A couple bombs can take out a gigawatt+ generation plant. A couple dozen acres of solar panels will need much, much more, with each individual strike having far less impact and being far easier to repair after. On top of that, solar can be widely distributed and embedded in much smaller footprints, into civilian areas, and so on. Solar also has less infrastructure requirements such as access to water where destroying a dam for example can render one or more power plats inoperable.