Energy Report, September 2010


Solar electricity produced: 498 kW h (16.6 kW h per day)
Electricity consumed: 379 kW h (12.6 kW h per day)


Our solar electric production dropped 27% below what we produced last month, mostly due to cloudy weather. Meanwhile our consumption rose by 20%, so for September we only produced 1.3 times what we consumed. We're still a net energy producer and cumulatively we've produced about twice what we consumed, but as we expected the ratio is less favorable this time of year.

Toward the latter half of the month as outdoor temps started to drop, we raised the upper temperature limit on the heat storage tank so we could start using it for heating the house. As you can see the tank temperature climbed back to its 140-degree upper limit. We didn't need to use any of this heat for space heating in September, as the passive solar and internal gains were plenty to keep us warm on cool nights.

The graph below shows the temperatures outside (red) and inside the house (blue), recorded each morning and evening. As you can see September marked a transition from cooling season to heating season, but for the most part the house stayed comfortable all on its own without any active heating or cooling except for a couple of unusually warm days late in the month.


This page was updated on Wednesday January 11, 2017