Nuclear fusion is the dream machine of energy: no smokestack, no coal train, no ordinary reactor fuel rods, just light atoms squeezed so hard they snap together and spill out astonishing energy. The twist is that fusion is both real and not ready. Scientists have crossed major milestones, but a lab triumph is not the same thing as cheap electricity on your wall socket. Here’s the simple version, without the fog.

Do you want to know how much electricity you will need tomorrow, next week, or next year? Do you wonder how the weather, the economy, and the technology will affect the energy supply and demand? If yes, then you are interested in energy forecasting.

A power purchase agreement, or PPA, is one of the most important contracts in modern energy — and one of the least understood. It is how solar farms get financed, how companies lock in electricity prices, and how power gets sold before it is even generated. Here is what a PPA is, how it works, and why it matters more than most people realize.