Leave Your Solar Panel Installation Work in Nishi, Yokohama City to Kakeru Koumuten Co., Ltd.!
For Solar Panel and Storage Battery Installation in
Nishi Ward, Yokohama,
trust Kakeru Koumuten Co., Ltd.!
Kakeru Koumuten Co., Ltd. is a company specializing in exterior renovations based in Yokohama.
As a company strong in roofing work, we are entrusted withsolar panel and storage battery installations considering roofs and waterproofing!
“How to Choose a Solar Panel Contractor in Nishi Ward”
“Costs for Solar Panel and Storage Battery Installation”
“Subsidies Available for Solar System Installation in Nishi Ward”
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 Nishi Ward, Yokohama
- Roof Inspection Before Installing Solar Panels
- Possible Subsidies and Grants Available in Nishi Ward
- Price List for Solar Panel and Storage Battery Installation
- Breakdown of Installation Capacity, Equipment, and Construction Costs
- Self-Estimate and Profit Simulation for Solar Power Generation
- Customer Testimonials
- Case Studies of Solar Panel Installations
- How to Choose a Solar Panel Installer in Nishi Ward, Yokohama
- Benefits of Introducing Solar Equipment
- Points to Consider When Introducing Solar Power Generation
- How to Choose Solar Panels
- Frequently Asked Questions About Solar and Storage Battery Installation in Nishi Ward
- If You Are Looking for a Solar Panel Installer in Nishi Ward, Contact Kakeru Koumuten
- Characteristics of Nishi Ward, Yokohama and Key Points for Solar Installation
- Service Area in Nishi Ward, Yokohama
Reasons Why Kakeru Koumuten is Chosen for Solar Panel Installation in Nishi Ward, Yokohama
Regarding why our company is entrusted with solar panel installation by customers in Nishi Ward, Yokohama,
we have unique strengths in solar panel installation that cannot be imitated by other companies,
which have received high praise from many customers.
so we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome estimates from any number of companies!
1. We Also Handle Exterior Renovations Beyond Solar Panel Installation!
Problems such as leaks caused by solar panel installation may arise from insufficient checks on the roof and waterproofing at the installation site.
Even if one is knowledgeable about solar panels, there are cases where the roof and waterproofing at the installation site are outside their expertise, so caution is necessary.
It is reassuring to have expertise in roofing to avoid maintenance issues and troubles after installation!
Kakeru Koumuten Co., Ltd. is strong in roofing work and can also detach and attach solar panels in-house, allowing for quick responses to maintenance and urgent troubles after solar panel installation!
2.Equipment Specialized for Exterior Renovation
Kakeru Koumuten Co., Ltd. has organized the following warehouses and material storage areas to provide low-cost, high-quality solar construction and exterior renovations.
We have established five bases centered around 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 scaffolding materials necessary for temporary scaffolding based on construction conditions and can assemble scaffolding in-house.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can also cut costs related to scaffolding work.
We own scaffolding materials for approximately 50 detached houses!
Even in cases where there are elevation differences on the site, our in-house scaffolding team will plan the 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, allowing us torespond quickly in emergencies!
Sorting and Transporting Waste Materials In-House
The installation of solar panels often involves roofing work, generating various waste materials such as paint, wood, and metal.
By sorting and recycling waste materials, we can significantly cut waste disposal costs.
Exterior Remodeling Dedicated Showroom
In the showroom, not only can you have meetings, but you can also
check the actual foundation brackets for solar panels and see how they are installed on roofing materials!
We can also provide simulations of potential earnings and installation costs when introducing solar panels!
Since roofing and exterior wall work often accompany each other, we also have samples of roofing materials and models that explain the structure, allowing us to provide detailed explanations!
3.All Work Performed by Our Own Team
One of Kakeru Koumuten’s major strengths is its complete in-house construction.
By having a consistent system from inquiry to project completion, Kakeru Koumuten can provide high-quality roof renovations 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 the construction management representative, smooth communication is possible.
We can provide consistent in-house construction from temporary scaffolding installation, exterior wall painting, to roof renovations!
4. Various Permits and Skilled Workers
We have obtained construction industry 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 roof projects for factories and other facilities!
5. Warranty and Aftercare
In addition to the manufacturer’s warranty for solar panel installation, we also provide our own construction warranty (leakage warranty)!
(The construction warranty for solar panel installation is 10 years. Depending on the condition of the roof before installation, we may not be able to provide a warranty unless roof renovations are performed. The construction warranty is separate from the manufacturer’s product warranty, and the scope and conditions vary depending on the warranty details.)
Aftercare is available annually, and we send out notification DM each year.
If you have any questions about the warranty, please click on the image above!
6. Flexible and Prompt Response
Our company is equipped to handle various roofing troubles and situations.
If you cannot access the roof at high altitudes, we can utilize a drone to assist!
During leak investigations, we can also conduct surveys using a thermal imaging camera.
