Blog
Research, methodology notes, and the occasional look at how this calculator stacks up against others.
November 1, 2026Electric Cars, Solar Panels and Your Power BillAn electric car makes your power use jump. How many solar panels would offset it, does going electric actually save money, and is charging from the grid as bad as burning gas? A simple tool answers all three for your car and your area, with carbon counted in trees.
October 28, 2026Checking My Calculator Against NLR's System Advisor ModelI ran the same 50 homes through this calculator and through SAM, the free modeling tool from the National Laboratory of the Rockies. With a home's own meter data they agree within 0.74%. With typical homes alone, they agree on average but can miss one home by 10% or more.
October 25, 2026Building an Hour-by-Hour Solar CalculatorHow I rebuilt this calculator's engine with Claude, an AI model: testing it against 700 simulated homes, working out how much data it needed, and what that changed, from electric heat to car charging to rates that change by the hour.
October 3, 2026Thinking About Balcony SolarWhat it took to build a calculator for plug-in balcony kits: hundreds of new PVWatts runs at every angle, a tool for the angle your balcony actually allows, why a smaller kit often wins, where clipping bites, and why I left batteries out.
September 20, 2026When a Battery Actually PaysA home battery is sold as the thing that makes NEM 3 work. On a real PG&E quote it is often the thing that stops the investment working. Why batteries struggle on this calculator, the one case where the pack pays for itself, and an interactive model of the levers that decide it.
September 18, 2026Gas vs. Electric: The Energy and Carbon Math, Made VisibleHow much energy is actually in a gallon of gas? Why does an electric car's carbon footprint depend on where you live? Interactive tools for the energy and emissions math behind gas vs. electric — and the grid dynamics that drive it.
September 12, 2026I Fed the Same Solar Quote Into Six Calculators. Here's What Came Back.I ran the same $300/month bill and system through six free solar calculators and a sourced reference model. The verdicts ranged from a 264% "obvious yes" to cash investing winning outright — almost entirely because of one hidden assumption about exported power.