Which direction should fixed panels face in the Northern Hemisphere for the most output?
AnswerSouth
South-facing panels catch the most sun over a day north of the equator.
Science · Facts & stats
Solar facts & stats
8 fact-checked facts about solar power, from the sky to your roof, each with the reason behind it. 4 more are in today's round and join this page after it closes.
The basics
Do solar panels work on cloudy days?
AnswerYes, at reduced output
Diffuse light still generates power, typically 10 to 25% of a clear-sky day.
Going deeper
What device converts panel DC power into AC for your home?
AnswerAn inverter
The inverter is the brains of a rooftop system and often the first component to need replacement.
Roughly how long do modern solar panels keep producing at least 80% of their rated output?
AnswerAbout 25 to 30 years
Most manufacturers warrant 80 to 87% output at 25 years; real degradation is around 0.5% a year.
What is net metering?
AnswerGetting credit for surplus power you send to the grid
Net metering lets customers offset consumption with exported solar, though rules vary widely by utility.
Which US federal incentive reduced the cost of home solar in the 2020s?
AnswerA 30% investment tax credit
The residential clean energy credit covered 30% of system cost under the Inflation Reduction Act of 2022.
Expert level
What is the theoretical efficiency limit of a single-junction silicon solar cell?
AnswerAbout 29 to 33% (Shockley–Queisser limit)
Single-junction cells are capped near 33%; commercial panels reach 20 to 23%, tandem cells can exceed the limit.
Why do grid operators care about the 'duck curve'?
AnswerSolar floods the midday grid and demand ramps steeply at sunset
The duck-shaped daily demand curve is why batteries and demand shifting matter as solar share grows.
Know these cold?Today's round is five questions like these, 20 seconds each. Your streak and level follow you to every arena.Play today's round