If the power generation of the solar panels decreases due to dirt, we can also 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
Kakeru Koumuten provides “estimates,” “layout diagrams,” “power generation simulations,” as well as “solar construction guidebooks” and “profit and loss simulations” that take into account loan interest rates and electricity costs.
The profit and loss simulation can be created for projected cumulative profits and losses over 20 to 30 years.
For customers who are not familiar with solar construction, we compile easy-to-understand materials that include points to consider and disadvantages!
We encourage you to obtain comparative estimates and compare them with other companies’ plans!
Roof Inspection Before Installing Solar Panels
Once solar panels are installed, they will remain on the roof for 20 or 30 years.
Confirming “Is it okay to install them directly on the current roof?” before installation is the key point to prevent leaks and unnecessary expenses!
Kakeru Koumuten, which specializes in roofing work, has summarized the items to check before installation.
| 1. Types of Roofing Materials and Age | The fixing method varies depending on the roofing materials such as slate, tiles, metal roofs, and flat roofs (rooftop waterproofing). If the remaining lifespan of the roofing materials is short, we may suggest roof renovation first. |
| 2. Condition of Substrate and Waterproof Sheet | If the underlayment or roofing (waterproof sheet) beneath the roofing materials 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 confirm it with a power generation simulation. |
| 4. Shape of the Roof and Usable Area | The number of panels (installation capacity) that can be placed depends on the shape and size of the roof. The number of panels that can be installed varies depending on the panel size, so we will compare based on the total output of the roof. |
| 5. Fixing Method and Waterproofing Details | We will check whether the method involves drilling holes in the roofing materials for fixing or using brackets to secure the roofing materials. The fixing method varies by technique, so please confirm the waterproofing treatment method for the fixed parts during the estimate. |
| 6. Weight of the Roof | The roof will become heavier due to the panels being added. After investigating the existing roof, substrate, and load-bearing capacity, switching to lighter roofing materials may also be an option if necessary. |
| 7. Installation Location of Equipment and Wiring | We will confirm the installation locations for the power conditioner and storage battery, as well as the wiring route to the distribution board. The length of the wiring will also affect costs. |
| 8. Ease of Scaffolding Setup and Delivery Routes | If there are elevation differences on the site, planning for scaffolding and delivery routes for equipment and materials may require some ingenuity. The width of the front road and any steps on the site will also be checked during the site survey. |
Fixing Methods and Checkpoints by Roofing Material
| Roof Material | Main Fixing Method | Pre-Installation Check Points |
|---|---|---|
| Slate Roof | Varies by method (e.g., fixing brackets to the roof material and substrate with screws) | Waterproof treatment of fixing parts, cracks or deterioration of slate, condition of 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/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 perform roof renovations 10 to 20 years after installation, there will be additional costs for removing and reinstalling 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 Nishi Ward, Yokohama City
PossibleSubsidies and Grants in Nishi Ward, Yokohama City, Kanagawa Prefecture
If you are introducing solar panels or storage batteries in Nishi Ward, there may be programs from the “National Government,” “Kanagawa Prefecture,” and “Yokohama City” that are applicable.
The following information is based on the official pages of each program as of October 6, 2026. The acceptance status may change depending on the budget, so please check the latest information before contracting or starting work.
Eligibility Conditions and Application Period for Subsidy Programs
| Program | Main Eligibility Conditions | Subsidy Amount | Application Period & Status |
|---|---|---|---|
| Yokohama City “Yokohama Green Energy Partnership Project (YGrEP)” Fiscal Year 2026 | Yokohama residents installing eligible equipment at their homes. Solar power must be newly installed, and either a storage battery, eco-cute, electric vehicle, etc., must be installed simultaneously or already installed. | Solar power: 15,000 JPY/kW (up to 4 kW) Storage battery: 120,000 JPY per case (Refunds via cashless points, etc.) |
Participation & Installation Support Application: June 15, 2026 – December 25, 2026 (Application must be made before installation) Installation Completion Application: By January 22, 2027 Ends once the budget limit is reached |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Residential Solar Power Generation and Storage Battery Installation Subsidy” | Installation of solar power generation and storage systems together in residential buildings (with seismic performance ensured). Applications must be made by the individual, and construction can begin after grant approval. | Solar power: 70,000 JPY/kW Storage battery: 150,000 JPY per unit |
Phase 1: May 11, 2026 – June 30, 2026 Phase 2: Starts September 7, 2026 (first-come, first-served) As of September 7, 2026, the application amount has reached the budget limit, and applications are closed. Please check the prefecture’s official page for future recruitment. |
| National “DR Home Storage Battery Project” (Fiscal Year 2025 Supplement) | New installation of registered home storage systems that can be utilized for DR (demand response). | Calculated based on an initial effective capacity of 1 kWh at 34,500 JPY (subsidy rate within 30% & maximum 600,000 JPY per application). | As of May 29, 2026, the budget has been reached, and public recruitment has ended (the official site states there are no plans to reopen applications, and currently, applications cannot be made). |
