I have read a lot about off grid solar systems. Most of the reasons I have seen to not directly attach PV panels to an inverter without a battery are:

  1. Under voltage when not enough sunlight.
  2. Pulling to much current due to the power curve from pv panels (Ohm's law) resulting in under voltage.
  3. Over voltage from PV panels exceeding the maximum voltage for an inverter.
  4. Under voltage from burst when starting an appliance

My use case: I want a long shelf life solar generator to use for camping or in case of a grid failure. Where I live, the majority of the time it is sunny. So if there were a storm that knocked out the grid, its more likely to be sunny faster than the grid to be repaired. I want to use it to run charge power tool batteries, run laptops, etc.

So here is what I have done enter image description here

This takes 2 12V 100W PV panels. They go through a voltage regulator which regulates the voltage to 12V or less. A 1000V 10A diode on the positive output to prevent current from heading back into the regulator if one of the panels were blocked.

enter image description here

The outputs are wired together in parallel. It goes through a 2 farad capacitor.

and into an inverter.

The inverter has low voltage protection built in.


  1. Anything wrong with this setup?
  2. Anything I am not protecting against?

1 Answer 1


Looking through the comments regarding that capacitor it doesn't seem to be a 2 F capacitor.

If it were a 2 F capacitor the amount of energy stored would be something like 144 Joule. This would mean it could (theoretically) supply 144 Watt for 1 second. Good enough for you?

The information about the buck regulators says a lot of things, no telling of which is true.

  • 200 max output, but only 8 A current. Which at 12 V would be 12 x 8 = 96 W
  • 4 A current output without heat sink (48 W @12 V).

Possible faults that may occur:

  • Overheated components
  • Lower power output than expected
  • Unpredictable behaviour by power limited by cells, contact resistance, capacitor discharge
  • Soldered joints will break, you mentioned using this for camping. Unfastened wires connected to soldered joints will break...

I think you would be better off with placing a lead acid battery in this circuit instead of a capacitor.


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