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 company specializing in exterior renovations based in Aoba Ward, Yokohama City.
As a company strong in roofing work, we are entrusted with solar panel and storage battery installations 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 obtaining three or so 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
- Possible Subsidies and Grants 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’re 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 Key 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 why we are 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 replicated by other companies, which have received high praise from many customers.
so we would be grateful if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Can Also Handle Exterior Renovations Besides Solar Panel Installation!
Issues such as leaks that occur during solar panel installation may be caused by insufficient checks on the roof and waterproofing at the installation site.
Even if 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 someone knowledgeable 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 prepared the following warehouses and material storage areas to provide low-cost, high-quality solar and exterior renovation work.
We have established five bases centered around Yokohama City, Kanagawa Prefecture for material storage and showrooms.
In-house Scaffolding Materials
To ensure safety during work on the roof, we own the scaffolding materials necessary for temporary scaffolding according to the construction conditions, allowing us to assemble scaffolding in-house.
By not outsourcing scaffolding work and using our own scaffolding team, we can also cut costs for scaffolding work.
We own scaffolding materials for approximately 50 houses!
In Nakagun (Oiso Town and Ninomiya Town), where residential areas spread from flat coastal areas to hilly regions, our in-house scaffolding team plans scaffolding according to the local conditions.
Storage of Materials in Our Large Warehouse
We store roofing materials and paints, and we can also store removed solar panels.
By ordering a large quantity of materials at once, you canpurchase materials at a lower cost!
Additionally, we always have a stock of roofing materials, so we canrespond quickly in emergencies!
In-house sorting and transportation of waste materials
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior renovation dedicated showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on roofing materials!
You can also simulate the potential earnings and costs associated with the installation of solar panels!
Since roofing and exterior wall work often accompany each other, we also have samples of roofing materials and models that explain the structure, allowing for detailed explanations!
3.All work performed by our own team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having Kakeru Koumuten handle everything from inquiries to project completion in a consistent manner, we can keep costs down and provide high-quality roof renovations.
Additionally, one representative will assist you from the estimate to the completion of the work.
Since the same person will handle sales and construction management, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation to exterior wall painting and roof renovations!
4. Various Permits and Skilled Workers
We have obtained construction industry licenses and permits for industrial waste collection and transportation!
We also have nationally certified sheet metal workers and painting technicians, and we are confident in our construction techniques.
We can also handle large-scale roofing projects such as factories!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation work, our own construction warranty (leakage warranty) is also included!
(The construction warranty for solar panel installation is for 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovations are carried out. The construction warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary depending on the warranty details.)
Aftercare is available annually, and we send out notification DM every year.
If you have questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roofing troubles and situations.
Even if you cannot access the roof at high altitudes, we can utilize drones to assist!
During leak investigations, we can also conduct surveys using a thermal imaging camera.
If the power generation of solar panels decreases due to dirt, we can provide 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 so that each staff member can handle various cases.
8. Creation of Easy-to-Understand Materials and Simulations
At Kakeru Koumuten, we provide not only “estimates,” “layout diagrams,” and “power generation simulations” but also a “solar construction guidebook” and a “profit and loss simulation” that takes into account loan interest rates and electricity costs.
The profit and loss simulation can be created for projected cumulative profits and losses over 20 to 30 years.
Even customers who are not familiar with solar construction will receive easy-to-understand materials that include points to consider and disadvantages!
We encourage you to obtain comparative estimates and compare them with other companies’ plans!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 to 30 years.
