Can residential solar cover residential AC demand? To answer this question, we have downloaded hourly data across 2025, from NASA Earth Observatory, across 25 major cities. We estimate that the average home, with 20m2 of solar modules (a 5kW array) can cover 80% of the energy costs of keeping indoor temperatures below 20C. The bigger challenge is that the array throws off 5-10x more energy than needed just for AC, which requires other forms of flexible demand. Numbers are shown in the index tab. And underlying calculations follow for each major city, in the backup tabs.
Air conditioning is 12% of US electricity demand. But only c20% of European households have air conditioning (AC). Summer heatwaves are an annual reminder.
But interestingly, in cities like London, temperatures are 60% correlated with solar insolation, per the chart below from NASA Earth Observations.
Hence to what extent could a home with 20m2 of residential solar (5kW) self-generate the AC energy to keep indoor temperatures below 20ºC ?
To answer this question, we downloaded hourly temperature data and insolation data for 24 cities. Our findings are shown by city, in the title chart for this webapge.
The average global home with 20m2 of solar modules could self-produce 80% the AC power needed to keep indoor temperatures sub-20ºC, at 2.75 kWh per cooling degree day. The other 20% mainly reflects times when the sun has already set, but indoors remains hot, especially 6-8pm, or later at night.
Many European countries could achieve 90% coverage of their AC needs with resi solar, especially in cooler-climate regions such as Stockholm (99% cover), London (98%), Warsaw (93%), Berlin (92%), Vienna (91%). This supports our forecasts for future load growth in Europe and solar growth in Europe.
5-10x more solar energy is generated, however, than is needed just for AC. The best use for this excess solar is to absorb it smartly, e.g., in the batteries of electric vehicles, heat pump hot water tanks, or to pre-cool space before the sun sets. It is not a shortage of energy that precludes AC in Europe, only of action/initiative.
Can residential solar cover residential AC demand? Solar generation, by hour, as correlated with temperature, for coverage of potential AC demand can be stress-tested by city in the full data-file.