In solar power (PV) proposals, payback period, savings and return on investment all rest on one estimate: how much electricity the system will produce per year.

What is PVGIS? PVGIS is a free tool developed and maintained by the European Commission’s Joint Research Centre (JRC) that provides information on solar radiation and photovoltaic system performance. It covers any location in the world except the North and South Poles and requires no registration (JRC PVGIS).

How does it shape a proposal? Inputs such as location, panel tilt and orientation, installed capacity and system losses produce a monthly and annual production estimate. Compared with consumption, the estimate drives the self-consumption rate and, from there, the savings and payback calculation.

What a reliable proposal should make clear

• State the assumptions: Tilt, orientation, loss rate and the data source used should be stated in the proposal.
• An estimate is not a guarantee: Production varies year to year with weather, shading, soiling and equipment performance. The proposal should say it is an estimate.
• Check the site: Shading and roof conditions can change a desk-based estimate.
• Financial assumptions: Electricity price, exchange rate and maintenance cost assumptions should be stated separately.

The Solar Keywork proposal platform calculates production estimates with PVGIS data and shows the assumptions in the proposal report. Demo requests: support@keywork.ai