DIY Solar panels

[j]

Having previously had no interest in PV solar, I am now somewhat
intrigued.

I've noticed a huge number of tabbed and untabbed cells. Some that are
advertized as almost whole for prices under $.50/W. Some that are grade
A whole for ~$.70/W.

I am not sure what you do with these. Does it need glazing over it?

I've got a couple of potential uses. One is that I know of a few people
living off grid, who struggle with simple things like getting cell
phones charged. Or recharging AA and AAA batteries. Voltage input
tolerance for 12V source chargers is wide.

The other is that I have a location here where I was going to set up
domestic hot water, I have about 120SF of such. Solar could run the
pumps, although low power DC pumps are pricey.

But it seems a bit crazy, but it is little money crazy. Throwing a
couple hundred bucks at crazy is not the same as throwing a couple thousand.

Thoughts?

Jeff

 

[Winston]

Having previously had no interest in PV solar, I am now somewhat intrigued.

I've noticed a huge number of tabbed and untabbed cells. Some that are advertized as almost whole for prices under
$.50/W. Some that are grade A whole for ~$.70/W.

I am not sure what you do with these.

Leave them on the shelf until prices become less insane.

I've got a couple of potential uses. One is that I know of a few people living off grid, who struggle with simple things
like getting cell phones charged. Or recharging AA and AAA batteries. Voltage input tolerance for 12V source chargers is
wide.

The other is that I have a location here where I was going to set up domestic hot water, I have about 120SF of such.
Solar could run the pumps, although low power DC pumps are pricey.

But it seems a bit crazy, but it is little money crazy. Throwing a couple hundred bucks at crazy is not the same as
throwing a couple thousand.

Thoughts?

You are headed in the right direction.

Advise do the arithmetic and base your decision on the
total situation, sans any regard to the romance of alternative
energy. PV is still about 10x too expensive for those
of us who enjoy grid power *for most applications*.

I have three little 10W PV panels on the house right now.
They power fans that exhaust hot air out of the attic
and garage. I have about $750 in them, so they were an
extravagance. However, they have made a night-and-day
difference in my comfort and will extend the useful life
of my hideously expensive roof by several years.
I also like the fact that they will continue to work
during a summer power blackout.

The low hanging 'solar fruit' is space heating and
domestic hot water. Payback for those systems is much
quicker than that of PV, which will not 'pay back' at
all, for most folks.

--Winston

 

[danny burstein]

The other is that I have a location here where I was going to set up domestic hot water, I have about 120SF of such.
Solar could run the pumps, although low power DC pumps are pricey.

That's where a trip to your local auto junkyard comes in handy.

Plenty of 12 VDC (and you might even find one of the 24 V ones
used on some trucks) water pumps around. Cheap enough to
replace them every couple of years...

 

[Jim Wilkins]

Having previously had no interest in PV solar, I am now somewhat
intrigued.
But it seems a bit crazy, but it is little money crazy. Throwing a couple
hundred bucks at crazy is not the same as throwing a couple thousand.
Thoughts?
Jeff

I set up a Harbor Freight solar kit and a batch-type solar water heater to
experiment.
http://www.harborfreight.com/45-watt-solar-panel-kit-90599.html

The water heater is a tank at ground level with no external plumbing, fill
it with a hose through a backflow preventer and carry hot water to the
washing machine in a bucket. In addition to being much cheaper to build this
way it causes no damage when it leaks and it can't contaminate the household
water supply.

Both are at best only marginally worth the cost and effort. The water heater
saved about 5-7 cents of electricity per laundry load, the difference
between meter readings before and after. It is nice to have free hot water
in the garden hose to wash sap and bird crap off the car. The solar panels
produced only enough power to run this laptop during a week-long power
outage. I still needed a generator to run the washing machine.

I seriously doubt that the electricity saved would ever make up for wear on
the 12V batteries or the gasoline to hunt down cheap second-hand ones, even
if the solar panels were free. A 105A-H 12V battery that cost $80 holds less
than $0.20 worth of grid electricity. That's over 400 full discharge cycles
to break even.

The controller in my HF kit cuts out at 14.2V, a reasonable setting to fully
charge a battery without damage if you don't leave it connected too long.
You could use it to maintain the batteries on unused equipment over the
winter.

For experimenters the controller needs a charging current meter to aim the
panels and show you the output.
http://www.futurlec.com/Panel_Meters.shtml
http://www.adafruit.com/products/574

jsw

 

[v8z]

I set up a Harbor Freight solar kit and a batch-type solar water heater to
experiment.
http://www.harborfreight.com/45-watt-solar-panel-kit-90599.html

The water heater is a tank at ground level with no external plumbing, fill
it with a hose through a backflow preventer and carry hot water to the
washing machine in a bucket. In addition to being much cheaper to build
this way it causes no damage when it leaks and it can't contaminate the
household water supply.

Both are at best only marginally worth the cost and effort. The water
heater saved about 5-7 cents of electricity per laundry load, the
difference between meter readings before and after. It is nice to have
free hot water in the garden hose to wash sap and bird crap off the car.
The solar panels produced only enough power to run this laptop during a
week-long power outage. I still needed a generator to run the washing
machine.

