Fact brief - Do solar plants require backup from fossil fuels? Do solar plants require backup from fossil fuels? Solar plants require backup, but it doesn’t have to be from fossil fuels. Go to full rebuttal on Skeptical Science or to the fact brief on GigafactThis fact brief is responsive to quotes such as this one. Fact briefs are created by contributors to Gigafact — a nonprofit project looking to expand participation in fact-checking and protect the democratic process.