Adjust for panel temperature

Solar panels don’t actually deliver their nameplate rating in the real world. When they get hot they produce noticeably less power; when they get cold they produce a little more. This toggle tells the calculator to model that effect using the real ambient temperature from the weather feed.

Why it matters

A typical silicon panel is rated at 25 °C cell temperature. Real-world cell temperatures sit well above that on sunny days — a panel sitting on an Australian roof at noon can easily reach 60–70 °C internally, even when the air around it is only 30 °C. At those temperatures a panel delivers about 10–15 % less power than its rating would suggest.

The opposite happens in the cold. A clear, frosty morning in Calgary or the Scottish highlands gives a small bonus — a 0 °C panel under bright sun produces around 5 % more than its 25 °C rating. Most calculators leave this out, which understates winter output and overstates summer output.

What the toggle does

On (default): predicted production includes the temperature effect. Hot summer afternoons show realistically lower output; cold clear mornings show the small bonus.
Off: predicted production assumes the panels are at their rated 25 °C cell temperature. This is the legacy answer most other calculators give — useful if you want to compare like-for-like with another tool.

How big is the effect?

Concrete examples from the simulator:

Cool, clear March day in Melbourne: ~14 % less than nameplate at solar noon.
Mild April day in Melbourne: ~7 % less.
Cold (0 °C), bright winter morning: ~5 % more than nameplate.
Frosty (-10 °C), partly sunny morning: ~12 % more.

Over a whole year the temperature effect is usually a modest net loss in temperate climates (4–8 %), a larger loss in hot climates (8–12 %), and roughly neutral or slightly positive in cool sunny climates. Big enough to matter when you’re sizing a system or deciding whether you have enough headroom for an EV charge tomorrow.

Notes

The toggle only does anything when Use real weather is also on — without real ambient temperature there’s nothing to adjust against. When both are off the calculator returns the clear-sky theoretical maximum.
The model uses the standard silicon temperature coefficient of −0.4 % per °C off the 25 °C reference, with a 45 °C Nominal Operating Cell Temperature (NOCT). Premium panels with better coefficients will outperform the default; older panels may underperform. A future Expert-tier release will let you enter your panel’s exact spec.

Closes this tab and returns to the calculator.