Cheap DIY Solar at $0.09 per watt!

The following post was written by Eric Sandeen and can be seen on his blog here.

There are a lot of silly DIY solar scams out there, but here’s the real deal.


  • An average electric dryer run uses about 3.3 kWh of electricty
  • An average home might run 150 dryer loads per year
  • This equates to roughly 500 kWh per year for drying clothes

Let’s say you wanted to “go green” for your laundry drying needs by “going solar.”  How much solar PV would it take to dry this much laundry?  According to the PV Watts website,  a 500W (0.5 kW) PV system would yield about 612 kWh in a year here in Minnesota.  That’s a bit more than the dryer is taking, but panels are commonly 230W these days, so let’s round down to a 460W system, and say it’d net somewhere around 500 kWh in very round numbers.

Hm, or you could just not use your dryer, and hang your clothes outside!  How much might that save vs a solar setup?

Ok, you can’t hang up clothes in a Minnesota winter.  So let’s cut the potential in half – 250kWh/year of clothesdrying in the summer, and this would take about a 230W solar array to compensate.  Let’s say $8/watt for a solar install – really, for a small job like this it’d be more, but again, round numbers – this leads to about $2000 for a panel, inverter,  installation, and hookup.

Or – you could spend about $20 on a couple of retractable clotheslines, and have the same net effect, plus the zen-like serenity attained by taking a little time out to do a simple task like this outdoors.  $20 for the equivalent utility of 230W of solar … at $0.09 per watt!

(This really is a fine example of why any good solar installer will tell you to do everything you can to conserve first – it’s much, much cheaper!)

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You can purchase a fairly inexpensive clothes hanger from Costco or order it online for $30. In Winter, Summer or any season, you can easily dry all shirts, pants, underwear, socks, dresses, etc in an area that is just 3 foot by 5 foot. In winter, with the heater on, the clothes will dry in record time.
Another idea is to erect an inexpensive plastic shelter (think tent but very transparent), and have the clotheslines placed within it. You'll spend a few bucks getting the shelter, but that would be way less than the PV panels.
Most solar panel systems produce well over 500kw hours per MONTH... and can pay for themselves over about 7 years... then its free for for the next 43 (unless you break them of course). Sure its expensive up front but what good investment isn't. Your numbers are pretty bad and i would suggest you better research your topics before you talk about things you are not informed about.
Guy, thanks for your comments. I am fairly familiar with residential solar economics; I have a 2.53kW array on my home. Gross cost (1.5 yrs ago) was about $17k. With generous rebates at the time, my out of pocket costs were around $5k. It made just over 3MWh in the first year, worth about $310. Depending in what utility rates do, yes, payback will be on the order of 10 years. But I think you missed my point; solar is expensive enough that conservation and efficiency looks really cheap in comparison. If you have a goal to cover 100% of your use with solar, you can work both sides of the equation. Installing an extra 500W of solar to cover an electric dryer is much more expensive than installing a clothesline, and the effect on your final bill - and on the environment - may be about the same. (Side note, it is unlikely to have a maintenance free array for 50 years. The panels wil likely keep producing, but the inverter will need replacement at least once in that much time). -Eric
ckmapawatt's picture
Eric, What about winter? Isn't it hard to dry your clothes outside then?
Hi Chris - well that's why my back-of-the-napkin sketch compensated for winter - "Ok, you can’t hang up clothes in a Minnesota winter. So let’s cut the potential in half " - but people have pointed out that you can in fact dry clothes in the winter, indoors or outdoors. Indoors, I really can't in my home - we have moisture problems and this would probably make it worse. Others, though, probably have dry air in the winter and a drying rack might actually help! Outdoors, sublimation [1] actually works - If you hang up clothes, they will freeze, but they will eventually dry. I'll admit to still mostly using the dryer in the winter, though. [1] "The process of transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase" - cool eh? also has a post up on other alternatives to dryers -
Did you confuse watts and watt-hours? By my somewhat rusty math, spending $20 for clotheslines and clothespins gains you the energy equivalent of 500 kWh, the amount of energy you'd save by hanging clothes outside instead of running your electric drier. So that works out to 20/500 or 1/25 of a $/kWh, which is $0.04/kWh. This compares favorably with typical electricity rates of about $0.12/kWh. (And ignores the fact that you've switched your energy source from sunshine captured about 300 million years ago (coal) to that day's sunshine.) Your math would produce a "not so cheap" deal --for 1 hour of juice-- of $0.09/Wh or $90/kWh.
Solar installs are often priced at a per-watt price (for the peak/nameplate capacity of the array), so my $0.09/watt was intentional. I wasn't calculating the price of the electricity you get, but the price-per-watt to avoid the solar panels you didn't have to install to run your dryer. :)
DC powered fan can use air in house to dry clothes in winter... In less than 6 hrs. BONUS adds humidity.. VERY cheap to run, and can use 12 volt solar panels.. Terry cloth towels, robes, blankets and jeans are about the only thing that are not worth drying outside in the winter.. Thick, heavy, tightly woven material might take 2 or 3 days...


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