| National “Mirai Eco Housing 2026 Project” (Renovation) | Storage batteries are one of the eligible installations, 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 equipment. | Storage battery: 96,000 JPY per unit | Ends once the budget limit is reached. As of October 5, 2026, the application amount for renovations is displayed as 8% of the budget on the official site. Please check the official site for application status. |
| Yokohama City “Solar Power Generation Installation Support Subsidy” | Small and medium-sized enterprises and sole proprietors in Yokohama City (residential applications are not eligible). There are conditions for the target individuals and equipment, such as being self-consumption type equipment. | Solar power + storage system: 100,000 JPY/kW (up to 5,000,000 JPY) Solar power only: 80,000 JPY/kW (up to 4,000,000 JPY) |
May 1, 2026 – October 30, 2026, 17:00 (first-come, first-served until the budget limit is reached). As of September 7, the application amount has reached 70% of the budget amount. |
| Kanagawa Prefecture “Fiscal Year 2026 Kanagawa Prefecture Self-Consumption Type Renewable Energy Installation Subsidy” | Corporations and sole proprietors filing blue returns（Personal residences are not eligible). Solar power must have a generation output of 10kW or more, facilities for business use, equipment not certified under FIT/FIP, etc. | Solar Power: 80,000 JPY/kW, etc. Storage System: 50,000 JPY/kWh (maximum 5,000,000 JPY) |
Application closed on September 3, 2026 (when the application amount reached the budget) |
YGrEP requires a “Participation and Introduction Support Application” before installation, while Kanagawa Prefecture’s residential subsidies require not only application acceptance but also construction to commence after receiving “Grant Decision”. If you start installation or work beforehand, you will be ineligible. The prefectural residential subsidies are granted after completion of work and submission of performance reports and reviews. The order of procedures varies by system, and applying does not guarantee a grant, so please confirm before contracting or starting work.
At Kakeru Koumuten Co., Ltd., we will guide you on eligibility conditions and business requirements for each system after confirming them.
National Subsidy “DR Home Battery Project (Support Project for the Introduction of Home Storage Systems for DR Resource Implementation)”
The national government has been implementing the “DR Home Battery Project” to support the installation of home storage batteries.
This project targets those who are introducing new 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 1kWh, with a subsidy rate of up to 30% and a maximum of 600,000 JPY per application. There are conditions such as being ineligible for items contracted or ordered before the grant decision.
However, the fiscal year 2025 supplementary budget application amount reached the budget on May 29, 2026, and the public recruitment has ended. The official site also states that there are no plans to reopen public recruitment, and applications are currently not possible. Please check the official site 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 Residential Solar Power and Storage Battery Installation Subsidy”
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 1kW of solar power generation output and 150,000 JPY per storage system.
For example, if you install a 4kW solar panel and one storage battery, the subsidy amount would be calculated as 4kW × 70,000 JPY + 150,000 JPY = 430,000 JPY.
Eligibility requires the home to have seismic performance, the storage system to be a registered product, and if construction begins before the grant decision, it will be ineligible. The application must be made by the individual (applications by the construction contractor are not allowed), and it is also possible to combine this with Yokohama City’s YGrEP.
For the fiscal year 2026, applications for the first phase (May 11 to June 30) and the second phase (starting September 7, first-come-first-served) were accepted. The second phase has been closed as of September 7, 2026, when the application amount reached the budget amount. Please check the official Kanagawa Prefecture page for future recruitment.
👉 Click here for the official Kanagawa Prefecture page
Kanagawa Prefecture “Subsidy for Introducing Self-Consumption Type Renewable Energy for Fiscal Year 2026” (for businesses)
Kanagawa Prefecture is also implementing a subsidy for businesses that introduce “self-consumption type” facilities that use electricity generated by solar panels.
Eligible applicants are corporations or individual business owners filing blue returns, and individual residential installations are not eligible.
Conditions include that the solar power generation must have an output of 10kW or more and supply electricity to business facilities within the prefecture, and that the equipment must not be certified under FIT or FIP.
The subsidy amount is 80,000 yen per kW for solar power generation and 50,000 yen per kWh for the accompanying storage system (with a maximum of 5 million yen).
As the application amount reached the budget amount for fiscal year 2026, recruitment was closed on September 3, 2026.
Businesses considering the installation of solar panels on commercial buildings in Nishi Ward should check the official Kanagawa Prefecture page for the next recruitment.
👉 Click here for details
Yokohama City “Subsidy for Introducing Solar Power Generation” (for businesses)
Yokohama City is implementing a system to subsidize part of the introduction costs for small and medium-sized enterprises and individual business owners within the city for solar power generation equipment and other installations.
Residential solar power generation is not eligible, and for households, the YGrEP below will be the point of contact. Businesses installing solar panels on stores, offices, factories, etc., in Nishi Ward may have the possibility to utilize this, but merely conducting business from home does not guarantee eligibility. It is necessary to confirm the requirements for small and medium-sized enterprises and individual business owners, as well as the condition that the equipment must be self-consumption type (equipment for selling electricity is not eligible).
