Renewable power, benefits and challenges

Adding solar and wind capacity does not displace conventional capacity one for one, because their output is variable: solar generation peaks around midday while system demand peaks after sunset, so the evening ramp must be met from dispatchable sources. That temporal mismatch is the defining challenge, and the responses to it — storage, round-the-clock tenders, firm-and-dispatchable tenders that bundle variable generation with firm backing, and time-of-day tariffs that shift demand toward the generation window — are the corresponding instruments. Renewable shares of installed capacity and of generated energy diverge for this same reason, since capacity credit depends on when output arrives relative to when it is needed.