For homeowners and businesses (e.g., hotel, supermarket) looking to install rooftop PV and batteries to reduce electricity bills, and even sell surplus power back to the grid.
Breakdown of how much would it cost
How much would it save you
Solar PV and battery sizing
Tailored to households or businesses
Commercial
Ground-Mount/Floating PV & Battery
For project developers evaluating large-scale ground-mounted or floating solar PV systems with direct grid connection. Grid-scale battery storage can also be seamlessly integrated.
Ground-mount & floating PV systems
Grid-scale battery system
Large-scale capacity planning
NPV, IRR & full financial analysis
You can switch between modes at any time from within the tool.
In Development
Commercial Mode Coming Soon
The ground-mount and floating PV analysis module is currently in development.
It will include full grid-export modelling, large-scale capacity planning,
and detailed financial analysis for project developers.
In a nutshell, this tool help to estimate how much would it cost to install a solar PV and battery system for your house or businesses. It is free and open-source for everyone to use.
The tool requires minimum input to run, only the annual electricity consumption or bill, and estimation of roof area. Users are able to select built-in generic load profiles for domestic, commercial, industrial, EV stations and data centers.
It's built-in database for solar PV, inverter and battery means that users don't need to find these information themselves. This is currently being constantly improved by our team.
Users can select an approach to size their battery solution, either to maximise savings or increase self consumption for their house.
The tool can currently provide: (1) CAPEX breakdown and cost estimation, (2) Cash flow analysis with NPV & break-even year, (3) Interactive hourly power simulation, and (4) Environmental impact estimates.
New features are coming soon, including auto-routing to financing policies, options to reduce system costs, PDF export for analyses, and downloadable results.
Please help our team improve this tool by sending a feedback.
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Open-Meteo ERA5: 5-year hourly reanalysis (~25 km). Global coverage. Uses Hay-Davies transposition for tilt/azimuth.
MERRA-2 / CERES: 20+ year satellite + reanalysis climatology (~50 km). Global coverage. Powered by NASA POWER API.
System Specifications
Maximise Savings
NPV-optimal size: auto-scaled to your system
Self Sufficiency
Minimum system size to hit your % target
% of annual demand covered by solar + battery (not grid)
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Select your region to auto-populate typical installation cost figures. You can override either field manually by switching the region to Custom.
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Fixed one-time cost regardless of system size. Covers site survey, equipment delivery, scaffolding / access equipment hire, and project management.
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Labour and materials cost per kWp installed. Larger systems benefit from economies of scale where the fixed mobilisation cost is spread across more kWp, reducing the effective total cost per kWp.
Economic Data
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Default value of $0.50/kWh is based on the average UK electricity price of ~£0.30/kWh, converted to USD at approximately £1 = $1.65.
Adjust this value to match your local electricity tariff for accurate savings calculations.
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The rate your utility pays for excess solar electricity exported to the grid (feed-in tariff).
Set to $0.00 if no export tariff is available in your area. In this case, exported energy will earn no revenue and the system will be sized purely on self-consumption savings.
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The discount rate reflects the cost of capital (or opportunity cost) used to calculate NPV. For businesses, this is often the Weighted Average Cost of Capital (WACC).
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Default value of 0.2 kgCO₂/kWh is based on the UK grid 2025 data published by DESNZ.
This is a relatively low emission factor. If your grid is more carbon-intensive (e.g. coal-heavy regions), the environmental benefits of installing solar + battery will be significantly greater.
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No results yet
Enter your parameters and click "Calculate System Size" to see results.
Key Financial Metrics
Total CAPEX
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Upfront investment
Saving
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Average per month
Break-even
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Discounted NPV
Annual electricity cost / revenue
No solar + battery
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With solar
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Annual saving
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The annual saving combines: 1. Money saved by buying less electricity from the grid 2. Revenue earned from selling surplus electricity back to the grid (if any)
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How to finance this?
Coming soon.
CAPEX Breakdown
Hourly Power Profile
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Cumulative Cash Flow & Break-even Analysis
Positive NPV
Negative NPV
Environmental Impact
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tonnes CO₂/year saved
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tonnes CO₂ lifetime
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equivalent trees planted
Recommended System Configuration
Solar Array
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Battery Storage
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Annual Production
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Solar generation
Self-Sufficiency
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Output:
-kWp
Peak system capacity
Generation:
-kWh/yr
Annual production
Irradiance:
-kWh/m²/day
Average daily solar
Financing Your Solar System
Common schemes and options to reduce upfront cost
🏦 Green / Solar Loans
Specialist lenders offer 0%–5% APR loans for renewable energy systems. Repayments are often offset by your energy savings, making the net monthly cost close to zero.
Global
🏠 ECO4 & Government Grants (UK)
UK homeowners may qualify for grants covering part or all of the system cost, depending on income and property EPC rating. Check via Simple Energy Advice.
UK only
☀️ Solar PPA / Lease
A third party installs and owns the panels; you buy the electricity at a discounted rate. Zero upfront cost, but you don't own the system or claim the export tariff.
Global
⚡ Smart Export Guarantee (UK)
Not a loan, but UK grid export tariffs (SEG) can materially improve payback. Check Ofgem's list of licensed SEG generators to find the best rate.
UK only
This is informational only — consult a qualified financial adviser before committing to any scheme.