Nov 22, 2019: Energy Positive Success

We’re making steady progress on the interior renovations to the old cottage next to the Greeny Flat. We were a bit distracted for the last couple of weekends due to opening the Greeny Flat for the Arts Trail which turned out to be a really nice thing to do. On all four days we had a steady stream of the nicest people you could hope to meet. Cintia sold quite a lot of pottery and we made lots of new friends so it was well worth the effort. Now I’m back to the renovations. We’ve hung the gyprock and are ready to plaster and paint. Then we’ll be installing the new kitchen which we ordered last week and the new flooring which is also on its way. Once we have the new kitchen up and running we’ll be able to take out part of the old kitchen (the rest will stay and become a sort of mudroom-come-butler’s-pantry) and close in a small room for a second toilet which will be handy in a four bedroom house.

As reported in our Newsletter back on August 30th we have had 5kW of solar panels installed on the roof and we are now fantastically energy positive. Since the new meters were installed in early September we have imported 450kWh of electricity and we have exported 1280kWh. That means we have put almost three times as much power into the grid as we have taken out and we’re thrilled to bits.

Obviously this is a good time of year for solar. It’s been cool and sunny and we haven’t needed to run either heating or air-conditioning (not that this house will need much of either now that we have completed all the energy retrofit work) so our solar production is up and our energy use is down. But we have been charging our Plug-in Hybrid Electric Outlander most days and it looks like we’ll be well and truly energy positive over a full year which is a great result for what started out as an old fibro cottage.

Below is the monitoring results for our best day so far which shows that we produced 36.46kWh or solar power which is very impressive for a 5kW system.

Monitoring results for our best day's solar production so far.

Monitoring results for our best day’s solar production so far.

You can also see that we consumed 10.85kWh and a lot of that was for charging the car. I have circled the times when I had the Outlander plugged in. I usually try to only charge it during the day but if I know I will need it in the morning I will sometimes charge it late at night. I try to wait until after 9pn to plug it in because that is when the evening peak has passed so my charging the car won’t put any further stress on the grid.

What the monitoring doesn’t show is our off-peak water heater. I wrote about this at length in our Newsletter back on October 18th. I won’t go into the details again here but, suffice to say, our Enphase monitoring system is not configured to keep track of the electricity we use for off-peak water heating. I was going to try to get Space Solar to reconfigure it so it would show the off-peak but I’ve decided that the better solution will be to take the water heater off the off-peak circuit and put it on a timer to run during the day when we have all that excess solar power.

Meanwhile we continue to monitor the Greeny Flat which we started doing when we moved in back in April 2014. So it’s been five and a half years now and I’m very happy to report that over that time we imported 8107kWh of electricity and we exported 19424kWh. So we put about 2.4 times as much power into the grid as we took out! Given that one of our original goals was to make a house that was energy positive (i.e. produces more power than it uses) we can safely declare that the Greeny Flat Experiment has been a resounding success!

Another one of our goals was to try to use as much harvested rainwater as town water. So I’m happy to report that, over the last five and half years, the Greeny Flat has used 226167L of tank water and only 109168L. That’s almost exactly twice as much rainwater as town water. So the Greeny Flat has met or exceeded our expectations in every way.

Also worth noting in regard to the solar power system is that, so far, it has produced approximately $3700 worth of electricity (that’s about $673/year). At the time we installed it the cost was $4299 for a 3kW system (they’re cheaper now). So our simple Return on Investment has been about 15.7% and, by this time next year, the system will have almost paid for itself.

You beauty!

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>