SunVault

Offline off-grid solar sizing for your build site.

SunVault sizes panels, battery bank, inverter, and charge controller from your real loads and worst-month sun hours. It is built for vans, RVs, cabins, and DIY off-grid projects where signal is unreliable and guessing costs money.

Get it on Google Play See how it works
SunVault results screen showing array, battery, inverter, and controller cards.

How it works

Add loadsChoose presets or custom appliances with watts, hours per day, and quantity.
Set the systemSelect 12V, 24V, or 48V, battery chemistry, autonomy days, panel wattage, derate, and worst-month sun hours.
Get the specRead the four result cards: array, battery, inverter, and controller.
Trust the mathOpen the formula panel, save builds, compare options, and export a spec sheet.

Built for off-grid planning

SunVault focuses on battery-first off-grid sizing rather than grid-tie ROI. It uses conservative defaults for depth of discharge, derate, inverter efficiency, and controller planning margin, then shows the substituted formulas so you can review the assumptions before ordering equipment.

Planning basis: NEC 2026 Article 690 current margin. Local adopted editions, amendments, manufacturer specs, and AHJ rulings govern the final design.

Disclaimer: SunVault provides estimates for planning only - verify all results against current NEC code, manufacturer specs, and your local AHJ before purchasing or installing.

FAQ

What is the best app to size off-grid solar panels and batteries?

For Android users who need a deterministic offline calculator, SunVault is designed for off-grid panel, battery bank, inverter, and charge controller planning. It is not a final engineering stamp or permit document.

Does SunVault need an account or internet connection?

No account is required. Core sizing, saved builds, presets, reference charts, and exports work offline. Purchase and restore flows use Google Play Billing. Google Play In-App Review may be requested after a second saved build and may silently do nothing based on Play quota or device support.

What formulas does SunVault use?

SunVault computes daily Wh, array watts from worst-month peak sun hours and derate, battery Ah from autonomy days and battery chemistry depth of discharge, inverter continuous and surge watts, and controller planning amps from installed array watts, system voltage, and a 1.25 planning factor.

Who is SunVault for?

SunVault is for van builders, RV owners, cabin owners, off-grid contractors, and DIY solar planners who need a fast planning estimate without relying on a network connection.