So, lured by various trivial goodies (a nice steak dinner and a gift certificate), we got a solar power estimate for our little half-duplex.
A minimal build would provide 87% of our electrical needs, a maximal one would provide 131% (which would leave capacity for a future electric vehicle buy which is probably about six to ten years off when our current car, with only 54,000 miles on it after nine years is replaced and EV battery technology has improved), and the build we would most likely actually buy if we did it now would provide 107%.
It would require 8-10 panels on our roof and detached garage roof combined. The entire process would take about two months with one day of on site installation.
It would pay for itself in about 15 years if we paid for it up front (not including a battery backup for the house), but the economics are significantly less attractive if you finance it (they offered 8.49% APR financing). It would probably also modestly increase our homeowner's insurance due to the increased risk of hail damage claims (the better options are supposed to withstand 14 mm hail). This pricing is after a 30% federal tax credit that is not refundable, but can be carried forward.
Of course, it is also a hedge against increased electricity service rates (much like a fixed rate mortgage but for electricity), and would mean that our home would be powered with 100% clean, renewable electricity.
A whole house backup power battery (that Xcel could also tap into in some circumstances), with about 24 hours of power stored, would cost another $15,000, but with a roughly 80% subsidy (with the State of Colorado and Xcel energy paying for about 50% in addition to the federal government's 30% credit).
Our experience over the last twenty-four years in Wash Park, however, has been that power outages are infrequent and short, and so a whole house battery probably doesn't justify the expense even with an 80% subsidy. Depending on the electric vehicle we purchased, we could probably even use that for backup power.
We will probably not bite yet, because we have other more urgent home improvements to make (our range-oven, and our evaporative cooler both need to be replaced in the near future, and we'd like to kill the remainder of our lawn). Also, solar panel prices have been plummeting and it isn't clear if we are at the bottom of that trend yet.
Still, if I was building a new house, I'd probably include solar panels and a battery backup for the house. A maximal solar power installation would also be more attractive if we had an electric car and/or if we had a heat pump instead of natural gas heating.
In a new build, I'd seriously consider a heat pump (and better home insulation), an electric water heater, an indoor electric range, and an electric car charging station, to eliminate the need for a natural gas line entirely (although I'd have, at least, an outdoor gas grill and gas fire pit under a non-air tight gazebo fueled with small propane tanks).
Honestly, it is impressive how much it is possible to free yourself from fossil fuels and to have zero or near zero net energy consumption at the grass roots level.
Other observations
In the course of gathering information about that, we also figured out our household's total energy consumption expense (electricity, natural gas, and gasoline for our car) which is about $200 a month, compared to a $340 per month average in Colorado and compared to a significantly higher average for the nation as a whole.
About 14% of our electrical consumption is for seasonal cooling (an evaporative cooler and a ceiling fan). About 82% of our natural gas usage is for home heating in the winter (the balance is for a natural gas cooking range and natural gas water heating).
And, since the our household utility bill files were out, we also examined our water usage. The Colorado average is that about 50% of household water consumption used for landscaping (i.e. watering the lawn). In our case it is about 33%, since we have such a tiny lawn. Our water consumption is also well below average (as expected, now that we are empty nesters with a tiny lawn). Water for the lawn (at the higher summer water rate) costs us about $80 a year, which also has to be mowed, fertilized, weeded, etc.
3 comments:
"Depending on the electric vehicle we purchased, we could probably even use that for backup power."
In 7 years, most BEVs will be able to provide backup power. That is an 80 kWh battery. Which is huge.
Hum... we spent two long evenings with a solar power contractor. We were looking at a 12.5 kV system for our small (for Houston) 1600 sqf house. That would get us to 100% coverage averaged over the year. The cost was (IIRC) $37k cash up front and a 7-8 year payback period. Since my roof is 12 YO I would need to replace that as well at about $17-18k. Then I talked to a friend that just had solar install on his house. It took about a year from contract signing to 1st power. Most of the time in a cycle of inspections and waiting for some sort of interconnect permit. In the two years since he installed the solar on the 10 YO house it has had two roof leaks. The folks across the street from us put solar on their house and then moved up to a larger house. The new owners had the solar removed when putting on a new roof. Don't know how that works solar providers' contract. On the other hand my brother-in-law put solar on his house up ion Missouri; $27k for a 1250 sqf house. Their electric bills have been miniscule for the last year. In the end I didn't pull the trigger, but another 10-15% decrease in cost (i.e. 5 year payback) would make me jump.
The upfront cost before the 30% federal tax credit would have been $15,546 for us. Net of credits: $10,819. Our house has a little less than 1000 square feet on the main floor with two bedrooms and a full bath (at excellent trim levels) and a 90% finished, but not very nicely finished, basement of the same size downstairs (with one bedroom that is legal except for a closet and a 3/4 bath). Roof leaks are warrantied (in theory at least) for 25 years, but the risk of a roof leak is pretty high in our house as the house is 99 years old and its attic framing is somewhat "eccentric" to put it politely.
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