Past Week

This past week has been interesting. Sunday and Monday (a week ago) were cloudy (rain) and cool, and the power from my solar system was about half that of the sunny days. The rest of the week was sunny. In addition, the days are getting shorter, and that reduces the solar output some. We're using our space heater during the evenings, thus increasing our use of solar energy. So far, several days of sunny skies is enough to meet the demands of our house and the evenings of the space heater running.  Yesterday was a cloudy day, and the solar system only put out about half of the energy it has been producing. As a result, the power this morning from the grid was about 30 KWH more than the power of the solar system. I'm not worried, though, because the upcoming week is forecast to be sunny, and the solar system should get caught up before the rain that is forecast for Thursday. I have our furnace turned down to 64 during the day ad 45 at night. This should reduce our consumption of natural gas. In December, when the days are the shortest of the year, I'll probably have to turn up the thermostat higher to compensate for the reduced output of the solar system.

My first power bill came a few days ago. Instead of the average of $118 per month, my bill was for $99. Most of that cost came from October prior to our solar system going online. The next bill will give a better picture of how we're doing, dollar wise. It appears that Rocky Mountain Power reads my meter on the 3rd of each month, so I'll try to minimize the net difference of grid power and solar power at that time so my bill will, hopefully, be under $10. I'm paying RMP about $0.12 per Kwh (including taxes and fees), so a net difference of 10-30 Kwh won't amount to much. I've been told I'll pay a fixed fee of $7 each month to cover the cost of being connected to the power grid even though I get most of my power from the solar system.

Based on the reading I've done, the first priority of solar power is the house. Any power generated above that goes into the grid. Each panel has an inverter to convert the DC voltage from the solar system to 117 VAC used by the house. The inverters use DC for input, and I'm wondering if the solar cells would power the house in the daytime if the grid is shut down (I would throw the two breakers in the main line to disconnect the house from the grid. The solar system is wired directly to the breaker box in my basement and thus bypass the two breakers in the main line. I'm tempted to run an experiment in the daytime and throw the two breakers to cut power from RMP and see if the solar cells do power the house when there is no connection to the grid.