I seriously doubt that the electricity saved would ever make up for wear
on the 12V batteries or the gasoline to hunt down cheap second-hand ones,
even if the solar panels were free. A 105A-H 12V battery that cost $80
holds less than $0.20 worth of grid electricity. That's over 400 full
discharge cycles to break even.

The controller in my HF kit cuts out at 14.2V, a reasonable setting to
fully charge a battery without damage if you don't leave it connected too
long. You could use it to maintain the batteries on unused equipment over
the winter.

For experimenters the controller needs a charging current meter to aim the
panels and show you the output.
http://www.futurlec.com/Panel_Meters.shtml
http://www.adafruit.com/products/574

jsw

As mentioned elsewhere in this thread, solar thermal is one of most cost
effective means of using the sun. Rather that using inefficient PV to power
a heater, using collectors that directly heat the fluid, whether its water
if you live in a mild climate, or anti-freeze run through a heat exchanger
to heat water. A small PV 30-40watts can run an effeicient circulation
pump, and there are numerous designs for differential controllers out on the
web, of available pre-manufactured like the Eagle products, to control when
the pumps runs relative to temps in the system.

 

[Curbie]

This on-line book goes into the fine detail of building PV panels:
"Build Your Own Solar Panel" $12.95
by Phillip J. Hurley
http://www.goodideacreative.com/solarpanel.html
Table of contents:
http://www.goodideacreative.com/spcontents.html

Although, I like the encapsulated method of moisture sealing PV panels
better as shown here:

Curbie

 

[Jim Wilkins]

Simpler than the digital ammeters that require power - an analog meter
that is inserted in the line from the solar panels:
http://www.ebay.com/itm/DC-10A-AMP-...619?pt=LH_DefaultDomain_0&hash=item3a70809ae3

And it's $5.45US includng shipping.

Is it 1% accuracy? Unlikely, but in this qpplication absolute
accuracy isn't important - you're just looking for the maximum
reading as you adjust the position of the solar panel(s).

John

Actually I get used meters cheap from ham radio flea markets amd surplus
stores, but I can't suggest that here.

The HF controller has a power switch for its LED voltage display. If you are
seriously trying to minimize electric use or are without it you can read the
LED display without turning on the room lights.

jsw

 

[j]

This on-line book goes into the fine detail of building PV panels:
"Build Your Own Solar Panel" $12.95
by Phillip J. Hurley
http://www.goodideacreative.com/solarpanel.html
Table of contents:
http://www.goodideacreative.com/spcontents.html

Although, I like the encapsulated method of moisture sealing PV panels
better as shown here:

Thanks.

It appears to me that by the time you buy the frames, tempered solar
glass and sealant that you have spent a $1/W or so before you've
purchased the cells.

Do I have that right?

Cheers,
Jeff

 

[j]

I set up a Harbor Freight solar kit and a batch-type solar water heater to
experiment.
http://www.harborfreight.com/45-watt-solar-panel-kit-90599.html

The water heater is a tank at ground level with no external plumbing, fill
it with a hose through a backflow preventer and carry hot water to the
washing machine in a bucket. In addition to being much cheaper to build this
way it causes no damage when it leaks and it can't contaminate the household
water supply.

I've got 6 unglazed panels I made a few years back. Each panel has a 1"
manifold on top and bottom, feeding 1/2" copper risers. The collector
plate is aluminum flashing and is effectively 3 layers. A huge number of
rivets and time involved in bending the plates to form around the riser.
Each panel is 2' x 10' or so (120 SF total). I ran put out of time and
money before I glazed them! And I made the boxes out of MDF which is a
huge mistake.

If I were to do this again, I'd probably save all the cost of copper and
aluminum and do a Thomason style trickle down collector with mylar and
SunTuf. Or perhaps a batch heater like yours and save a lot of money and
time! Not to mention having it up and running!

On my south facing wall, I have 200 SF of Kreamer style pass through air
collector feeding into the existing ventilation ducts.

Both are at best only marginally worth the cost and effort. The water heater
saved about 5-7 cents of electricity per laundry load, the difference
between meter readings before and after. It is nice to have free hot water
in the garden hose to wash sap and bird crap off the car. The solar panels
produced only enough power to run this laptop during a week-long power
outage. I still needed a generator to run the washing machine.

I seriously doubt that the electricity saved would ever make up for wear on
the 12V batteries or the gasoline to hunt down cheap second-hand ones, even
if the solar panels were free. A 105A-H 12V battery that cost $80 holds less
than $0.20 worth of grid electricity. That's over 400 full discharge cycles
to break even.

Yeah, I think you either need to be off grid or grid tied to make sense
of PV. But electricity is getting pricier and PV cheaper.

