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.

Electrical

   The photo at the left is the original equipment in the mechanical room that has supplied all electric power to the house and the well for several years. The solar electric power was 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. It is located in southwest Missouri and while not located in the sun belt per se, works suprisingly well.

   One note on modified sine wave inverters which I have at present, while they work, they make some things noisy with motors, like microwaves and ceiling fans, and some electronic devices will not work with them. While cheaper, they are somewhat annoying in the sound department.

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 40 gallon 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.


  I originally had the thermal coolant pumps running on the existing solar panels that charged the batteries. However, the electrical panel was some distance from the thermal collector causing to pumps to run when there was no sunlight on the thermal panel. To alleviate that, I mounted a 12 vdc 15 watt solar electric panel on top of the thermal panel which keeps the pumps and thermal panel in sync with available sunlight.


   This is my final configuration for my 2018 upgrades, new wet cell batteries with a 740 amp/hour capability to replace a couple failing AGM batteries. Two of those AGM batteries are still in good shape and I'm storing excess energy from the hot water system on them as a backup 12 VDC source. I added another 12 VDC 170 watt solar panel, to double my recharge current and both panels can be reconfigured to a 24 VDC system. I intend to replace the two inverters with a single 6000 watt pure sine split phase inverter in the future, which requires 24 VDC and should reduce my standby current and provide some benefits of a pure sine waveform.

   So far I have been impressed with the solar hot water system, these newer hot water tanks retain heat well and so far the system has supplied all the hot water we have needed. Winter may be another story and may require a differential controller, which I have but not installed yet.