December 6th, 2011

Energy From the Sun

This time of year our upper ecoroof starts looking a little scrappy. It gets a lot of sun and is generally too hot and dry for anything growing up there to be very happy. So recently after talking with some of our neighbors who have been enjoying the benefits of their solar panels, we’ve begun to look into the possibility of installing a small array on our upper roof.

Its a fairly ideal space… Easy to install, never sees shade during the sunny months, so here’s some info about the process:

Does the Money workout?

Sort of. Lots of people will tell you that it doesn’t, and that depends on your threshold for payback time and what the incentives are in your state. We are looking at roughly a ten year payback and feel that ten years is pretty reasonable for something like this. ¬†We are looking at a 1.785KW array that will cover about a quarter of our total energy needs, and this has a total installed cost of roughly $11,500. From there we get an instant break from Energy Trust of Oregon of about $3100, so the out of pocket is $8400. After that, there is a federal tax credit of 30% ($2500) and a state tax credit ($2.10 per Watt) of about $3700, which brings us down to about $2200 of total expenses… Not actually that expensive in the end, but that initial expense is a difficult one to get through.

How is it Installed?

It’ll really just sit on top of the ecoroof inside the parapets, ballasted with concrete blocks.

What does this mean for the plants?

Strangely, even though with the plants and panels we would have two things up there competing for sun, this is a case where they each benefit from sharing. Portland State University has some interesting research showing that they plants benefit from the shading and consequently do a better job at stormwater management, and also help keep the panels cooler allowing them to run more efficiently and produce more power.

Why Now?

We have gotten on this path partly thanks to our neighbors, and partly due to an effort by a small group in our neighborhood to make our part of Buckman a registered historic district. The city of Portland has some policies pertaining to historic resources that are very unfriendly to things like solar arrays… Making them difficult if not impossible to site and adding a layer of review that can cost a few thousand dollars, making the payback time very unfavorable. If this goes through, it is a setback for sustainability in the neighborhood. And if we want to be producing any of our own power, we need to get on it before any of this has a chance of going through.


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