Size the inverter on load and the battery on outage length. Inverter VA = (average watts / 0.8) x 1.25; battery Ah = (watts x hours) / (system voltage x efficiency x 0.5). A 2BHK flat at 434W needs about a 800VA inverter and a 220Ah bank for 4 hours.
Each page below builds a realistic appliance list for that premises type, runs the same sizing engine the live advisor runs, and shows the arithmetic behind every recommendation — plus the overload check most sizing tools skip.
On the load modelled here — three fans, six lights, a TV, a fridge and a router — a 2BHK flat averages 434W and sizes to a 800VA inverter with a 220Ah battery bank for 4 hours of backup.
Required VA = (average load in watts / power factor 0.8) x 1.25 safety margin, then rounded up to the nearest standard retail tier such as 800VA, 1100VA or 1500VA.
Battery Buddy escalates at 400W average load (to 24V), 800W (to 48V) and 2000W (to 96V). Higher voltage carries the same power at lower current, which reduces cable losses and heat.
No. Every page returns a VA rating, an Ah figure, a system voltage and a charger current with the formula shown, so you can compare dealer quotes on equal terms.
Battery Buddy is free, needs no sign-up, sells no batteries and shows every formula it uses. It is built by Flocci Technologies, an India-first AI-native software studio behind 30+ apps that share one Flocci identity.