How HeliosROI calculates your results
Guide text reviewed: . This date does not certify current tariffs or validated PVGIS results.
HeliosROI provides an initial estimate to help you compare options. It does not replace a technical survey, a professional quote or an analysis of your actual bills.
1. Estimating consumption and generation
Your annual electricity use is spread across the year using a typical hourly profile for your country. Solar generation is estimated from the location, system size and general system losses.
The calculation compares your electricity use with potential solar generation hour by hour. Solar energy used at the same time is counted as direct self-consumption.
2. Battery
When solar generation exceeds demand, a battery can store the surplus for later. If cheap grid charging is enabled, the cost of that electricity is deducted from the savings.
The battery is represented by a simple model. The results do not include battery losses, degradation or detailed inverter limits.
3. Savings, payback and ROI
Estimated annual savings are the value of the electricity you no longer need to buy, minus the cost of charging the battery from the grid.
Payback shows how many years of savings would be needed to recover the initial cost. ROI shows the accumulated result over twenty years, assuming annual savings stay the same.
4. What the estimate does not include
- Income or credit for exporting surplus electricity.
- Maintenance, finance, grants or equipment replacement.
- Panel and battery degradation.
- Future changes in electricity prices or consumption habits.
- Shading and the detailed characteristics of each roof.
How to use the results
Treat the results as a guide for comparing scenarios. For a more realistic estimate, enter your current electricity prices, consider your consumption habits and check the result with a qualified installer.