When sizing up what it costs to add solar panels to your house, someone will inevitably say “it’ll take 20 years before you’ll get your money out of it.”
That may be true, but what do you have to show for twenty years of electric bills?
When sizing up what it costs to add solar panels to your house, someone will inevitably say “it’ll take 20 years before you’ll get your money out of it.”
That may be true, but what do you have to show for twenty years of electric bills?
The “20 years” argument is a red herring. In theory, you could finance the price of the solar installation with any reasonable loan. Instead of paying your electric bill each month, you pay the loan (which, if appropriately structured, would cost the same or less as your electric bill would have).
Then, in the present tense you are reducing fossil fuel utilization, and helping drive the production costs of solar down so future consumers can get it cheaper. At literally no cost.
In the future tense you get free power.
If my home weren’t in such a shaded plot of land, I’d have solar panels right now on my roof.
You write:
“in the present tense you are reducing fossil fuel utilization”
This is not necessarily true. Photovoltaic panels do produce energy, but it requires an investment of energy to manufacture the panels. While it is difficult to precisely account for this invested or embodied energy, some people put it only slightly over 1:1. That is, each watt that was used to manufacture the panel will be repaid by approximately 1 watt produced by the panel over it’s lifetime.
So, by installing photovoltaic panels you are not reducing fossil fuel utilization, you are simply consuming 20 years worth all at once to create the panels. After 20 years the panels will (most likely) still work, but they’ll have degraded and will continue to do so over the rest of their useful life (how much ‘free’ power this provides is hard to estimate, but it will be substantially less than what was produced during the first 20 years).
If you are in a remote location and cannot get electric power service then photovoltaic panels are great, from an energy accounting standpoint it’s like buying few decades worth of power and stuffing it into a form that you can take with you.
From an environmental standpoint it’s not such a great deal, there is large initial energy cost and only a very small payback that takes many decades to realize. It also (for non-trivial or traditional use) requires either lots of support hardware (batteries and electronics) or a grid-tie system. Depending on the policies in your area a grid-tie system may require the power company to maintain the baseload capacity to service the connection whether you use the service or not (kind of like wind generators, each MW of installed wind generation capacity requires an installed MW of generation capacity that can pick up the load when the wind isn’t blowing).
From both the environmental and financial standpoint it makes much more sense to first reduce your energy requirements as much as possible. This allows you to continue using existing infrastructure that use high EROEI fuels and also reduces the cost. Once you’ve minimized energy usage you can still move to PV if you want, but to supply your reduced demand you can buy a smaller system.
Thanks for that great analysis of an investment in solar. The technology is changing so quickly with solar (panels becoming far more efficient) that its laughable to think how a 20-year-old set will compare to the then-current models.
I suppose wind generation is the safest bet, providing you’ve got a good supply of wind. The technology is more stable and certainly more cost-effective.
Batteries are still made from some of the most toxic chemicals on Earth, which is another thing to consider. One day they will wear out and require disposal. Yuck.
Hmm. Is it unfashoinable to become a Luddite?
I have a solar powered calculator.
Seriously, I like your idea of using the thermal/solar energy in your attic to heat your water heater.
Yes, solar thermal is very cost-effective, far more than solar cells. Thermal also has very little impact on the enviroment, either in manufacture or disposal (no batteries). If waste heat in the attic can do it, awesome. If you’re got a panel on the roof, even better!
I’ve always been a proponent of using these hidden sources of heat or cooling, whether its adding solar or just making good use of existing landscaping. It’s clever engineering!
Mark:
As you may or may not be aware Ed Begley (the actor and enviornmentalist) has a new show on Home And Garden TV (10pm Sundays, thank you PVR!) that highlights Ed’s living green philosophy (and how it can be humorously at odds with that of his wife). Anyway, the show is really interesting especially with regards to Ed’s solar power. He has fixed panels on the roof as well as a “sunflower” panel that follows the sun over the course of the day. The house is also small by hollywood standards (do more with less) and it goes on and on.
The show is interesting because it really points out that living green is possible; the solar powered outdoor stove is one of my favorite gizmos thus far. There are also lots of shots showing the battery packs that store the solar as well as Ed’s little EV SUV (why did Toyota stop selling these?)
Anyway, it is a good show. I’m going to build a compost heap in the back yard this weekend or next to kickstart the whole green living thing I’ve been talking about for so long.
My next house, if I ever purchase one, will have both active and passive solar.
Cheers.
You might be interested in this free ebook:
http://www.builditsolar.com/Projects/WaterHeating/ISPWH/ispwh.htm
It gives some history of solar water heaters and a bunch of good information about how to build practical heaters.
I’ve been trying to think of ways to do a solar hot water heater for my home in the suburbs where people don’t like such things. I’m considering maybe something built into the attic with a skylight-like panel opaque to people but still effective at collecting heat. That would probably be effective and attractive, but also expensive and possibly something I’d have to get a building permit for. Easier might be just roof-colored hose installed in unobtrusive runs through which I could pump the water. Maybe worth experimenting with anyway.
There is a lot of battery research going on right now with the aim of producing something that can be used to power EV’s. Since that would obviously require an enormous number of batteries some of that research is focused on making non-, or at least less-polluting batteries. Hopefully within several years we’ll have reasonable batteries that are environmentally friendly.
I’m particularly interested in EEStor’s capacitor battery system, although I’ve heard from some people that using a capacitor as storage system for large motors is a terrible idea because of the energy losses (one person figured a theoretical upper limit of 50%). They perhaps are making some naive assumptions about how it would be used though.