OffGridCalcs exists because sizing an independent power system is mostly arithmetic, and most of the arithmetic online is either hidden inside a black box or attached to someone trying to sell you panels. These tools do neither. Every calculation is written out, every assumption is stated, and the numbers lean conservative: losses counted, worst month rather than annual average, headroom left where equipment needs it.
Every calculator on this site shows its formula and states its assumptions, because a number you can't check is a number you can't trust. The tools are free, run entirely in your browser, and collect nothing.
These calculators are planning estimates. Final designs should be confirmed against component datasheets, manufacturer guidance and the electrical code that applies where you build.
How these calculators are built
Each tool starts from a question someone actually asks while planning a system, not from a formula looking for a use. The calculation is written out in the open so you can check it, the assumptions behind every default are stated, and the mistakes that quietly undersize real installations are listed rather than glossed over.
Nothing here is generated and published unread. Figures are cross-checked against the worked examples on each page, and where a rule of thumb is contested in practice, the page says so instead of pretending the matter is settled.
Contact
Corrections and suggestions are welcome: info@offgridcalcs.com