The subsidy amount is 100,000 yen per kW when introducing both solar power generation and storage systems simultaneously (maximum of 5 million yen), and 80,000 yen per kW for solar power generation only (maximum of 4 million yen).
The application period for fiscal year 2026 is from May 1, 2026, to October 30, 2026, at 5 PM, and applications are accepted on a first-come-first-served basis until the budget limit is reached. As of September 7, it has been announced that the application amount has reached 70% of the budget amount, so early confirmation is recommended. Installation of equipment and commencement of construction must take place after the grant decision date.
For detailed conditions and application methods, please check the official website of Yokohama City.
👉 Click here for the official Yokohama City page
Yokohama City “Reiwa 8 Year Yokohama Green Energy Partnership Project (YGrEP)”
Yokohama Green Energy Partnership (YGrEP) is a project aimed at realizing a decarbonized society.
In Yokohama City, households that participate in YGrEP and install eligible equipment (refer to the eligible equipment below) will receive cashless points and other rewards. Residents of Nishi Ward are also eligible.
◎ Eligible Equipment and Reward Amounts ◎
● Solar Power Generation Equipment (new installation): 15,000 JPY/kW (up to 4kW)
* It is a condition to install or have already installed either a storage battery, eco-cute, or electric vehicle simultaneously.
● Storage Battery: 120,000 JPY per unit
● Eco-Cute: 20,000 JPY per unit
● Electric Vehicle/Plug-in Hybrid Vehicle (set with solar power generation equipment): 100,000 JPY per unit
* It is a condition to install or have already installed solar power generation equipment simultaneously.
● Electric Vehicle alone (without solar power generation equipment): 50,000 JPY per unit
● Fuel Cell (Enefarm): 30,000 JPY per unit
● Solar Heat Utilization System: 50,000 JPY per unit
● V2H Charging and Discharging Equipment: 100,000 JPY per unit
For example, if you install a 4kW solar panel and a storage battery simultaneously, the calculation for the reward amount will be 60,000 JPY for solar power + 120,000 JPY for storage battery = a total of 180,000 JPY.
The application process is “Participation and Installation Support Application (before installation) → Installation of equipment → Completion Application”, and equipment installed before the installation support application is not eligible. The participation and installation support application for Reiwa 8 Year will be from June 15, 2026, to December 25, 2026, and the completion application will be until January 22, 2027, and will end once the budget limit is reached.
If selling electricity, it must only be for the surplus that cannot be used at home, and submission of monitoring data such as power generation amounts about once a year is also a condition. Additionally, only V2H charging and discharging equipment is eligible for rewards for businesses.
For information on application methods, combining with national and Kanagawa Prefecture subsidy projects, and point rewards, please check and contact us from this special site.
Solar Panel Installation and Storage Battery Installation Price List
⇧Service Menu | For Costs Related to Solar Panel and Battery Installation, Click Here
⇧Service Menu | For Costs Related to Solar Panel Removal and Water Heater Removal, Click Here
Breakdown of Installation Capacity, Equipment, and Construction Costs
The costs for solar panels and batteries should be confirmed by separating them into “Equipment Costs (Device Costs)” and “Construction Costs.”
Even for the same “Complete Solar Panel Installation,” the amount can vary significantly depending on the installation capacity, equipment grade, and roof condition.
Understanding Installation Capacity (kW) and Battery Capacity (kWh)
The installation capacity of solar panels is determined by “Output of One Panel (W) × Number of Panels”, with the unit being kW (kilowatt). Batteries are compared based on the amount of electricity they can store, expressed in kWh (kilowatt-hour).
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 panels as approximately 800,000 JPY to 1,200,000 JPY for 3 to 5 kW, and 1,200,000 JPY to 1,900,000 JPY for 6 to 10 kW. (These are just estimated amounts and may vary based on factors such as wiring length, scaffolding range, existing roofing materials, and panel layout.)
▶ Installation Menu | Costs for Solar Panel Installation and Battery Installation
Items to Check on the Quotation (Cost Confirmation)
When comparing prices in competitive quotations, it is common to compare different capacities and equipment. Please check if the following items are clearly stated in each company’s quotation!
| 1. Solar Panels | Manufacturer, model number, output per panel (W), number of panels, total installation capacity (kW) are written. |
| 2. Power Conditioner | Manufacturer, model number, capacity, number of units, installation location (indoor/outdoor). Also check if it is a type that controls the battery together. |
| 3. Battery | Manufacturer, model number, capacity (kWh), range usable during power outages (whole house or specific circuits), installation location. |
| 4. Mounting Frame and Fittings | Name of fittings suitable for roofing materials and fixing methods (whether it is a method that drills holes or a method that clamps and fixes). |
| 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 waterproof treatment at fixing points, whether necessary roof repairs and substrate reinforcements are included. |
| 7. Applications | How much support is included for applications to the power company, certification applications 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-included or tax-excluded, conditions under which additional costs may arise, and the contents and duration of manufacturer warranties and workmanship warranties. |
If the capacities differ, both the price and power generation will change. Kakeru Koumuten Co., Ltd. welcome competitive quotations, so if you bring quotations from other companies, we will explain the differences for each item!
