Six months energy data

Happy 2012!

Here's two graphs for July through December, showing our usage vs. PV production, and where the energy is going. In the first graph, one can see the usage increasing as we begin to use the heat pump at the end of October, and the solar electricity is dropping off as the days get shorter and cloudier. In December we go from being a net energy exporter to a net energy importer. Only by installing the woodstove will we be able to be energy exporters each month, which is my goal. Our shortfall of 183 kWh in December is caused by the 238 kWh the heat pump consumed.

In the graph below the energy usage is broken down by end use. Other includes the composter exhaust fan, lights, wireless router and modem, computers, and small kitchen appliances, as well as any power tool usage. I'm a bit confused why there are peaks in Other in August and October. Oh wait, in August we had an influx of guests, which also shows in the DHW energy usage. Maybe on MV that month should be AuGuest :-) October, that's still a mystery... One can also see the increase in cooking energy in November and December. Less fresh food straight from the garden, plus holiday cooking and baking, are the reasons. R/F are the refrigerator and the chest freezer, and the change in their energy consumption is addressed in this post.

I think we have a strong chance to achieve net zero for our first year. The utility meter read 100,137 kWh when the PVs came on line in early June, and it read 98,448 this morning. Since June 9th the PV system has generated 1,689 kWh more than we've consumed. I can imagine our January and February usage cutting that surplus in half, yet sometime in March I expect we'll get back to net exporting. Stay tuned...

 

Comments

[Ed Davies]

What's “R/F”? Refrigerator and freezer?

[Marc Rosenbaum]

Yes, R is the 18 ft3 refrigerator with top mount freezer, and F is the 15 ft3 chest freezer in the basement.

[John Rockwell]

Is the DHW increase related not to actual usage but to the lower basement temperature and therefore greater delta T?

[Marc Rosenbaum]

The increase in DHW energy is caused by lower basement temperatures and colder incoming water - see the previous post entitled Seasonal Changes in Loads.
http://blog.energysmiths.com/2011/12/seasonal-changes-in-loads.html

[Ted Inoue]

Marc, great to find the blog of a fellow energy-geek (and biker). I'm jealous of your net-zero ability. I'd put up panels in a blink but I'm surrounded by people who still don't appreciate the beauty of a roof full of panels. :-)
Your total consumption is amazingly low. I've been trying for years to get my base consumption down but never was able to come close to that because of some of the luxuries that I've been unable to ween the family off of.

[Marc Rosenbaum]

We have a saying here that I borrow from Andy Shapiro - there is no such thing as a net zero house, only net zero families!