Confirming “Is it okay to install them directly on the current roof?” before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, which specializes in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Age | The fixing method varies depending on the roofing materials such as slate, tiles, metal roofs, and flat roofs (roof waterproofing). If the remaining lifespan of the roofing material is short, we may suggest roof renovation first. |
| 2. Condition of the Substrate and Waterproof Sheet | If the sheathing or roofing (waterproof sheet) beneath the roofing material is damaged, it will affect the fastening strength and waterproofing. We will also check for any signs of leaks. |
| 3. Orientation, Slope, and Shadows of the Roof | The orientation and slope of the roof surface, as well as shadows from neighboring houses, trees, and utility poles, will affect the power generation. We will create a layout diagram from the drawings and the site, and you can check it with a power generation simulation. |
| 4. Shape of the Roof and Usable Area | The number of panels that can be installed (installation capacity) is determined by the shape and size of the roof. Since the number of panels that can be installed varies depending on the size of the panels, we will compare based on the total output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will confirm whether the method involves drilling holes in the roofing material for fixing or using brackets to secure the roofing material. The fixing method varies by technique, so please check the waterproofing treatment method for the fixing parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels being installed. After investigating the existing roof, substrate, and load-bearing capacity, replacing with lighter roofing materials may also be an option if necessary. |
| 7. Installation Location of Equipment 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 the cost. |
Fixing Methods and Checkpoints by Roofing Material
| Roof Material | Main Fixing Method | Pre-Installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (e.g., fixing brackets to the roof material and substrate with screws) | Waterproofing treatment of fixed 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 fix to the substrate) | Type and condition of tiles, substrate, load-bearing capacity. Depending on the investigation results, there may be methods to replace with lightweight roofing materials before installation. |
| Metal Roof (Horizontal and Vertical) | Fixed with catch-type brackets that grip the roof material (depends on the combination of roof material and brackets) | Whether the roof material and brackets are compatible, installation conditions from the roof material manufacturer. If compatible, methods that do not drill holes may be available. |
| Flat Roof / Rooftop | Fixed by installing a frame | Type and deterioration status of the waterproof layer, waterproofing around the frame. Consider in conjunction with the timing of waterproofing work. |
If you carry out roof renovations 10 to 20 years after installation, there will be additional costs for removing and reinstalling solar panels. If the roof is deteriorating, renovating to a highly durable roofing material before installation may help reduce costs in the long run.
Kakeru Koumuten Co., Ltd. specializes in roofing work and can also handle the removal and reinstallation of solar panels in-house, so please consult us according to the condition of your roof!
▶ Click here for roof renovations in Oiso Town, Nakagun, Kanagawa Prefecture
▶ Click here for roof renovations in Ninomiya Town, Nakagun, Kanagawa Prefecture
Possible Subsidies and Grants in Nakagun (Oiso Town and Ninomiya Town)
If you introduce solar panels or storage batteries in Nakagun (Oiso Town and Ninomiya Town), there is a possibility that the systems of “the national government,” “Kanagawa Prefecture,” and “Oiso Town” may apply. Ninomiya Town does not provide its own subsidies for solar power generation or storage batteries, as stated on the town’s official page.
The following is based on the content confirmed on the official pages of each system as of October 6, 2026. The application status may change depending on the budget and recruitment period, 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 updates of existing equipment are not eligible. Application for subsidy must be submitted before starting construction of eligible equipment. | 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-Specific Subsidy) | The town’s official page currently indicates that there are no town-specific 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 “Everyone’s Home Solar Power” has a registration deadline of October 29, 2026 (this is a separate program from subsidies). |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Subsidy for Residential Solar Power Generation and Storage Battery Installation” | Installation of both solar power generation and storage batteries in earthquake-resistant single-family homes or multi-family residences within the prefecture. Applications must be made by the applicant, and construction can begin after the subsidy decision. | 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 has reached its application deadline. Please check the prefecture’s official page for future recruitment. |
| National “DR Home Storage Battery Project” (Fiscal Year 2025 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 1 kWh at 34,500 JPY (subsidy rate within 30% and maximum 600,000 JPY per application). | Applications have ended as of May 29, 2026, when the budget was reached (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 renovations 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 unit | Ends once the budget limit is reached. Please check the official site for application status. |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Subsidy for Introduction of Self-Consumption Type Renewable Energy” | 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/FIP, etc. | Solar Power: 80,000 yen/kW, etc. Storage System: 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 housing subsidies in Kanagawa Prefecture have 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 in Oiso Town will end as soon as the budget limit is reached, and an application for grant must be made before starting construction. The prefectural housing subsidy requires construction to begin after receiving the “Grant Decision”. If construction starts beforehand, it may become ineligible, and applying does not guarantee that a grant will be awarded, so please confirm before contracting and starting construction.
