HomeSolarDex

Methodology

Where each number comes from and which numbers are our own arithmetic.

Data as of 8 Nov 2026, source: see Sources for every document and its read date

Numbers copied from documents

Battery capacity, continuous and peak power, warranty years, warrantied capacity and throughput limits are copied from manufacturer datasheets and warranty PDFs, shown in the battery table. Power station figures are copied from the maker's product page and shown on the power stations page. Each product has its source link in the notes section of its page. Where a document does not print a value, the table shows n/s (not stated) and we do not fill it from another site. How the warranty numbers compare is written up in warranties compared.

Numbers we derive

  • Left at end (kWh): usable kWh multiplied by the warrantied percentage, for example 13.5 x 70% = 9.45 kWh. Marked with an asterisk.
  • Throughput in MWh: where a datasheet gives cycles instead of MWh, cycles multiplied by kWh per cycle, for example 6,000 x 5.0 kWh = 30 MWh. Marked with an asterisk and explained in the product notes.
  • Typical market $ per kWh: a third party total price divided by its kWh, shown in the price section of the battery page and never attached to a model.

Runtime calculator

How the runtime estimate is builtCapacity per unit times units, times charge at start minus reserve, times one minus conversion loss, divided by the average load in watts, gives hours of backup.Capacity per unit x unitsdatasheet kWhxCharge at start minus reserveour assumption, editablex1 minus conversion lossour assumption, editable/Average load in wattssum of watts x share of time=Hours of backupestimate, not a guarantee
How the runtime estimate is built. Capacity per unit times units, times charge at start minus reserve, times one minus conversion loss, divided by the average load in watts, gives hours of backup.

The battery runtime calculator follows the formula above: hours = capacity per unit x units x (charge at start minus reserve) x (1 minus conversion loss) divided by average load. Average load is the sum of each device's running watts times its share of time running. The method of multiplying watts by hours and dividing by 1,000 is the one on the U.S. Department of Energy Energy Saver page; the refrigerator share of one third is also from that page.

Device watts are samples that we chose, because the DOE page states its own wattages are samples and prints no table. Charge at start 100%, reserve 0% and conversion loss 5% are assumptions of ours, not datasheet values. Capacity and power add up linearly across units, which is an assumption; check each maker's limits.

The calculator does not simulate solar recharging, temperature, state of health, inverter surge duration or per-circuit limits in a critical loads panel. A real installation can differ, and a licensed electrician working to NEC and local rules, or the maker, decides what is safe.

Dates

Every figure carries the day it was read, 8 Nov 2026 for all documents so far. Prices change faster than specifications; the price shown for a power station is only what the page displayed that day. Documents and read dates are listed on sources. Affiliate policy and the limits of the calculators are on about.

Not covered

Installed prices per model and electricity prices by state are not part of this site. The price section of the battery page explains which price sources were tried; the home battery cost guide shows the third party figures we do use. Programs that pay toward a battery are in battery incentives, and the federal credit has its own status page.