Adding more solar power

Adding more solar power

The previous example is very nice to try-and-error a bit during you DIY. But what if we need more power for example. Maybe some powertools on regular AC or the rest of the (tiny) house. The basics stay the same, but we add a little something.


Adding more solar power

To be able to power AC devices we need an inverter that will transfer the DC 12 Volts into regular grid-like 110V AC. Download the complete schematics as PDF

We didn’t really add more power yet, our previous setup was designed for 200 Watt daily. That is still accurate. We just added the possibility to connect regular AC appliances. This brings some extra considerations.

Just considering the Watts, we could easily run an AC drill or jigsaw for 20 minuts, since 600 Watts x 20 minuts (1/3 of an hour) also equals 200Watts. 

However Ohms law states the following: Watts = Voltage x Amperage

So 600Watt = 110Volt AC x 5.5Amps
But before the inverter this would mean: 600Watts = 12Vdc x 50Amps. Excuse me, yes 50 Amps, so bye-bye small 10Amp fuse. Two possiblities can manage this problem.

  • A heavier 50A charge controller with updated fuses
  • Connecting the inverter directly on the battery with a seperate 50A fuse (unless it’s already build in the inverter) Don’t ignore the required AWG size

Another thing to keep in mind is the fact that a peak current will occur if an electric motor is switched on. To be save, buy a larger inverter for example 1000 or 1500 Watts. This would result in an even bigger fuse than 50 Amps in the 12Volt circuit. Regular motors like a drill or jigsaw require upto 3 or 4x continuous current, pumps like in a refrigerator upto 6 or 7x more.


How about some actual extra power ?

To upgrade the following parts have been added or changed:

  • Added another “12Volt” solar panel
  • Use a bigger battery or two 12Volt batteries in parallel
  • Use a big charge controller (12Volts / 20Amps) BSV20A for example.
  • Connected the inverter directly on the battery (Please keep in mind this requires thick wiring: AWG 6 or bigger and keep these wires as short as possible)
  • Remember to ground the required parts

A schematic can be downloaded as PDF

Quick math:

Battery of 200Ah needs a charge current between 16.7 – 25Amps, so two 130Wp panels or better yet 150Wp will do that. The battery can hold 12V x 200A = 2400W. The 20% (Our reason) maximum discharge would still provide 480 Watts to be used daily.


Even more power »