Self-Quotation and Profit and Loss Simulator for Solar Power Generation
With the simulator above,
you can get an approximate estimate and income simulation for 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 an approximate estimate and income simulation!
*The simulation results are approximate. Actual income may vary depending 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)!
Examples of Solar Panel Installation
| Construction Details |
| Solar Panel Installation Battery Installation |
| Existing Roofing Material |
| Horizontal Metal Roof (Super Galtect) |
| Installation Capacity |
| Solar Panel: 4.3kW Battery: 5kWh |
| Base Mounting Hardware Used |
| Niigata Manufacturing/Aluminum Catch Type Hardware |
| Fixing Method & Waterproofing Arrangement |
| Fixed by catching the horizontal metal roof with catch type hardware (Catch Method) |
| Price Range |
| 2,200,000 JPY – 2,300,000 JPY *Due to the grant being provided, the actual burden amount is approximately 1,000,000 JPY Estimated recovery period for construction costs: about 8-9 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 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 configuration 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 Nishi Ward, Yokohama City
There are many solar panel installation contractors available in Nishi Ward, Yokohama, and you may be unsure which contractor to choose.
Therefore, when requesting solar panel installation and battery storage installation work, let’s confirm the following four points.
● Have extensive knowledge not only about solar panels but also about roofs
● Confirm the presence of warranties and aftercare services
● Obtain estimates from multiple contractors (three companies is a guideline)
● Check if they provide support for subsidy applications
By confirming the above four points, you will be able to choose a reliable contractor.
Have knowledge not only about solar panels but also about roofs
Defective installation of solar panels can sometimes be caused by a lack of knowledge and verification regarding roofs and waterproofing.
While knowledge about solar panels is certainly important, understanding the roof and waterproofing at the installation site of the solar panels is also crucial.
⚠︎Examples of troubles caused by insufficient verification of roofs and waterproofing
・Solar panels were installed on a deteriorated roof, leading to leaks
・Solar panels were installed on a roof with a short lifespan, requiring a remodel to detach and reattach the solar panels within a few years
・Misjudgment of the type of waterproofing led to incorrect treatment 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 presence of warranties and aftercare services
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, disclaimers, and cost conditions.
Solar panels and battery storage units come with manufacturer warranties, but also confirm whether there is a workmanship warranty in case of leaks after installation!
For contractors that offer a workmanship warranty, if leaks occur after installation within the warranty period and conditions, they may cover the repairs under the warranty.
Additionally, some contractors provide aftercare services separate from warranties, so be sure to check if the contractor you are considering has aftercare services.
Since abnormalities or damages on the roof may not be visible, you might not notice them yourself.
By conducting inspections of hidden areas during aftercare, you can more easily detect abnormalities early and prevent major repairs or failures!
At Kakeru Koumuten Co., Ltd., the installation of solar panels comes with a leak warranty as part of the workmanship warranty. (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 aftercare maintenance and send out annual DM!
After checking the DM, if you wish, we will visit for aftercare maintenance!
Obtain estimates from multiple contractors (3 companies as a guideline)
When requesting solar panel installation, let’s 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 your preferred contractor at a lower price, we recommend obtaining estimates from multiple contractors.
When comparing estimates, please check:
“Check the estimate items”
“Type of solar panel”
“Warranties and after-sales services”
and make a detailed comparison! Avoid judging solely based on cost, as using lower-grade materials or skipping processes can reduce costs!
▶ Go to “Breakdown of installation capacity, equipment, and 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 you make mistakes in the order of procedures or have deficiencies in documents, you may not receive the grant.
For systems like Kanagawa Prefecture’s housing subsidies, where contractors cannot apply on your behalf and you must apply yourself, 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 grant approval) before proceeding with the construction!
For the prefectural housing subsidy, after the construction is completed, you will need to report the results and go through a review process to receive the grant! (The flow of procedures varies by system)
▶ Go to “Subsidies and grants that may be applicable in Nishi Ward” in this article
Benefits of Introducing Solar Equipment
The benefits of introducing solar panels are as follows!
Benefit 1: Economic Benefits
The biggest advantage of introducing solar panels is the economic benefit!
The selling price of electricity has decreased compared to ten years ago, but by consuming the generated electricity, you can reduce the amount of electricity purchased from the utility company and gain benefits!
As electricity costs rise, the ability to cover your consumption with solar power becomes attractive!
If you plan to use the generated electricity at night, installing a storage battery is essential!
