About this calculator
A neutral, no-signup tool for sizing off-grid and backup solar systems — built because most online sizing calculators exist to route you toward a particular retailer's products.
Retailer calculators are useful, but they are sales funnels: they nudge you toward their own batteries and panels, often require an email, and rarely size the whole system end to end. This tool does the opposite. It is brand-agnostic, stores nothing, asks for nothing, and walks the full chain — load, battery bank, solar array, charge controller and inverter — so you leave with a complete picture you can price out anywhere.
The chemistry constants and formulas are documented on the methodology page. If you find an error, the contact link is below — corrections are welcome.
Built and maintained by Sri Murugan Systems, a software development company that builds independent, single-purpose web tools.
What "brand-agnostic" and "no signup" actually mean
The calculator runs entirely in your browser — there is no server-side account, no email capture, and nothing you enter is transmitted or stored anywhere. It doesn't sell or recommend specific battery, panel or inverter brands, and it isn't paid to favor any of them; the output is Ah, W and kWh figures you can price out with any manufacturer or retailer.
What this tool doesn't do
It is a sizing calculator, not an electrical design tool or a substitute for a licensed installer — it doesn't check your specific wiring, breaker sizing, code compliance or permit requirements, all of which vary by jurisdiction and installation. Treat its output as a starting bill of materials to plan and price a system, then verify the details with a meter, a datasheet and, for anything permanently wired, a qualified installer.