What would your solar assumptions mean?
Use a quote and the installer’s generation estimate. Change the assumptions and see the simple annual benefit and payback.
This calculator uses figures you supply, not a roof survey or a guaranteed Irish average. If you need a generation estimate first, try SEAI’s solar calculator ↗ and ask an installer to assess shading, roof direction and system design.
The calculation, plainly.
Annual benefit = generation used at home × avoided import price + exported generation × export price − annual reserve. Simple payback = net installation cost ÷ positive annual benefit.
Simple payback ignores financing, inflation, equipment degradation, tariff changes, downtime and the timing of replacement costs. It does not model a battery half-hour by half-hour. Treat the result as a way to challenge assumptions, not a promise or investment recommendation.
Ask for generation, self-consumption, battery and export assumptions in the written proposal. A high self-use figure needs a credible daytime-use or storage plan. Check your electricity tariff, export terms and whether price units are euro or cents.
Get the design behind the numbers
Read our solar costs and grant guide, compare written quotes or send your solar project. An enquiry is not an installer booking and is not forwarded automatically.