Comments on: Weekend Roundup: Solar for Renters

By: Nathan

Nathan — Tue, 25 May 2010 20:48:58 +0000

Over at instructables.com there is an instructable on how to make a “solar panel art sculpture” type thing, where they use cheaply purchased broken panels and conductive mesh and conductive glue to create what solar panels to light or power the sculpture. I would think one could take this concept and apply it to regular curtains with a little bit of handiwork. Our windows are used for lighting as well, but at the same time during the day we do keep our curtains and blinds drawn and still have adequate light. The nice part of this design is I think it would draw more from ambient light than from direct sunlight. For example, PV curtains would generate a fair amount of power in northern states during the winter (light reflecting off snow and ice will hit the windows, while the rooftop PV panels make no use of it). The way I look at it, if you’ve got a window you keep the curtains drawn most of the time, it wouldn’t hurt to see if you can’t eke out a little bit more power, can it? During the summer the blinds are drawn to help keep heat out, so then the blinds/curtains would serve a dual purpose, insulating and helping generate even a little power to help offset the AC/Central Air power drain.

I figure something’s better than nothing, right?

By: Leonard

Leonard — Tue, 23 Feb 2010 20:11:51 +0000

Scott:

Thanks for this, I forgot that there was a whole chapter on energy in the RUST book.

By: Leonard

Leonard — Tue, 23 Feb 2010 20:10:30 +0000

Your point about solar energy generated vs. heat-loss is spot-on, and really well taken. I guess I’m wondering about contexts in which folks (particularly renters) are working within certain existing constraints:

*I know a lot of the readers here live in older buildings that still have old windows with untempered glass, which they don’t have the authority to replace. What about this sort of situation? Are these old windows low-e?
*Buildings that were not built to passive solar specs and have large banks of south- or west-facing windows, could they still be appropriate?

By: Jen

Jen — Mon, 22 Feb 2010 19:50:53 +0000

Photovoltaic curtains are a BAD idea, because while all glass will cut solar gain some (which is why solar PV panels use low-iron glass to minimize energy loss) most modern windows use coated glass materials called low-e…i.e., a low amount of solar & UV energy penetrates them, making solar curtains almost completely useless. UV is the part of the spectrum with the highest energy, and is the main target of low-e glass. It would be a waste of money for the consumer, and highly inefficient by any standards.

Triple glazed windows with photovoltaic blinds might be a better idea, with a low-iron glass on the outside, and low-e glass on the inside. These would be great in office buildings with west-facing glazing (which is the main place you’d want to draw the blinds while the sun was shining)…otherwise, you have to ask yourself what sense it makes to have a window if you’re going to draw the blinds. For the miniscule amount of energy solar makes compared to the heat-loss of a window…glass has an R value of 2! Glass should be used for lighting, and we should insist on buildings built for passive solar heating and cooling.

By: scott

scott — Sun, 21 Feb 2010 18:55:02 +0000

in the DIY / zine literature (think “Guerilla Greywater Girls”) I’ve seen designs for many types of passive solar heaters, but keep in mind many were designed for those of us in the southern united states.

One that I remember well was an air heater. This is a two-layer frame you could install into a window just like the picture above. the frame would be held in place by a closed window, like a modular air-conditioning unit, and would be tilted downward, to match the optimal angle of the sun, given your latitude.

The scrap window frame itself was built-out with a scrap window case on the top, plywood on the bottom, hollow in between. insulation wouls be optional, more necessary in colder climes. mounted between these two sides was a piece of black [material], exposed to the light coming through the window. a gap is left in the far end of the middle layer for air circulation. The sun, shining through the window, heats the air between the window and black material, which rises into the home. Cold air is sucked into the lower chamber, which circulates to replace the heated air that has risen.

The design ideas in this literature tend to source materials out of trash, an added benefit to those of us worried about preventing waste from landfills and waste of production and maintenance of hi-tech gadgets.

cheers

p.s. this book,
http://www.radicalsustainability.org/rust/preview
which should be required reading for your weblog readers, includes different methods of passive solar cooking.