Furthermore, the selling price (FIT) for residential use (under 10kW) will be set at “24 yen/kWh for the first four years, and 8.3 yen/kWh from the fifth to the tenth year” for certifications after October 2025, and the same price will apply for the 2026 fiscal year. After the fifth year, it is often more advantageous to use it at home (self-consume) rather than sell it, so combining it with a storage battery is also an option.
👉 For purchase prices and periods, visit the Agency for Natural Resources and Energy
Advantage 2 Subsidies can be utilized!
Subsidy conditions and amounts vary by prefecture and municipality, but if you meet the conditions, you may be able to utilize subsidies!
Reducing the actual burden through subsidies is a significant advantage!
In Nishi Ward, you may be eligible for subsidies from Yokohama City’s YGrEP or Kanagawa Prefecture.
Advantage 3 Environmentally friendly!
Solar power generation has low carbon dioxide emissions and can reduce dependence on fossil fuels, contributing to the mitigation of global warming.
Solar panels themselves do not produce noise or exhaust gases during the generation process, making them an environmentally friendly method of power generation. (However, devices like power conditioners do have operational noise.)
Advantage 4 Heat insulation effects can be expected!!
By installing panels on the roof or rooftop, they block direct sunlight from hitting the roof.
Especially in summer, this can help reduce the temperature of the roof, providing a heat insulation effect!
（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 capability, 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 particularly overlooked maintenance cost is for the roof where solar panels are installed.
If you perform roof renovations 10 to 20 years later, there will be costs for removing and reattaching the solar panels.
If the existing roof is deteriorating, it is reassuring to renovate it with durable roofing materials before installing solar panels!
Additionally, there will be costs for regular inspections of the equipment, repairs or replacements of the power conditioner, and updates due to the deterioration of the storage battery.
It is reassuring to be able to request a simulation considering 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 of the fixed areas 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, one option is to replace the roofing material with a metal roof and fix the solar panels using the catch method. （The catch method has compatibility conditions between the roofing material and brackets, and it cannot be used with all metal roofs）
Catch-type base hardware 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, replacing it with a lighter roof may also be an option if necessary.
How to Choose Solar Panels?
There are many manufacturers of solar panels, and their output and costs vary.
It is not simply a matter of “this manufacturer has the best solar panels”; it is important to choose solar panels that are suitable for your life plan and building!
Here are some points to consider when comparing solar panels!
Choosing Method 1: Compare based on total output of the roof
When installing solar panels on the roof, it is important to know how much electricity can be generated in a limited area, and the more electricity generated, the better!
The size and output of solar panels vary by manufacturer.
A panel with an output of 350W and a panel with an output of 400W may seem like the higher output panel is better at first glance.
However, if the size of the panel does not fit well with the roof, “20 panels of 350W can be installed,” while “15 panels of 400W can be installed,” meaning the number of panels that can be installed on the same roof differs due to the size of the panels.
400W×15 panels = 6kW (total output of the roof)
350W×20 panels = 7kW (total output of the roof)
As shown above, even if the output of a single panel is lower, the total output of the roof may be higher!
It is important to consider the total output of the roof rather than the output of a single panel!
*The above is the calculation of total output (kW). The actual electricity generation amount (kWh) will vary depending on conditions such as the roof’s orientation, slope, and shading.
Choosing Method 2: Compare based on degradation rate of solar panels
Solar panels have a degradation rate, and their output gradually decreases after 10 years and 20 years.
The degree of output reduction after long-term use varies by product. The manufacturer’s output guarantee value is a standard figure for the warranty and does not indicate the actual degradation rate or the amount of electricity generated.
Choosing solar panels by considering the degradation rate as well as the initial output will help you avoid regrets!
Choosing Method 3: Compare based on warranty period
There are several types of warranties for solar panels, including “output warranty,” “natural disaster warranty,” and “system warranty,” and the warranty periods vary by manufacturer.
For output warranties, some manufacturers offer a 30-year warranty while others provide a 10-year warranty, so it varies widely!
It’s always better to have a longer warranty, so let’s check the warranty periods and conditions of the manufacturers you are considering!
Frequently Asked Questions about Solar Power and Storage Battery Installation in Nishi Ward
We have compiled frequently asked questions from customers considering the installation of solar panels and storage batteries in Nishi Ward. (Tap to open the answers)
How much does it cost to install solar panels and storage batteries in Nishi Ward, Yokohama City?
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.
For cost estimates by capacity, please refer to the solar panel installation and storage battery installation pricing page. We will create a layout diagram from the drawings and on-site survey and provide a free estimate!
Are there any subsidies available for solar power and storage battery installation in Nishi Ward?
As of October 6, 2026, the application period for Yokohama City’s YGrEP (15,000 yen/kW for solar power, up to 4kW; 120,000 yen per storage battery) is ongoing (it will end once the budget limit is reached). The Kanagawa Prefecture subsidy (70,000 yen/kW for solar power; 150,000 yen per storage battery) reached its budget limit on September 7 for the second phase of Reiwa 8, and the national DR home storage battery project has ended its public recruitment.
