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RV Power System Checker

Compare your daily battery-powered energy use with an estimate from your solar array. See how much energy could be left over or missing each day, and how a daily deficit relates to the battery energy above your chosen minimum level.

Enter your numbers below or use My Setup to replace compatible inputs. Review the values and complete any missing assumptions. Solar is optional. The Daily Power Consumption Calculator can provide your DC and inverter AC totals.

Not sure what to enter? Read the step-by-step guide.

Your inputs

What gets replaced?

Compatible fields are replaced with values from your saved setup, including blanks. Capacity values and units are replaced together where supported. Other fields stay unchanged. You can undo the replacement until you manually change one of the replaced fields. Edit My Setup

Your daily energy use
What does DC daily energy mean?
Energy used by devices powered directly from the battery system, in watt-hours each day. Use Daily Power Consumption to build this total. Do not include shore or generator-only loads.

Battery-powered DC devices. Leave blank if none.

What does AC daily energy mean?
Energy used by AC devices powered by the battery through an inverter, before inverter losses. Use Daily Power Consumption for this total; do not enter the whole RV total into both DC and AC.

Only AC devices powered by this battery through an inverter. Leave blank if none.

Your solar estimate
What does rated panel power mean?
Add the rated watts on the labels of the panels in this array. This is nameplate power, not a promise of continuous output.

Enter 0 or leave blank if no solar is available during this scenario.

Your battery
What does battery capacity mean?
Read the total battery bank rating in Ah or Wh from its label or documentation. Use the unit selected above; Ah also needs the bank’s nominal voltage.
What does battery level mean?
State of charge (SoC) is how full the battery is, expressed as a percentage. Use your battery monitor’s current reading.
What does minimum battery level mean?
This is the percentage of charge where you choose to stop using the battery. Check your battery or system guidance; the calculator does not choose a limit from chemistry.

Choose a level appropriate for your battery and system; the calculator does not choose a default based on battery chemistry.

This scenario assumes the listed energy use and sun conditions repeat each day with no shore, generator or alternator charging. Calculations stay in this browser.

System energy estimate

Your daily energy balance

Daily energy balance

Estimated daily difference

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Daily energy drawn from the battery—

Estimated usable solar energy—

Battery energy available above your minimum level—

What this means for your battery

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Enter daily energy, solar conditions if used, and your battery details.

This is an average-day energy comparison, not a time-of-day battery simulation or a check that an inverter, charger, battery, controller or wiring can handle instantaneous loads. Solar timing, weather and battery behavior may change the real outcome. A surplus does not guarantee that the battery stays charged throughout the day.

Edit your inputs
See calculation details, assumptions and sources

Battery-side load Wh/day = direct DC Wh/day + AC device Wh/day ÷ inverter efficiency (as a fraction). Usable solar Wh/day = panel nameplate W × peak sun hours × solar delivery efficiency. Daily balance = usable solar Wh/day − battery-side load Wh/day. A negative balance is a daily deficit; a positive balance is a surplus under these chosen average conditions.

Nominal battery Wh = entered Wh or Ah × nominal V. Battery Wh available now = nominal Wh × (current SoC − stop SoC) ÷ 100. Only with a daily deficit, days to stop = available battery Wh ÷ daily deficit Wh. This is a repeated-day energy quotient, not continuous runtime or a forecast of a particular clock time. The calculation does not add charge above 100% or model where surplus goes.

Example: 600 Wh/day direct DC and 400 Wh/day AC at 80% inverter efficiency draw 1,100 Wh/day from the battery side. A 400 W array at four peak sun hours and 75% overall solar delivery supplies an estimated 1,200 Wh/day, giving a 100 Wh/day surplus. With only two peak sun hours, solar supplies 600 Wh/day and the deficit is 500 Wh/day. A nominal 2,000 Wh battery from 80% to a 20% minimum battery level has 1,200 Wh available, or 2.4 repeated days at that deficit. These percentages are example inputs, not recommended defaults.

Use measured or documented energy use where possible. Classify battery-powered DC and inverter AC devices separately in Daily Power Consumption; shore or generator loads do not enter this battery balance. Choose PSH for the location and season and an overall delivery efficiency that includes relevant solar and storage losses without counting inverter losses twice. See Solar Size and Battery Runtime for the individual assumptions.

References: NREL PVWatts documents solar resource and system losses; US DOE describes real-world solar variation; Victron ESS describes a configurable minimum battery SoC. This checker is a simplified RV energy model, not a PVWatts simulation. See the site methodology.