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Saturday, January 12, 2013

A Great Investment


The numbers are in:  we are doing way better on the return from our solar PV system than we are at the bank.

Here are the results in Steve's own words:

"We used 4638.92 kWh of electricity for the 12 months November 2011 through November 2012. We produced 5261.92 kWh in the same time period, meaning that our solar system covered all of our electrical needs.

If we had needed to buy the 4638.92 kWh from PGE at 13.56 cents/kWh, it would have cost $628.81. Subtracting out our connection fees and taxes for using PGE as our battery, the value to us is $505.69.

Our return on investment is the value of the electricity divided by the cost to us of the system. $505.69 / 7492.5 = 6.75%

We will not truly know if our system was sized correctly until the end of March when any excess credits are transferred to the low income assistance fund."

We could have opted for the program whereby our local utility would cut us a check for the excess of what we produce, but that would have meant a minimum of a 6 kWh system, and we would have needed a larger roof for that which would mean a bigger house, which would have resulted in a higher mortgage payment, which would have pretty much defeated the purpose.  I am just fine with what we have- we pay $10.26 a month to be hooked up to PGE, which we use as a giant battery, and any excess produced will be donated to the low income assistance fund at the end of PGE's period in March.  I doubt we would go off grid until we're out in the country (which is back on the table - Yay!) at which point we'd be working with a low-voltage system anyway.

As it is, our electricity costs for the entire year is only $123.12. If we're careful and continue to at least use the same or less electricity  than we produce, they will always be only $123.12 for the entire year, until such time as PGE sees fit to raise the cost of being connected to the grid, of course, which will reduce what goes to the low income assistance fund.

I wish I could do that well with the natural gas bill.  The only thing that makes that spike is if Steve brews beer.  Last month's gas bill was a whopping $31.13 and I'm sincere about whopping because the month previous it was in the $25 range.  In the summer we use almost zero natural gas because we don't cook indoors and that is the period when the solar water heater is rockin' the hot water.


By the way, this is all happening in the Pacific Northwest, where the only thing thicker than the persistent mist that falls almost three quarters of the year is the abundant moss growing on everything.

If we can do it, you can do it, so if you're thinking about solar and can afford it, do it.  Part of what made this work for us is the fact that we saved up and paid cash for it, but if your results were the same as ours and you borrowed at 3% for it, you'd still be ahead.

It would still be a great investment.

5 comments:

Miriam said...

THANK YOU for being brave enough to give this a try and then sharing your experience with us! I am speaking in particular as your neighbour in the Pacific northwest, because I have always been sure it wouldn't work here.

I'm still not sure it would work on our particular property because we are surrounded by trees, but your success is enough for me to start investigating this more seriously.

Paula said...

Yeah, trees are an issue. The neighbor to the east of us has a tree in her front yard that came up in part of the evaluation that the solar company did- they decided that it would shade only one small portion of the panels (like 4-5 of them out of 18) for part of the year, so it was still a go.

If you have a solar outfit out to assess what can be done, they may advise you to take down some trees. That could still be a good idea for both passive solar energy for the winter and more sunlight for your garden, but only you guys know what the aspect of your house is on your property and where your trees and garden are.

Steve and I also use a lot less energy than the average joe- I had figured out that we use on average only 13.5 kWh per day. Knowing what you use should be part of what you use to figure out if solar is for you.

If you have a stream on your property all year, you could think about micro hydro, though.

Paula said...

We used Solarworld panels and Enphase microinverters. These panels are made locally in Hillsboro, OR, but Solarworld is a German company who really seem to know what they are doing.

The advantage of the microinverters is that it makes each panel independent of each other, and the other advantage is that they are sending AC off the roof, so we don't require shielding to bring DC to a central inverter. Steve says the microinverters did not cost any more than a central inverter and that if you add in the monitoring and tracking which came with them, they are probably less. We're connected by a device to the internet to their software so that we can monitor what we're producing at any given time.

Tamar@StarvingofftheLand said...

Paula -- How great is that? To generate more than the electricity you use is a wonderful thing. And I'm guessing, if you sell the house before you recoup your costs, you'll recoup them at the sale. I'm thinking a proven $10/month electricity bill is a real asset. Nice work.

backyardfeast said...

Paula,this is awesome; thanks so much for sharing your details. The 13.5 KWH/day is amazingly low. We've gotten ourselves down to about 18.5, which we're really happy with so far (we're all electric here, no gas to the property), and have been starting to think seriously about solar in the next few years. It's always good to hear that you can still use solar effectively even in our gloomy PNW winters. Like Miriam, we're farther north, but that also means longer days in the summer...

I'll have to read up on your solar hot water heater too!