Since the application status may change, please check the subsidy and grant section and consult with us before signing a contract.
Can I apply for subsidies after the construction is completed?
For many programs, procedures must be completed before construction. Yokohama City’s YGrEP requires “participation and introduction support application” before installation, and Kanagawa Prefecture’s subsidy requires “construction to start after grant decision,” so if you install first, you will be ineligible.
The order of procedures varies by program, so please confirm before signing a contract or starting construction.
Can solar panels be installed on a slate roof? I’m worried about leaks.
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 when fixing brackets to the roofing material or substrate, waterproofing treatment of the fixed parts is essential.
Kakeru Koumuten is a specialized exterior renovation company strong in roofing work, so we will check the condition of the roof before installation, and if deterioration is advanced, we can also propose methods such as roof overlay (cover method) or replacement before installation.
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 after 10 to 20 years of installation, the cost of removing and reinstalling solar panels will be incurred separately. If the remaining lifespan of the roof is short, it may be more cost-effective to renovate with durable roofing materials before installation.
Please consult us on how to proceed with the installation after confirming the condition of the roof through a site survey!
Is it better to install a storage battery together with solar panels?
For those who want to use generated electricity at night or prepare for power outages, simultaneous installation is recommended. Since the selling price of electricity will be 8.3 yen/kWh after the fifth year, it is often more advantageous to use it at home rather than sell it.
Additionally, Kanagawa Prefecture’s subsidies require the simultaneous introduction of solar panels and storage batteries, and Yokohama City’s YGrEP also has conditions for combinations with storage batteries. 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 from the drawings and site survey, and provide you with the installation capacity and power generation simulation.
In Nishi Ward, due to densely populated residential areas and hilly southern regions, the shading caused by surrounding buildings, trees, and elevation differences varies for each house. You can check the expected power generation through the power generation simulation.
How long does the construction period take?
In the above construction example (solar panels 4.3 kW + storage battery), it took about 3 days. The duration may vary if roof work is done simultaneously or depending on the roof shape and installation capacity.
Please note that additional time is required for applications for subsidies and electric companies, so please consult us early.
What is the current selling price (FIT) for electricity?
For residential use (under 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, with the same price applied for the 2026 fiscal year.
The idea is to recover initial costs more quickly in the first four years, and then focus on self-consumption. Kakeru Koumuten provides a financial simulation that takes into account loan interest rates and electricity costs.
Can you handle maintenance and inspections after installation?
Yes, we can. Kakeru Koumuten sends out annual after-maintenance notices via DM and visits customers who wish for inspections. We can also clean solar panels using specialized brushes if the power generation decreases due to dirt.
Since it is difficult to check areas on the roof by yourself, please feel free to consult us if you have any concerns.
Can you also renovate 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 consistently. The removed panels can be stored in our warehouse.
For costs, please refer to the solar panel removal and water heater removal pricing page.
If you are looking for a solar panel installation contractor in Nishi Ward, please consult Kakeru Koumuten
Our company handles many exterior renovations, including solar panels, roof work, and exterior wall work in Nishi Ward, Yokohama City.
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 numerous customers.
We continue to update our construction performance 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 installations.
We are also happy to handle small jobs such as partial repairs and rain gutter cleaning!
In urgent cases such as leak repairs, we may be able to provide emergency measures without setting up scaffolding, as long as safety can be ensured, so please consult us!
“I want to know about recommended solar panels”, “I want to keep costs down as much as possible”, “I just want an estimate for now”, we will provide 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 best construction plan!
We are confident that we will not be outdone by other companies in terms of cost, quality, and planning for exterior work!
We are confident, so we welcome comparative estimates!
Estimates are completely free, and if our company is inferior to others, you are free to decline!
Characteristics of Nishi Ward, Yokohama City and Points for Solar Work
Nishi Ward, Yokohama City, is located almost in the center of Yokohama City, with an area of 7.03 km2, making it the smallest ward among the 18 wards in the city. It is an area where the historical and downtown atmosphere since the opening of the port coexists with urban areas such as around Yokohama Station and the Minato Mirai 21 district! We have summarized the topography and housing situation of Nishi Ward and points to consider when installing solar panels and storage batteries below. (Tap to open)
View the characteristics of Nishi Ward, Yokohama City and points for solar work
■ Existing urban areas and urban centers coexist, resulting in different conditions for building shadows and roof areas
Nishi Ward is the smallest in both area and population among the 18 wards, but it is noted for the coexistence of established urban areas and the city center around Yokohama Station and the Minato Mirai 21 district. The ward consists of residential areas in the north, areas with a traditional downtown atmosphere in the south (such as Asama-cho, Hiratsuka, and Fujidana-cho), and the Minato Mirai 21 district, which is under development on reclaimed land (Nishi Ward materials).
