Build one energy budget, then use it to plan storage, generation, and power delivery. These ten tools work for RV weekends, off-grid cabins, and boat energy planning. Each runs without JavaScript, and result links carry compatible inputs to the next step.
Working through more than one setup? Save calculated results to My plans to reopen, duplicate, and compare named plans. Device saving needs no account.
Start with what you need to run
Estimate daily appliance loads. Record watts, quantities, hours, and duty cycle; add named appliances and print a trip summary. Your Wh/day budget determines energy needs; it does not determine motor starting power.
Size the RV solar array and count panels. Use seasonal peak sun hours, then check panel fit on the roof using actual frame dimensions and clearances. Use the optional stored-energy deficit to budget extra solar for battery recovery over a chosen number of productive days.
Check DC cable voltage drop. Then have conductor ampacity, fuses, disconnects, grounding, and installation reviewed. For vessel-specific planning, the marine wire tool has separate marine assumptions.
A 100 W appliance running for 3 hours uses 300 Wh, or 0.3 kWh. At nominal 12 V, that equals 25 Ah before losses. Amps describe current right now; amp-hours describe charge accumulated over time. Compare batteries in Wh when their voltages differ.
Appliance watts are the starting point here. Battery sizing applies discharge conversion losses; solar sizing applies its own overall panel-to-load efficiency. Do not apply either loss twice to the same energy budget.
A worked RV weekend plan
At 1,200 Wh/day, two days of autonomy, 80% usable depth, 20% reserve of usable energy, and 90% delivery efficiency, nominal storage is 4,166.7 Wh: about 347.2 Ah at 12 V. Four peak sun hours and 70% overall solar efficiency require 428.6 W, or three 200 W panels.
A 1,000 W simultaneous AC load with 25% headroom suggests at least 1,250 W continuous inverter output. A measured 2,000 W total start event still needs a compatible surge rating and duration. Energy capacity alone does not establish battery/BMS current capability.
Planning assumptions to replace with real measurements
Our example defaults are starting points, not recommended equipment specifications. Winter sun, shading, temperature, battery age, and inverter idle draw can change the result substantially. Measure a full day, consult the actual battery and charger manuals, and compare a low-sun scenario before buying components.
For background, consult Victron’s Wiring Unlimited for battery and DC wiring principles and the Department of Energy solar guide for site-dependent solar considerations. These references do not replace applicable installation requirements.
Solar and RV planning FAQ
Can solar run my air conditioner?
First enter its measured daily energy and starting load. Check array space, seasonal generation, inverter surge duration, and battery current limits separately. A large enough panel nameplate rating does not guarantee continuous operation.
Should I choose 12 V, 24 V, or 48 V?
Higher voltage reduces current for the same power, but every charger, inverter, battery configuration, and DC appliance must be compatible. Compare scenarios with your equipment requirements before choosing.
Where is the RV fuse-size recommendation?
Voltage drop alone cannot select a fuse. Protection needs verified cable ampacity, terminal ratings, installation conditions, fault-current interrupt capacity, and equipment limits. This release leaves that decision to manufacturer instructions and qualified review.