15 engines

Solar

Payback by system-cost class, cash versus loan versus lease versus PPA, and what your actual incentive stack does to the number.

Every solar shopping conversation eventually reduces to the same handful of numbers: system cost, your electricity rate, your incentive stack, and how you are paying for it, cash, loan, lease, or PPA. These engines isolate each of those levers on its own, plus panel degradation and export-credit value, so a sales quote's headline payback claim can be checked against your own assumptions instead of taken on faith.

For the ideas shared across every Solar engine, see What Actually Moves Solar Payback.