Kakeru Koumuten will guide you on the 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. Replacement or updates of existing equipment are not eligible, and the application for the subsidy must be made before starting 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 eligible. Applications started on April 1, 2026, and may end once 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.
👉 Click here for Oiso Town’s official page
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 provided by the town. However, there may be applicable programs from Kanagawa Prefecture or the national government, so please check the conditions of each program before contracting and 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, it is a system that allows purchases at lower costs by leveraging scale advantages, with the registration deadline for participation being October 29, 2026 (this is a separate program from subsidies). Please check the conditions for participation and the process up to contracting on the prefecture’s official page.
👉 Click here for Kanagawa Prefecture’s joint purchase project page
👉 Click here for Ninomiya Town’s official page
National Subsidy “DR Home Battery Project (Support Project for Home Storage Systems for DR Resource Introduction)”
The government has been implementing the “DR Home Battery Project” to support the installation of home storage batteries.
This program targets those who are newly introducing registered storage systems that can be utilized for demand response (DR). In the fiscal year 2025 supplementary budget, the subsidy amount is determined based on a standard amount of 34,500 JPY per initial effective capacity of 1 kWh, with a subsidy rate of up to 30% and a maximum subsidy 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 supplementary budget for fiscal year 2025 reached the budget limit for grant applications on May 29, 2026, and the public offering has ended (the previous fiscal year’s supplementary budget also ended on July 2, 2025). Applications are currently not possible, so please check the official website for future public offerings.
Additionally, there are currently no subsidies confirmed for the installation of solar panels on existing homes.
👉 Click here for the official website of the DR Home Battery Project
Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Subsidy for Residential Solar Power Generation and Storage Battery Installation Costs”
In Kanagawa Prefecture, subsidies are provided for those who install both “solar panels” and “storage batteries” in their homes.
The subsidy details are 70,000 JPY per kW of solar power generation output and 150,000 JPY per storage system.
For example, if you install a 4 kW solar panel and one storage battery, the subsidy amount would be calculated as 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 not be eligible, and the application must be made by the individual (proxy applications by contractors are not allowed). The target residence must also ensure seismic performance. The compatibility with other subsidy programs may vary by program, so please be sure to check.
In fiscal year 2026, the first phase (May 11 to June 30) and the second phase (September 7 to September 30, first-come-first-served) were conducted, and the second phase has reached its application deadline. For future recruitment, please check the official page of Kanagawa Prefecture.
👉 Click here for the official 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 by 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 an output of 10kW or more, supply electricity to business facilities within the prefecture, and not be equipment that has received FIT/FIP certification, among other conditions.
The subsidy amount is 80,000 yen per kW for solar power generation and 50,000 yen per kWh for the accompanying storage system (with a maximum of 5 million yen), among other details.
As the application amount reached the budget amount for Reiwa 8, the recruitment was closed on September 3, 2026.
Businesses considering the installation of solar panels on commercial buildings in Nakagun (Oiso Town and Ninomiya Town) should check the official Kanagawa Prefecture page for the next recruitment.
👉 Click here for details
Solar Panel Installation & Storage Battery Installation Price List
⇧ Installation Menu | Click here for costs related to solar panel removal & water heater removal
Breakdown of Installation Capacity, Equipment, and Construction Costs
It is important to check the costs of solar panels and storage batteries by separating them into “equipment costs (device costs)” and “construction costs.”
Even for the same “solar panel installation set,” the amount can vary greatly depending on the installation capacity, equipment grade, and roof condition.
Considerations for Installation Capacity (kW) and Storage Battery Capacity (kWh)
The installation capacity of solar panels is determined by “output of one panel (W) × number of panels”, with the unit being kW (kilowatts). Storage batteries are compared in terms of the amount of electricity they can store, represented in kWh (kilowatt-hours).