In densely populated areas, the shadows from neighboring houses and the number of panels that can be installed on roofs (installation capacity) vary from house to house. Kakeru Koumuten Co., Ltd. creates layout diagrams based on blueprints and site conditions, and you can check the power generation simulation.
■ In the hilly southern area, confirming scaffolding and delivery routes is essential
According to the Nishi Ward materials, the highest point in the ward is 55.8m above sea level in Motokubo-cho, and it is noted that the southern area has many hills and densely packed houses. In places with slopes and differences in elevation, careful planning of scaffolding and delivery routes for equipment and materials may be necessary. Kakeru Koumuten Co., Ltd. will respond according to the site with our own scaffolding team and scaffolding materials.
■ Yokohama’s annual sunshine hours are about 2,018 hours
According to the Japan Meteorological Agency’s average values (1991-2020), Yokohama’s annual sunshine hours are about 2,018 hours. Monthly, August (about 206 hours) has the most, while June during the rainy season (about 136 hours) has the least.
Power generation varies by season, so conducting an annual power generation simulation and selecting the capacity of storage batteries to match the times when electricity is used the most is key.
■ Areas with parks and green spaces require attention to fallen leaves and dirt
The Nishi Ward materials (2019) state that there are 50 parks and green spaces within the ward. On roofs close to parks and trees, fallen leaves and dirt can easily accumulate on panels, leading to shading, which may result in decreased power generation. Kakeru Koumuten Co., Ltd. can also handle solar panel cleaning with specialized brushes and rain gutter cleaning.
■ In a district with many small households, choose the capacity of storage batteries according to electricity usage
The Nishi Ward materials (2019) indicate that the average number of people per household is 1.87, the second lowest in Yokohama City. The amount and timing of electricity usage vary depending on the number of household members and their time spent at home, so it is important to select the capacity of storage batteries according to your household’s electricity usage. Kakeru Koumuten Co., Ltd. allows you to compare “solar power only” and “solar power + storage battery” through a financial simulation.
Our company is based in Yokohama City and handles many exterior construction and solar power projects in Nishi Ward, Yokohama.
We are happy to assist with partial roof repairs such as roof overlay work, roof replacement, and leak repairs, as well as other repairs! Please feel free to consult us for any sudden troubles!
Service Area in Nishi Ward, Yokohama City
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo.
List of Areas in Nishi Ward, Yokohama City
Nishi Ward Akamoncho / Nishi Ward Higashigaoka / Nishi Ward Isecho / Nishi Ward Oimatsucho / Nishi Ward Okano / Nishi Ward Kasumigaoka / Nishi Ward Kitakaruizawa / Nishi Ward Kitakou / Nishi Ward Kusunokicho / Nishi Ward Kubomachi / Nishi Ward Goshoyama / Nishi Ward Sakaienotani / Nishi Ward Sakuragicho / Nishi Ward Asamadadai / Nishi Ward Asamacho / Nishi Ward Takashima / Nishi Ward Chuo / Nishi Ward Tobecho / Nishi Ward Tobe Honmachi / Nishi Ward Nishitobecho / Nishi Ward Nishihiranuma / Nishi Ward Nishimae / Nishi Ward Hanasakicho / Nishi Ward Hamamatsucho / Nishi Ward Higashikubocho / Nishi Ward Hiranuma / Nishi Ward Fujidana / Nishi Ward Minatomirai / Nishi Ward Minami Karuizawa / Nishi Ward Minami Sachi / Nishi Ward Minami Asamacho / Nishi Ward Miyagatani / Nishi Ward Miyazakicho / Nishi Ward Motokubomachi / Nishi Ward Momijigaoka
・Leave your exterior wall painting in Nishi Ward, Yokohama to Kakeru Koumuten Co., Ltd.!
・Leave your roof renovation in Nishi Ward, Yokohama to Kakeru Koumuten Co., Ltd.!
・Leave your exterior renovation in Nishi Ward, Yokohama to Kakeru Koumuten Co., Ltd.!
・Kakeru Koumuten Co., Ltd.’s construction achievements
・Kakeru Koumuten Co., Ltd.’s after maintenance
・Kakeru Koumuten Co., Ltd.’s construction menu and price list
・Kakeru Koumuten Co., Ltd.’s staff blog and announcements
・We explain the importance of getting multiple estimates and points to compare!
・12 major manufacturers of solar power generation! We also introduce features and selection points!
・What are the installation costs for solar power generation? We thoroughly explain tips to reduce costs!
・What are the best places for installing solar power generation? We also introduce points for selecting installation locations!
・Check out our solar power generation estimates here!
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contact Kakeru Koumuten Co., Ltd.
Kakeru Koumuten is a young company whose team is, on average, in their late twenties, but our skills are second to none.
Our greatest strength is that we handle scaffolding, roofing and painting entirely in-house. In an industry where these tasks are usually divided among contractors, our complete service simplifies project management and helps keep costs down. Above all, if a problem arises, we respond promptly.
We proudly describe ourselves as the youngest and most helpful renovation company in Kanagawa!
