Van & RV solar sizing chart
By Frank Zale · Last updated
A reference for planning and for citation. Every figure here is generated from the same formulas the calculator uses, documented on the methodology page, so the chart cannot drift away from the tool. Free to quote or reproduce with a link back.
By how you travel
At 4.5 peak sun hours (US annual average), LiFePO4, two days of autonomy, 12V.
| Profile | Daily use | Solar | Battery | MPPT | Inverter |
|---|---|---|---|---|---|
| Weekender Fridge, fan, lights, and phones for short trips off shore power. | 600 Wh | 178 W | 125 Ah | 20 A | 1,500 W |
| Part-timer Adds a laptop and Starlink for remote long weekends. | 1,000 Wh | 297 W | 209 Ah | 40 A | 1,500 W |
| Full-timer Everyday remote work, Starlink, and a bit of electric cooking. | 2,540 Wh | 753 W | 530 Ah | 80 A | 1,500 W |
By van type
Representative build for each vehicle, same conditions as above.
| Vehicle | Daily use | Solar | Battery | MPPT |
|---|---|---|---|---|
| Mercedes Sprinter 144 | 1,300 Wh | 386 W | 271 Ah | 50 A |
| Mercedes Sprinter 170 | 2,540 Wh | 753 W | 530 Ah | 80 A |
| Ford Transit | 1,365 Wh | 405 W | 285 Ah | 50 A |
| RAM ProMaster | 1,965 Wh | 583 W | 410 Ah | 80 A |
| Skoolie (bus conversion) | 3,510 Wh | 1,040 W | 732 Ah | 100 A |
| Truck camper | 840 Wh | 249 W | 175 Ah | 30 A |
Same build, different regions
A steady 1,500 Wh/day build. This is the table most sizing guides omit, and it is why builds that work in summer fail in December.
| Region | Peak sun (annual / winter) | Solar, annual | Solar, winter | Winter penalty |
|---|---|---|---|---|
| National average (US) | 4.5 / 2.5 h | 445 W | 800 W | ×1.8 |
| Arizona | 6.5 / 4.8 h | 308 W | 417 W | ×1.4 |
| California | 5.4 / 3.8 h | 371 W | 527 W | ×1.4 |
| Texas | 5.3 / 3.9 h | 378 W | 513 W | ×1.4 |
| Pacific Northwest | 3.8 / 1.5 h | 527 W | 1,334 W | ×2.5 |
| United Kingdom | 2.5 / 0.8 h | 800 W | 2,500 W | ×3.1 |
| Australia | 5.5 / 4 h | 364 W | 500 W | ×1.4 |
| Germany | 3 / 1 h | 667 W | 2,000 W | ×3.0 |
Appliance energy reference
Typical draw and realistic daily runtime for 19 common van and RV loads, sorted by daily consumption.
| Appliance | Watts | Typical hours/day | Wh/day |
|---|---|---|---|
| Induction cooktop | 1,500 W | 0.4 | 600 Wh |
| 12V compressor fridge | 45 W | 10 | 450 Wh |
| Instant Pot | 900 W | 0.5 | 450 Wh |
| Starlink (Standard) | 50 W | 8 | 400 Wh |
| CPAP (no humidifier) | 40 W | 8 | 320 Wh |
| Laptop | 65 W | 4 | 260 Wh |
| Roof vent fan | 25 W | 8 | 200 Wh |
| Electric kettle | 1,000 W | 0.2 | 200 Wh |
| 12V heated mattress pad | 45 W | 4 | 180 Wh |
| Microwave | 900 W | 0.2 | 180 Wh |
| Electric blanket | 55 W | 3 | 165 Wh |
| Coffee maker | 800 W | 0.2 | 160 Wh |
| WiFi router / cell booster | 10 W | 12 | 120 Wh |
| Diesel heater (running avg) | 30 W | 4 | 120 Wh |
| TV / monitor | 40 W | 2 | 80 Wh |
| LED lights | 15 W | 4 | 60 Wh |
| Phone charging | 10 W | 3 | 30 Wh |
| Camera / drone charging | 30 W | 1 | 30 Wh |
| Water pump | 50 W | 0.5 | 25 Wh |
How to read these numbers
Solar figures already include a 0.75 real-world derate, so they are what you should actually buy rather than a theoretical best case. Battery figures assume two days of autonomy at 80% depth of discharge on LiFePO4; on AGM, multiply by 1.6. Controller and inverter sizes include the standard 1.25 margin and are rounded to real product sizes.
The regional table is the one worth studying. The same build needs roughly three times the array in a UK December that it needs in an Arizona summer. Sizing on an annual average is the single most common reason a system that felt generous in July runs flat in November.
Citing this chart
Free to quote or reproduce, in whole or in part, with a link back to this page. No permission needed. If you would rather give readers the interactive version, the calculator embeds free on any site.
Method, constants and sources: methodology. To run your own numbers rather than reading a table, use the calculators.