Mar 132014

I’ve been monitoring my solar power and P&GE bill regularly, looking forward to the next bill. I know, funny that I’m looking forward to my next electricity bill. The billing period closes on the 14th and it’s looking like another 20% normal month– this because of longer, brighter days and more cloud cover– which is to say the bill would have been even lower if we had not had the cloud cover and rain. (Not that I’m complaining, California is suffering from drought conditions. We need every drop.)

For March 11, 2014 we produced 27.4 kWh

With a Peak Power of 4.13 kW at 1:35 PM.

The power production graph looks like this:

Since these are 15 minute intervals, the peak power is around 1000 kW per 15 minutes (4 kW per hour). Each horizontal bar represents approximately 250 kW production. The grade in the morning is longer but not as robust as the afternoon grade. This is because the panels are positioned to take advantage of mid-day and evening sun.

The afternoon slope is shorter and steeper because behind us we have taller neighbors and therefore more obstructions restricting energy production.

I still have space on the roof towards the front. If for some reason, somehow, I ended up needing to install more panels, I could probably eek out another 1 kW or so (taking advantage of the morning light).

The power consumption graph looks like this:

  • 5 AM is computer and station keeping on all appliances.
  • 6 AM is station keeping + computer + heater. (70 is comfortable. I turn it on in the morning to make the house comfortable and then turn it off.)
  • 1 PM is peak production with only station keeping + computer. (Consumed about 800 kW, produced about 4.1 kW. Net credit.)
  • 4 PM, I probably had left my computer on and went to watch TV. (Catch up on one of my DVR’d programs.)
  • 6 PM is dinner prep, plus probably some laundry and TV.
  • 10 PM is probably plugging in the hot tub (I drained and re-filled it that day, so it had to heat up the fresh water which consumes a lot of energy apparently) + dryer on high.

Total consumption for the day was (27.4 kWh produced + 15.6 kWh more consumed, equals) 43 kWh for the entire day. Definitely higher than normal.

Without Solar that would have been a very very expensive day (because we would have been into Tier 4 pricing already). As it was, it was only $2.42 (We entered Tier 3 prices on Mar 7.)

Total (estimated) electricity bill for Feb-Mar is only $60. (Not counting gas charges.)