Sunday November 22nd, 2009
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Passive Solar Vs. Solar Panels
Posted by Philip Higgs on April 30, 2007 - 10:34pm.
I did not, in fact, get an energy audit. Yet. But it’s in the works.
In the interim – and in the interest of planning projects, which is much easier than actually doing them – we had a nice man from the local solar installer shop come by and assess the solar potential of our little shack. The state-mandated rebates for going solar in Colorado are pretty sweet right now – 50 to 60 percent off the total system cost – so no harm in seeing what’s possible, right?
The process was pretty painless – about an hour’s worth of some dude walking around the roof with a measuring tape and a solar pathfinder, trying to figure out where the sun hits and when.
As I’ve mentioned, our electric load for the year averages out to about 750 kilowatt hours per month. That’s more than the Boulder average, but we’ve effectively got three units living in the shade of one electric bill – us plus two apartments. Considering each of those apartments has a TV, a refrigerator, a computer or three, and lightbulbs galore, we’re not doing so bad.
To get to a hundred percent solar, we’d need about a 6 kW system – equivalent to 31 panels lining our roof. That means 516 square feet of unshaded, south-facing roof space. The key word there is unshaded. We’ve got a decent amount of roof space, but we’ve also got a surfeit of trees. The trees are swell, of course – honey locusts and aspens and a snow crabapple or two.
Most of them sit on the south side of our house, where they offer some lovely summer shade, especially to our roof, which in the freaking crazy Boulder summer can get hot enough to fry an egg, hyperbole be damned. But sweet shade, unfortunately, means crap solar access. The cells that compose a solar panel work in concert – if you shade a few, the whole panel cuts out. So even a stray branch here or there is a problem.
The solution, of course, would be to trim the trees – just at the top, to reduce the shade hitting our roof and increase solar access. But I like trees. And the passive solar heating they offer our house in winter. And reducing the shade means increasing the heat that hits our roof, which increases the heat that enters our attic, which increases the seriously brain-deadening heat of midsummer Boulder that seeps into our house. Maybe that’s a small price to pay for solar power – the big swinging hoo-ha of green cultural cachet these days.
Anyway. The solar guy’s banging out a CAD drawing of our roof space with some potential panel layouts, and hopes to have an estimate back to me next week. I’ll keep you posted.
Air conditioners can be one of the greatest energy users, cutting down or trimming shade trees doesn't seem like a good idea! Even without AC, shade helps keep you cool, and of course trees are good.
It looks like you have some room for panels, will be interesting to see the CAD layout.
No AC for us. Not even a swamp cooler.
As for the trees, we'd only have to trim the very tops. You can see a strip of unshaded area along the roofline in that last pic -- we'd just be widening that.
Aren't there smaller PV arrays these days, like solar panels that are the size of roofing tiles? I thought you didn't need the ginormous solar panels anymore.
Also, did it cost you anything for him to come out and do the estimate?
Nope -- it was free.
There are smaller panels -- they're called BIPV, for building-integrated photovoltaics. They basically are solar shingles. Only problem is, they're crazy expensive, and much less efficient, something like 8 percent efficient (vs 20-odd for monocrystalline panels).
In the future, though, I want my whole house covered in solar shingles.
dajaszco brings up a good point, by trimming the shade trees your house will increasingly get hotter, but it's all for a good cause.
Anyway, as much as I would want to get some solar panels on my roof, I simply wouldn't be able to make the expenses upfront. But luckily it seems that I can go solar afterall, which is just delighful.
http://affordablesolarpanels.com/index.html?gclid=CPnOxJ2Q7osCFQzDYgodKlr_VA
Has anyone tried this out?
Where do you live? Are there rebates or tax incentives available in your state? You can check them out at dsireusa.org, which lists financial incentives for renewable energy by state; they can significantly lower solar install costs.
I've seen that CitizenRe project before -- basically, you rent grid-tied solar panels rather than buying them. I'm not convinced that renting solar panels is any more cost effective than buying them outright on a loan or credit card with a decent rate -- especially with the government-backed financial incentives involved. (And, to be honest, that ridiculous web site doesn't inspire a whole lot of confidence.) More about this on Thursday.
Ah I would in fact consider applying for another loan or a credit card, but I already have school loans and a car loan to deal with it at the time being. So that probably wouldn't be such a smart choice, for me at least. The website does seem a bit fishy, A few days ago I registered at CitizenRe to receive more info regarding the service though. Anyway thanks for the advice, I'd definitely love to get more insight on this alternate method of paying for solar panels.
good day.
http://renu.citizenre.com/index.php?c=1178076431
You should contact a local solar installer with a good reputation (check out findsolar.com) and have them do an estimate -- how many panels can you get, and what it will cost you after the rebates.
Then see what, if any, financing options they offer, and how much paying for the system will cost you per month. Compare that to what CitizenRe would charge you per month for renting panels.
Also consider how long you're going to be in your current house. Solar panels can increase the value of a home -- no (or low) monthly electricity bills mean an extra $100 or $200 a month that can go toward a mortgage payment.
I'm not much of a climatologist, but from what I'm told, it's caused by aerosols and particulates in the atmosphere, both of
which are either stabilizing or going down (thanks in large part to increased regulation) -- so global dimming is on its way out. Or so the word from the lab says.
At any rate, it's not something that's will greatly affect your solar panels -- at least not for a long time.
I have signed up for a system from Citizenre (http://www.affordsolarnow.com) and I think that this is a great opportunity for people who normally would not be going solar to have the option to go solar.
I have heard that there are something like 75% of homeowners that want to go solar but they won't do it because of the big upfront investment. But, if you make it affordable/doable for the "average" person then the chances are much greater that more people will go solar.
I realize this is a product that costs much less than a solar energy system but what about cell phones? When they first came out they were expensive, noone was buying them, now everyone has one. They get them for free if the sign up for a long term contract, this revolutionized the cell phone industry.
The same thing is true for satellite TV...you get your system for free if you sign up for a long term contract.
Something has to change because the traditional solar industry has not been able to make a dramatic increase in the number of homeowners that have solar systems.
This is not to say that they are not dedicated professionals but the traditional way of doing solar has not made much of an impact in the number of people that are using it at the homeowner level.
If Citizenre does not work, there will be someone else behind them and it's going to have to happen one way or the other. More people need to have access to going solar, this has got to be part of the solution.
Regards,
Erin
Second thing is, your argument is that in order for solar to become more widespread, it has to become more affordable. I agree. But locking people into long-term agreements isn’t going to make solar more affordable for them. If the CitizenRe model works, then solar will become much more affordable much sooner – at least for those folks not already locked into a cumbersome 25-year solar-panel rental agreement. What happens to those people, and those panels? The people have to give up a security deposit, as well as the money they’ve paid in rent, and then start all over again with new panels and new installation costs.
Another problem: Solar panels are typically carry a 25-year warranty, but they can last much longer than that. What happens to CitizenRe panels after the 25-year rental contract expires? They go back to CitizenRe. Whereas the house with purchased panels keeps powering away for another 15 years.
Finally, the financial incentives offered at the state and federal levels are making solar more affordable. (Which is, incidentally, why I asked readers to help urge Congress to pass the Securing America’s Energy Independence Act.) Again, here in Colorado, a $40,000 system will cost $15,500 after rebates. Yeah, that’s a big number, but it’s a smaller number than the cost of a new Hyundai. And people buy Hyundais all the time. How? They finance them. $15,500 spread over 25 years is about $52 a month. Interest will cost you another $100 a month. How much is your electric bill? How much is a 5kW system per month from CitizenRe?
I don’t mean to sound short, but I really disagree with the CitizenRe model.