishi/Ninomiya Town Yurigaoka
・Exterior wall painting in Oiso Town, Nakagun, Kanagawa Prefecture is entrusted to Kakeru Koumuten Co., Ltd.!
・Exterior wall painting in Ninomiya Town, Nakagun, Kanagawa Prefecture is entrusted to Kakeru Koumuten Co., Ltd.!
・Roof renovation in Oiso Town, Nakagun, Kanagawa Prefecture is entrusted to Kakeru Koumuten Co., Ltd.!
・Roof renovation in Ninomiya Town, Nakagun, Kanagawa Prefecture is entrusted to Kakeru Koumuten Co., Ltd.!
・Exterior renovation in Oiso Town, Nakagun, Kanagawa Prefecture is entrusted to Kakeru Koumuten Co., Ltd.!
・Exterior renovation in Ninomiya Town, Nakagun, 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 comparative estimates and points to consider!
・Top 12 solar power generation manufacturers! Introducing features and selection points!
・What are the installation costs for solar power generation? Thoroughly explaining tips to reduce costs!
・Where is the best place to install solar power generation? 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!
