Subject: Re: Solar Ovens
Definitely give it a try. It's really fascinating.
The one I made was one of the really simple cardboard ones - just a
box nestled inside another box that was an inch or two bigger all the way
around, with crumpled newspaper filling the spaces between them. I glued
foil to the inside of the inner box, and to the inside of the flap lid of
the outer box. I used a piece of coat hanger as a lid support, slapped
onto the side with a piece of duct tape. I rested an old window pane on
top for the glass. Inside, I placed one of those matte black round
stovepipe caps (used for closing off the end of a stovepipe as the
black-body absorber. I was getting temps in there hot enough to boil
water in a pint Mason jar. I put an oven thermometer in there, and the
highest temp. I witnessed was about 230F. The whole process, from saying
"gee, I wonder how well this works" through building it to boiling water
was about two hours. I used it to reheat leftovers for the rest of the
week.
Since then, I've been planning on building a better, more permanent one,
with a removable, enameled blackbody (a turkey roaster pan would be
great, but a similar pan in rectangular shape would be even better) and a
tempered glass top. I'd also splurge and make a metal reflector patterned
after the SunStar. Also, fiberglass insulation would bring it up to baking
temps. You can buy ready-made sun ovens that can easily bake several
loaves of bread at a time, but they cost $180-400 (or more), and besides,
part of the fun is seeing if you can scrounge up all the parts for free :)
Cheers,
Andy Evans Homestead Mailing List Administrator
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White Sulphur Springs, WV USA E:3 G:3 N:2.5 L:1
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From: "Couvia, Susan" <SCouvia@tchmail02.tchden.org>
Date: Wed, 14 Aug 96 12:59:00 PDT
Subject: Re: Solar Ovens
>They all look like relatively simple weekend
>projects, but I imagine the performance varies widely between designs.
I
>thought the Nelpa design looked very useful, but perhaps one of the
panel
>cookers would be a better first project. I was wondering if you had a
>recommendation for a favorite design?
(Yea, I know, you asked Andy, but I thought I'd jump in and answer
anyway!)
I built the Reflective Open Box cooker about a month ago, and finally
tried it out last weekend. It works well for me - I was out camping, and
my usual method of cooking while camping is while hiking I also forage
for wild foods. With the solar cooker, I just went off on mini-hikes, and
whenever I came back to camp I put whatever I found into the cooker, and
ended up with a nice stew. It took about 5 - 6 hours of cooking time, and
occasional adjustments to follow the sun.
The cooker only took about 3 hours to put together, and it is completely
collapsible, and light weight. One reason I chose the open box design is
that you don't have to have a piece of glass as you do with the closed
oven types. The only materials are a cardboard box, foil, and glue.
Susan
city house in Denver
70 acres near the Wyoming/Colorado border
------------------------------
From: Andrew Evans <aevans@cais.cais.com>
Date: Wed, 14 Aug 1996 15:16:16 -0900 (PDT)
Subject: Getting into solar the easy way
Hi folks -
The UPS man showed up this afternoon with my new toy - a Ryobi cordless
24v lawn mower, and a kit from Real Goods that converts it to solar. The
kit is just a pair of small self-regulating solar panels and a few wires
and connectors that allow it to hook up to the mower.
We were talking earlier about rigs for experimenting with solar - well,
this is a really good one. Though I also have a bunch of heavy-duty
photovoltaic gear for the house, this is a great, inexpensive way to try
out solar power and put it to a practical use at the same time. You can
buy the mower locally from your nearest big hardware store (it's a
commonly-available model - Ryobi BMM-2400, and I think some other
manufacturers sell it under their own names (Black and Decker?)), or
order it from Real Goods (probably more expensive). The solar kit is
sold separately anyway, and it goes for $199. The mower is itself a
highly-regarded, well-built tool, and the addition of solar makes it even
better. It will run for about 1 - 1.5 hours on a full charge, and with
the solar rig, is fully recharged in about 3 sunny days. I've already
taken it for a spin (it came from the factory fully charged) and it cuts
beautifully, and is incredibly quiet (it is almost as quiet as the
hand-push reel mower!).
Installing the kit is simple, but it makes you open the mower and connect
wires to its guts. This is a *good* thing though, because you get to see
how it all fits together - it's a small-scale version of what any
solar-power system is - battery, load, panels, charger/regulator (in the
panels), and battery metering (built into the mower). After monkeying
with much larger systems, this really struck me as a simple, complete
teaching example of a working solar power system.
When we moved into our rental place here, the one thing we didn't like so
much (and wouldn't have on our "real" place, without a goat or to to
help) was the huge expanse of grass there was to mow. We were used to
our little suburban plot, which could easily be handled by our
human-powered reel mower. We tried valiantly with the reel mower,
until we realized it was going to take a week to get through the whole
thing, at which time we'd be starting over :( The thought of having to
buy a gas-guzzler didn't sit well with us, so we opted for this solar
solution. The advantages -
* Never need to buy gas for the mower (or pay the power company)
* Quiet operation
* Cuts faster, wider, and jams less than the reel mower (cuts like any
other "conventional" mower)
* Teaches you all the basics of living with a photovoltaic system that
does something practical
The things you do here that are just smaller-scale versions of what you'd
do on a whole-house system -
* wiring together solar panels using their built-in junction boxes
* connecting a solar charger to a lead-acid battery bank
* gauging battery charge and power use
* mounting solar panels - I used 2' lengths of pre-drilled, galvanized
angle-iron from the local hardware store ("project iron", some people
call it) and #10 galvanized hex-head bolts and matching nuts. The bolt
heads slide into grooves on the back of the panels.
* orienting mounted panels to receive optimum sun
* being amazed that it all just works, and you don't have to do much of
anything :)
(ObDisclaimer - I don't work for Real Goods, Ryobi, etc. Or, I should
add, for the people who make project iron, though I probably should,
because that stuff's *expensive* and I use it for everything :) )
Cheers,
Andy Evans Homestead Mailing List Administrator
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White Sulphur Springs, WV USA E:3 G:3 N:2.5 L:1
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