Energy
Power purchase agreement
A power purchase agreement, or PPA, is a long contract between a generator and a buyer setting the price, the volume and the term for electricity. It is what makes a project financeable, because it turns expected generation into contracted revenue.
Terms commonly run for many years, which is why a buyer looks closely at whether the generator can still be there at the end of it.
Steady output makes a better PPA than large peak output, which is most of the argument for combining sources and adding storage.