Off Grid Solar Power

   This is a off grid system not a grid tie, it will not feed back to the grid and stick it to the electric company. Well, it does stick it to them as I haven't had an electric bill since installing it in August of 2012. If you are trying to feed back to the grid or you are just trying to reduce your electric bill, look into a grid tie system using Solar AC Modules. These are easy DIY installs but they may not work as an emergency backup and you may have to jump thru some hoops with your electric company to get it connected to the grid. My intent is to build a practical self contained electrical system or as some folks would refer to as a doomsday system.


   The photo at the left is the mechanical room which contains the equipment that supplies all electric power to the house and the well. The solar electric power is being supplied by a single 135 watt solar panel mounted on the roof. The new battery rated storage capacity of the AGM batteries is 375 amp hours at a 20 hr rate. The charge controller can support a 30 amp input and any number of additional batteries can be added should demand increase. Currently heavier loads are running from generators as needed.

  This system uses two 12 vdc modified sine wave inverters; one 2500 watt 120 VAC for the house lights, small appliances, and electric tools. A second 5000 watt inverter provides 240 VAC for the well. Heating for the house does not use any significant electrical load and we do not normally run a refrigerator or freezer.

   This electrical system has cost about $2500 as a DIY project. The solar panel is rated at 25 years and the electronics are oversized and should last indefintely. The batteries are starting to show their age and will need to be replaced before long. I'm wanting to build more capacity into the system and upgrade the inverter to a 24 vdc split phase pure sine wave, so the timing for their replacement is coming at a good time. It is located in southwest Missouri and while not located in the sun belt per se, works suprisingly well.

Heating water

   One of the more energy demanding things right after pumping water is heating water. After a little research I came up with this configuration to heat water using solar only. After locating a solar water panel in Canada and the necessary heat exhanger, pumps, and using a standard water heater, I got this system up and running. I was quite suprised that it had a 30 degree F rise in tempature from a cold start in two hours; much better than I anticipated. The two circulation pumps run directly from the solar panel.

  I originally had the pumps running on the existing solar panels that charged the batteries. However, the pumps run more often than needed. That could have been because the electrical panels were mounted some distance away from the water panel and possibly voltage may feeding back from the charge controller powering the pumps even though the panels were not producing. To alleviate that, I mounted 12 vdc 15 watt solar electric panel on top of the water panel that supports the circulation pumps only.