The amount of kW that can be placed on the roof varies for each house depending on the shape, orientation, and size of the roof. Kakeru Koumuten Co., Ltd. will create a layout diagram based on the drawings and on-site survey to present the installation capacity.
On our pricing page, we list solar panels as approximately 800,000 yen to 1,200,000 yen for 3-5 kW, and 1,200,000 yen to 1,900,000 yen for 6-10 kW. (These are just approximate amounts and can vary based on wiring length, scaffolding range, existing roofing materials, panel layout, etc.)
▶ Service Menu | Click here for costs of solar panel installation and storage battery installation
Items to Check in the Quotation (Cost Confirmation)
When comparing costs in competitive quotations, it is common to compare different capacities and equipment. Please check if the following items are clearly stated in each company’s quotation!
| 1. Solar Panels | Manufacturer, model number, output of one panel (W), number of panels, total installation capacity (kW) are listed. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls in conjunction with the storage battery. |
| 3. Storage Battery | Manufacturer, model number, capacity (kWh), range usable during power outages (entire house or specific circuits), installation location. |
| 4. Mounting Frame and Hardware | Name of hardware suitable for roofing materials and method of securing (whether it is a method that drills holes or a method that clamps and secures). |
| 5. Wiring and Electrical Work | Wiring route and length, work around the distribution board, presence of a monitor to check power generation. |
| 6. Roof Reinforcement and Waterproofing | Details of waterproofing treatment for fixed parts, 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 it is simultaneous with roof work or exterior painting, check that the same scope and quantity are not counted twice. |
| 9. Removal and Disposal | Whether the removal of existing solar thermal water heaters or old panels and disposal costs for waste materials are included. |
| 10. Tax Classification and Warranty | Whether it is tax-inclusive or tax-exclusive, conditions under which additional costs may arise, and details and duration of manufacturer warranty and workmanship warranty. |
If the capacity differs, both the price and the power generation will change. Kakeru Koumuten Co., Ltd. welcome price comparisons, so if you bring estimates from other companies, we will explain the differences item by item!
Self-Estimate and Profit Simulation for Solar Power Generation
With the simulator above,
you can perform a rough estimate and a profit simulation up to 30 years later!
If you know the total installation capacity of the solar panels on the roof and the capacity of the storage battery, you can get a rough estimate and profit simulation!
*The simulation results are estimates. Actual profits may vary based on assumptions such as electricity rates, self-consumption ratios, selling prices, and costs for equipment inspection and 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 |
| Base Mounting Hardware Used |
| Niigata Manufactured / Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Details |
| Fixed by gripping the horizontal metal roof with catch type hardware (Catch Method) |
| Price Range |
| 2,200,000 JPY～2,300,000 JPY *Due to the grant being provided, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8 to 9 years (self-consumption) *The grant amount and recovery estimate are based on the system and calculations at the time of construction and may differ under the current system. |
| Construction Period |
| About 3 days |
| Completion Month |
| April 2025 |
| Inquiry Details |
| I am considering the installation of solar panels and storage batteries. I heard that grants are available, and I would like to know how much can be provided. |
Our Proposal
We visited to provide an estimate and created a layout diagram for the solar panels from the drawings!
The layout diagram shows the arrangement when solar panels are 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 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 you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and storage battery installation work, let’s check the following four points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the existence of warranties and after-sales maintenance
● Obtain estimates from multiple contractors (three companies as 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 sometimes be caused by a lack of knowledge and verification regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient verification of roofs and waterproofing
・Solar panels were installed on a severely deteriorated roof, leading to leaks
・Solar panels were installed on a roof with a short lifespan, requiring renovations to detach and reattach the solar panels within a few years
・Misjudging the type of waterproofing led to incorrect processing and subsequent leaks
and more
When installing solar panels, understanding the condition and type of the existing roof allows you to avoid unnecessary expenses and unexpected troubles.
▶ Go to “Roof Verification Before Installing Solar Panels” in this article
Confirm the existence of warranties and after-sales maintenance
When choosing a solar installation contractor, let’s check for the existence of warranties. It is important to confirm not only the duration of the warranty but also the scope of coverage, disclaimers, and cost conditions.
