Lesson learned: solar power and loads

For both personal and practical reasons my solar config was the most researched and planned part of my build.  It was time to see what she could do on a boondocking run.

Lesson:  the build has abundant power

I built the solar and house power system on the cheap.

  •  3x 190W mono panels were bought off a pallet from a local seller for something like 65c/watt.

  • wiring was landscaping zip cable

  • batteries were used golf carts, $120 for the pair.

  • Chinese 40A MPPT charge controller for $200

  • opportunity circuit for running non-essential loads cost about $20 in materials to implement

I don’t squander power (leaving lights on or whatever) but I had way more than I needed all the time.   Even on the stormy and completely overcast morning we had  the system Bulked 100w into the battery bank and had finished Absorption by noon.

On normal days I had hundreds of watts of untapped power on hand – that’s when I charged devices and ran heavier loads.  This process was automated with the opportunity circuit.  For example, I could leave the laptop and wifi hotspot plugged in but they would only charge when the house batteries were full.  I think this idea can really help ‘dwellers of limited means get by with less expensive solar installs.

I do plan on visiting Portland and other areas in the pacific northwest so we’ll how well she does there.

Lesson:  I don’t use much power at night

The opportunity circuit clicked off whenever battery voltage dropped below 100 state of charge (12.7v).  The phone and everything else kept working but on their own internal batteries.

In general I went to bed with the sun and woke with the sun.  Before I fell asleep I read the kindle which runs about a month on one charge.  :-) I don’t run a DVD player, xbox,  or flat-screen TV at night.  Or ever.  :-P

Some house power was used at night:

  • The maxxfan ran all night on the lowest setting for ventilation (pulling air in)

  • LED strip light was used for general illumination

  • parasitic loads from charge controllers, LVDs, etc.

Most mornings the bank was still at 12.7v where it had been the night before.  This suggests to me that I could probably get away with a small 40-50Ah LiFePO4 bank when my 6v batteries die.