A Roof Full of Energy

We've spent the last few weeks waiting for Xcel energy to come and trench in new electrical service to the house from the alley. We wanted to replace the old overhead wires (they tend to get burned when your neighbors garages start on fire or come down in storms) with buried cable. Even though we've been on the schedule - they never seemed to make it to our house to do the work. This has cause multiple delays and rescheduling of things and has generally been pretty irksome.



The crew of 6 showed up today - 5 guys to watch 1 work - and started in on the task, their brand new trucks at the ready. I tell you all of this just because in my heart, though I have been completely aggravated about their adherence to schedule - I am secretly amused because I know that in a few days we will be selling them energy that we've created on our rooftop through our solar pv array.




A view of the solar thermal panels behind the solar pv panels. The white roof membrane helps keep our house cooler in the summer by reflecting unwanted solar radiation away from the house. This will get covered up by our green roof system this fall.

With the help of Mario Monesterio form Best Power International, we've created a little energy garden on the rooftop. We have both a solar thermal system for making hot water for the domestic water needs of the house (washing dishes, clothes and bodies), and a solar photovoltaic (pv) system to make electricity. Whenever the sun is shining , we'll make electricity for our own use. And, because we decided to tie it into the utility grid, whatever we're not using we'll be selling back to the utility company and watch our meter spin backwards.

We have the pv system also connected to a battery back-up system so that we can continue to have power even if the power lines go down in a big storm (not ours of course, because they're buried). This is a sweet little system that even Mario is jealous of. He must be at least a little proud of it because he brought a few folks by the house yesterday to look at it. Both the solar thermal and solar pv systems have a lot of nice gizmos and features that allow us to do different things including data tracking and energy production, use and efficiency monitoring.

Okay - so how much did we pay for these systems?

The solar thermal system (2 panel) was just over $6,000.00 (not accounting for federal tax credits) and features a payback period of about 12-14 years.


Leon the builder and Mario the solar guy discussing where to buy white socks.

The solar pv system (1.5 KW) cost just over $16,000 (not accounting for State tax rebate of $3,000 and the additional federal tax credits - roughly another $2,000). In the end, the pv system should pay for itself in about 16 years -perhaps sooner if energy prices continue to climb. Solar energy is still more expensive per kwh than buying regular old electricity from the coal burning plant down the road - but with better social and environmental karma.