While the solar panels and storage batteries come with a manufacturer’s warranty, it is also important to check for the existence 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-service separate from warranties, so be sure to check if the contractor you are considering has after-service.
Changes or damages on the roof may occur in areas that are not visible, so there is a possibility that customers may not notice them themselves.
By conducting inspections in after-maintenance, we can easily prevent major repairs or failures by discovering abnormalities early!
Kakeru Koumuten Co., Ltd. provides a leak warranty as a workmanship guarantee for solar panel installations. (The warranty for solar panel installation is 10 years, and depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovation is performed.)
We also conduct after-maintenance and send out DM every year!
Please check the DM, and if you wish, we will visit for after-maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, be sure to obtain estimates from multiple contractors.
Even for the same manufacturer and the same work content, costs may vary, and warranties and after-services may differ.
Additionally, obtaining multiple estimates makes it easier to negotiate prices.
To request from your preferred contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check the following:
“Check the items in the estimate”
“Type of solar panels”
“Warranties and after-services”
Make sure to compare these details carefully! If the quality of the auxiliary materials is low or if steps are skipped, costs can be reduced, so avoid judging solely based on price!
▶ Go to “Breakdown of Installation Capacity and Equipment/Construction Costs” in this article
Check if they provide support for subsidy applications
There may be subsidies available for solar panel installation and battery installation, 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 your behalf and personal application is required, it is reassuring to have a contractor that supports the preparation of necessary documents and the flow of procedures.
Complete the procedures specified for each system (for the prefectural housing subsidy, this means obtaining a grant decision) before proceeding with the construction!
For the prefectural housing subsidy, after the construction is completed, a performance report must be submitted, and the flow will be to undergo a review before the grant is provided! (The flow of procedures varies by system)
Benefits of Installing Solar Power Systems
The benefits of installing solar panels are as follows!
Benefit 1: Economic Benefits
The biggest benefit of installing solar panels is the economic advantage!
While the selling price of electricity has decreased compared to ten years ago, you can gain benefits by reducing the electricity you buy from power companies by consuming the electricity you generate!
As electricity prices rise, the ability to cover your consumption with solar power becomes attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
For residential (under 10kW) selling prices (FIT), the price setting from certifications after October 2025 will be “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 often more advantageous to use it at home (self-consumption), making the combination with storage batteries a viable option.
👉 Ministry of the Environment and Energy | For purchase prices, periods, etc., click here
Benefit 2: You Can Utilize Subsidies!
The conditions and amounts of subsidies vary by prefecture and municipality, but if you meet the requirements, you may be able to utilize subsidies!
Reducing the actual burden through subsidies is a significant advantage!
In the case of Nakagun (Oiso Town and Ninomiya Town), in addition to national and Kanagawa Prefecture systems, Oiso Town has its own unique subsidy system. The application status and order differ by town, so 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. (However, devices like power conditioners may have operational noise.)
Benefit 4: Heat Insulation Effects Can Be Expected!!
By installing them on the roof or rooftop, the panels block direct sunlight to the roof.
Especially in summer, it can help reduce the temperature rise of the roof, providing expected heat insulation effects!
(Note that this does not improve the 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 even during emergencies such as power outages!
Even without a storage battery, if you have a power conditioner with autonomous operation capabilities, you may be able to use electricity from a dedicated outlet during daytime generation.
(The devices, output, and duration that can be used during a power outage vary depending on the model and wiring method.)
What points should be noted when introducing solar power generation?
Next, we will explain the “three points to note” when installing solar panels!
Point 1 Maintenance costs can be incurred
A maintenance cost that is particularly easy to overlook 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 deteriorated, 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 consider maintenance costs in simulations before introducing solar panels!
Point 2 The risk of leaks increases depending on the roofing material
The fixing methods for slate roofs and tile roofs vary by construction method, but in methods that fix brackets to the roofing material or substrate with screws, waterproofing of the fixed parts is crucial.
In methods that involve making holes in the roof, the risk of leaks inevitably arises.
