How to cool your home from the power of the sun
A rough sizing and cost tool for running air conditioning overnight on solar panels and a battery. Indicative only, on UK summer assumptions, and not a quote.
The answer
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Your home
How to measure this on Google Maps
- Open Google Maps and search your address.
- Switch to satellite view, then zoom in until the roof fills the screen.
- Find the scale bar in the corner (for example 2 m) and use it as a ruler.
- Estimate the flat section's length and width in metres, then multiply the two.
- Do the same for any pitched slope facing roughly south, and put that in the second box. Skip north-facing slopes, and skip the garage unless its roof is flat too.
We are measuring roof space suitable for solar panels in the UK. From this Google Maps satellite image (north is up on desktop; on mobile the orientation is shown) and its scale bar, give two areas in square metres: (1) the flat or low-slope roof usable for panels, and (2) the south-facing pitched roof suitable for panels. South-facing can be anything from south-south-west to south-east, it need not face due south. Ignore north-facing pitched roof. This is for a rough model, so estimates are fine.
Extras
Suggested setup & indicative cost
What's behind the numbers
Each bedroom is assumed to draw about 2.2 kWh of electricity over a 9-hour night (a ~2.5 kW cooling unit at a typical efficiency, cycling roughly a third of the time). "Whole house" scales with floor area instead.
The battery is sized to cover the night with ~30% headroom, then rounded to a real-world size. Solar is sized to replace the day's electricity (cooling + a typical household base load + any EV charging) on an average UK summer day, capped by the roof area you entered. A flat roof yields roughly 0.16 kWp per m² once you allow for tilt and spacing.
Costs use round UK figures: solar ~£1,400/kWp, battery ~£650/kWh, aircon ~£2,000 per room (more for whole-house), EV charger ~£1,000. The range is −15% to +20% around that.