Using Solar Electricity

Continuing from the Off-grid Solar Electricity Overview this post describes the ways electricity collected from the sun is put to use in El Terreno.

Automotive (12 Volts DC)

Electricity is stored in the batteries at a nominal 12 volts DC. The most direct and efficient way to use the electricity is to use automotive devices that plug into a “cigarette lighter” plug. Running directly on 12 volts we have

USB (5 Volts DC)

For things that are USB powered we use a 4 port USB car charger

  • charging cell phones
  • charging the bluetooth speaker
  • humidifier

Standard House Outlet (120 Volts AC)

Lastly we have a 1000 watt pure sine wave inverter for powering 120 volt AC appliances

  • freezer
  • coffeemaker
  • coffee grinder
  • blender
  • immersion blender
  • various small battery chargers

Since the inverter has to change the current to AC and increase the voltage, it has the biggest conversion losses. It drains power (even when everything connected to it is off) so we shut it off at night.

By far our biggest electricity user is the freezer. We tried powering it with a cheap modified sine inverter, but we kept running out of power during the rainy season. Since we upgraded the inverter, the PV panels were able to supply all of our electricity, even on cloudy days. The freezer is well insulated enough that all the contents stay frozen overnight with the power off.

With 1000 watts inverter we have to check how many watts the appliances use before buying them. Things that heat or cool use the most power. All the coffee makers we found in the US, used more than 1000 watts, but we were able to find a single cup coffee maker in Mexico that only uses 650 watts. It’s still puts a strain on our little power plant, so we have to make sure the batteries have enough charge before making a cup. Off-grid solar coffee, what a luxury!


mom December 07, 2018

this is very cool! you’re brilliant, to work all this out.

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