Sizing solar system
How did we know how many solar panels, batteries, and what size inverter and charge controller we needed?
We didn't know anything about solar power or RV solar systems and started researching different websites for solar calculators to use to help determine what we needed. We found a few on vendor sites like Renogy.com and some on blog sites like ParkedinParadise.com.
These calculators each had features we liked, but weren't something we could include in our blog. So I made my own with a few adjustments based on what we've seen over time in our van.
We knew we wanted 12 volt lithium batteries, flexible solar panels, mppt charge controller, and a pure sine wave inverter, so we factored these specific elements into our calculator.
We researched each electric appliance for our van to determine the number of amps or watts generated by each device. For instance, a 700 Watt microwave is AC powered and may have a peak wattage slightly higher than specified for the product. Or, should we or should we not get a water heater for our shower (and for the record, it was the big one at 1440 Watts and takes 30 minutes to heat 4 gallons of water). It might be something as simple as a 2 Amp DC charger to charge our mobile devices. If your devices are listed with Amps, then use the calculation Amps * Volts = Watts. A 2 Amp DC charger would then be 2*12=24 Watts.
We put each device in a small list.
| Device | Watts | Hours | AC/DC |
| Fridge | 25 | 24 | DC |
| Heater | 24 | 8 | DC |
| Water pump | 50 | .5 | DC |
| Fan | 13 | 8 | DC |
| LED Lights | 15 | 1 | DC |
| Phone Charger | 24 | 2 | DC |
| Microwave | 900 | .5 | AC |
| TV | 80 | 2 | AC |
| Induction Plate | 800 | .5 | AC |
| Water Heater | 1440 | .5 | AC |
If we only use the water heater on specific days, and don't use the microwave or induction plate at the same time, we can get away with 200Ah of battery power, a 40 Amp charge controller, 320 Watts of solar, and a 2000 Watt inverter.
However, if we want to use the water heater, microwave, induction plate and all the DC devices at the same time... We're going to need 300Ah of battery power, a 60 amp charge controller, 450 Watts of solar, and a 3000 Watt inverter.
Solar System Calculator
| Device | Watts | Hours | AC/DC | Result | |
|---|---|---|---|---|---|
| Daily Watt Hours | |||||
| Wh | |||||
| Ah 12V Battery Required |
W Minimum Solar Required |
W Charge Controller |
W Minimum Inverter |
