Energy & Sustainability
Solar Energy Calculators & Guides
System size → output → money saved → payback. Keep power ratings, generated energy and financial return separate.
Start with the panel ratings and a site-specific generation estimate. Once annual output is clear, use your installation quote, self-consumption and import/export tariffs to compare savings and payback. This hub does not provide a roof-design or battery-sizing calculator.
What do you want to work out?
How much electricity could my proposed system produce?
Inputs to gather
Panel count and rated power, location, orientation, tilt, shading and system-loss assumptions.
A power rating is not an annual energy forecast. Use a site-specific estimate from PVGIS or PVWatts, and check whether losses are already included.
What could that output save, and when could the system pay back?
Inputs to gather
Quoted system cost, expected annual generation, self-consumed share, retail electricity price, export tariff and ongoing costs.
Self-used and exported energy have different financial values. Simple payback and longer-term projections depend on the assumptions; neither guarantees a return.
Understand solar savings and paybackGuides behind the calculations
Convert inputs when needed
- ft² → m²
Compare roof areas and drawings stated in different units; area alone does not establish installable capacity.
Before choosing a calculation
Can I use one country-wide yield for my roof?
Use a location- and roof-specific estimate instead. PVGIS and PVWatts accept site and system inputs; check orientation, losses and shading assumptions before transferring the estimate to the payback calculator.
Does the payback calculator size a battery?
No. Storage is a separate decision involving usable capacity, charging patterns, losses, export income forgone and purchase cost. Do not treat improved self-consumption as free.
Should I add system losses again after using a yield estimate?
Check the estimate’s boundary. If the predicted output already includes the relevant losses, applying them again understates generation. The output guide explains the distinction.
Your next decision
Use consumption records to judge how much generation you could use rather than export.
Compare your charging schedule with predicted generation before assuming the car will absorb solar surplus.