Of course, we will ensure proper waterproofing, but if you are concerned about making holes, replacing the roofing material with a metal roof and fixing the solar panels using the catch method is also an option. (The catch method has compatibility conditions between the roofing material and the brackets, 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, switching to a lightweight 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!
How to Choose 1: Compare by Total Output of the Roof
When installing solar panels on the roof, it is important to know how much power can be generated in a limited area, and generating more power is always 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 panel does not fit well with the roof, there may be cases where “20 panels of 350W can be installed” and “15 panels of 400W can be installed,” leading to different numbers of panels that can be installed on the same roof due to size differences.
400W × 15 panels = 6kW (total output of the roof)
350W × 20 panels = 7kW (total output of the roof)
As shown above, even if the output of 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 is a calculation of total output (kW). The actual power generation amount (kWh) varies depending on conditions such as the orientation, slope, and shading of the roof.
How to Choose 2: Compare by Degradation Rate of Solar Panels
Solar panels have a degradation rate, and their output gradually decreases over 10 years and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output guarantee value is a standard figure for the warranty and does not indicate the actual degradation rate or power generation amount.
By considering the degradation rate as well as the initial output, you can choose solar panels without regrets!
How to Choose 3: Compare by Warranty Period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
Regarding output warranties, some manufacturers offer a 30-year warranty while others offer a 10-year warranty, so it varies!
Longer warranties are better, so be sure to check the warranty period and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in 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)?
The cost varies depending on the installation capacity, equipment, and condition of the roof. In the above construction example (solar panel 4.3kW + storage battery, completed in April 2025), it was 2.2 million yen to 2.3 million yen.
Guidelines for different capacities are published on the solar panel and storage battery installation pricing page. We will create a layout diagram from the drawings and site survey and provide a free estimate!
Are there any subsidies available for solar power and storage battery installation in 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 and storage batteries. The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power and 150,000 yen/unit for storage batteries) is approaching the application deadline for the second phase of fiscal year 2026, and the national DR household storage battery program 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 starting construction, and the Kanagawa Prefecture subsidy requires “starting construction after the disbursement decision,” so if you install it first, you may be excluded from eligibility. The procedures differ by program.
Please confirm the order of procedures before signing a contract and starting construction, as it varies by program.
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 method of securing differs depending on the construction method, and when securing brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten is a specialized exterior remodeling company strong in roofing work, so we will check the condition of the roof before installation, and if deterioration is advanced, we will also propose methods such as roof overlay (cover method) or re-roofing before installation.
The roof is old. Should I do roof remodeling 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 an on-site inspection!
Is it better to install a storage battery together with solar panels?
If you want to use the generated electricity at night or prepare for power outages, simultaneous installation is recommended. The selling price for electricity will be 8.3 yen/kWh after the fifth year, making it more advantageous to use it in your home rather than selling it.
Additionally, the subsidy in Kanagawa Prefecture requires the simultaneous introduction of solar panels and storage batteries. Please check the official page of Oiso Town for the conditions for each facility. You can compare “solar only” and “solar + storage battery” through a financial simulation.
How many kW can be installed on my roof? Is it okay for north-facing roofs or roofs with shadows?
The capacity that can be installed varies depending on the shape, orientation, and size of the roof. At Kakeru Koumuten, we create a layout diagram based on the drawings and on-site inspection, 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 shadows cast by neighboring houses, trees, and slopes differ from one house to another. 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 and installation capacity of the roof.
Additionally, please note that separate time is required for applications for subsidies and power companies, so please consult us early.
What is the current selling price (FIT)?
For residential use (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 in the 2026 fiscal year.
The idea is to recover the initial costs quickly in the first 4 years and then focus on self-consumption. Kakeru Koumuten provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-service maintenance notices via DM and visits customers who wish to have inspections. We can also clean solar panels with a special brush if the power generation decreases 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 handle renovations for roofs that already have solar panels installed?
Yes, we can. Kakeru Koumuten can remove and reinstall solar panels in-house, allowing us to remove the panels, perform roof overlay (cover method) or re-roofing, and then reinstall them all in one process. The removed panels can be stored in our own warehouse.
For information on costs, please see the solar panel removal and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Nakagun (Oiso Town and Ninomiya Town), please consult Kakeru Koumuten
Our company handles a wide range of exterior renovations, including solar panels, roof work, and wall work in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture.
We receive many requests from customers, including renovation companies and real estate agencies!
Kakeru Koumuten promises “high-quality renovations at low costs”, and we have received great feedback from numerous customers.
We continue to update our annual construction performance, 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 cover installation for walls.
We are also happy to assist with small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide temporary measures without setting up scaffolding, as long as safety can be ensured, so please consult us!
“I want to know about recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide the best 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 optimal construction plan!
We are confident that we will not lose in terms of cost, quality, and planning compared to other companies for exterior work!
We are confident, so we welcome competitive quotes!
Estimates are completely free, and if our company is inferior to others, you are free to decline!
Characteristics of Nakagun (Oiso Town and Ninomiya Town) and Points for Solar Work
Nakagun 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 plateau, such as Mount Komayama and Mount Takatō, to the north, with 65% of the town occupied by hilly areas, while the urban area is formed on the flat land along National Route 1. According to the official page of Ninomiya Town, 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, bordered by the Tanzawa mountain range to the north, and adjacent to Odawara City across the Nakamura River (Oshikiri River) to the west.
Below are the characteristics of Nakagun (Oiso Town and Ninomiya Town) and points to consider when installing solar panels and storage batteries. (Tap to open)
View the characteristics of Nakagun (Oiso Town and Ninomiya Town) and points for solar work
■ Two Towns Facing Sagami Bay. Consideration for Sea Breeze in Coastal Homes
Oiso Town and Ninomiya Town both face Sagami Bay to the south. In coastal areas, the salt in the sea breeze can affect the metal fittings and equipment around the roof. It is important to choose panels, frames, fittings, and equipment such as power conditioners that are suitable for your location, based on the installation conditions specified by the manufacturer (distance from the coast and salt-resistant specifications, etc.).
■ From Flat Areas to Hilly Regions. Check the Shadows Cast by Slopes and Vegetation
Oiso Town is 65% hilly, and the northern part of Ninomiya Town is backed by the Tanzawa Mountains. In flat residential areas, shadows from neighboring houses and utility poles are predominant, but in homes closer to hilly areas, shadows from slopes and surrounding trees may change sunlight exposure in the morning and evening. Kakeru Koumuten Co., Ltd. creates layout diagrams based on blueprints and site conditions, allowing you to confirm through power generation simulations.
■ Roofs That Accumulate Leaves and Branches Should Consider Ease of Cleaning
In residential areas close to hills with many trees, leaves and branches may easily accumulate on panels and rain gutters. If dirt such as 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 the rain gutters.
■ In Lowlands Near Rivers and the Sea, Confirm the Installation Location of Equipment
The western side of Ninomiya Town borders Odawara City across the Nakamura River (Oshikiri River). In lowlands near rivers and the sea, the risk of flooding may vary depending on your location. When deciding on the installation location for batteries and power conditioners, it is reassuring to check the flooding risk for your location on a hazard map.
■ Different Subsidies by Town. Oiso Town Has Its Own System, While Ninomiya Town Provides Information on Prefectural Joint Purchase Projects
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 batteries, as stated on the official town page, and introduces Kanagawa Prefecture’s joint purchase project. It is important to check the systems in your town in advance, in conjunction with the timing of the construction.
■ Check the Roof Condition According to the Age of the Building
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.
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 about any urgent issues!
Service Area in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo.
List of Areas in Nakagun (Oiso Town and Ninomiya Town), Kanagawa Prefecture
List of Areas in Oiso Town
Oiso Town Ikisawa/Oiso Town Ishigamidai/Oiso Town Oiso/Oiso Town Getsukyo/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 key points!
・Top 12 solar power generation manufacturers! Features and selection points are also introduced!
・What are the installation costs for solar power generation? Thorough explanation of 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!