 

[Jim Wilkins]

... If I were to do this again, I'd probably save all the cost of copper
and aluminum and do a Thomason style trickle down collector with mylar and
SunTuf. Or perhaps a batch heater like yours and save a lot of money and
time! Not to mention having it up and running!
...
Jeff

The self-contained batch heater requires yard space with good sun exposure
and perhaps more attention to its appearance. I painted mine to match the
foundation and house. It looks like a doghouse when it's closed, not a
wierdo science experiment (got those too). Recovery time for the 40 gallon
tank is a day or two, so it's better for laundry than showers.

jsw

 

[Curbie]

I think on a small scale, you'd be lucky to produce the panels
including cells but excluding a lot fussy labor for same cost as
buying commercial panels, so not unless you doing something special,
like collecting solar for both PV and thermal from the same limited
panel area, if cost is your primary driver, I don't think you'll beat
buying commercial PV panels.

If you are doing both solar PV and thermal, combining the two help the
efficiency for PV in the summer when you probably don't need the heat
collect from the thermal, but the efficiency for thermal when you need
heat in the winter is going to be far less than a dedicated thermal
panel.

How many hours of full sun energy do you get in coldest month?

Curbie

 

[Winston]

The self-contained batch heater requires yard space with good sun exposure
and perhaps more attention to its appearance. I painted mine to match the
foundation and house. It looks like a doghouse when it's closed, not a
wierdo science experiment (got those too). Recovery time for the 40 gallon
tank is a day or two, so it's better for laundry than showers.

That is high tech, Jim!

Right now, I'm experimenting with solar reflectors.

I have some surplus acrylic mirror material taped to some MDF
which is propped up on a step ladder. It reflects solar
energy from the back yard into the kitchen/living room area.
It brightens the place up a lot. The stuff is $7 to $10 a
square foot, so I buy cheap 'drops' of it when I'm in the
area of my plastic monger.

Curiously, aluminum foil did not reflect nearly as well as I'd
hoped. The crinkly surface puts too much power at inconvenient
angles. Also, I find that plain (non-mirror) acrylic appears
to work nearly as well as does the expensive 'mirror' stuff
in reflecting sunlight.

I've also discovered that merely opening a screen door and
allowing my garage exhaust fan to pull in heated air from outside
heats the place up a *lot* faster than does my solar reflector.

--Winston

 

[Vaughn]

The water heater is a tank at ground level with no external plumbing, fill
it with a hose through a backflow preventer and carry hot water to the
washing machine in a bucket. In addition to being much cheaper to build this
way it causes no damage when it leaks and it can't contaminate the household
water supply.

I remember when square bathtub-type solar hot water heaters were common
on roofs of older homes in the south Florida area. They were little
more than a black tar-coated tank of water on the roof. I assume they
were unpressurized. They likely had a toilet-style ballcock to keep them
full, and served the house through gravity feed.

There was no separate solar collector, the tank itself serves as the
"collector". Inefficient, but cheap and reliable.

As for the naked PV cells that the OP asked about, In a world where a
careful buyer can purchase panels for 1 dollar/watt, I would need to buy
them at far less than 50 cents/watt to bother with them. The best
homebuilt panel is probably inferior to the crappiest factory built unit.

Vaughn

 

[j]

I think on a small scale, you'd be lucky to produce the panels
including cells but excluding a lot fussy labor for same cost as
buying commercial panels, so not unless you doing something special,
like collecting solar for both PV and thermal from the same limited
panel area, if cost is your primary driver, I don't think you'll beat
buying commercial PV panels.

That is what I've come to think too. The cost of the incidentals is too
high.

If you are doing both solar PV and thermal, combining the two help the
efficiency for PV in the summer when you probably don't need the heat
collect from the thermal, but the efficiency for thermal when you need
heat in the winter is going to be far less than a dedicated thermal
panel.

How many hours of full sun energy do you get in coldest month?

Here is the NREL insolation calculator:

http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/

I'm in Atlanta, Ga. Completely overcast and drizzly today. The collector
is at or slightly above inside ambient and has been off all day. But
then it is 59F outside!

My "butler" is in the Solar Cabana reading. That is at 64. On a clear
cold day that can easily get into the 80's and up and temps in direct
sun over 100. When the sun goes down though, the temperature plummets.

Usually the coldest days are the clearest.

What I would like to do is put the solar hot water online and do staple
up underfloor radiant with the stored hot water. That way I could be
nearly all solar heated. Next year, I think...

Jeff

 

[j]

Right now, I'm experimenting with solar reflectors.

I have some surplus acrylic mirror material taped to some MDF
which is propped up on a step ladder. It reflects solar
energy from the back yard into the kitchen/living room area.
It brightens the place up a lot. The stuff is $7 to $10 a
square foot, so I buy cheap 'drops' of it when I'm in the
area of my plastic monger.

Curiously, aluminum foil did not reflect nearly as well as I'd
hoped. The crinkly surface puts too much power at inconvenient
angles. Also, I find that plain (non-mirror) acrylic appears
to work nearly as well as does the expensive 'mirror' stuff
in reflecting sunlight.

FWIW, I ran across this, again, today:

http://wims.unice.fr/xiao/solar/diy-en.pdf

Since you have the mirror source. Although you can get metalized mylar
cheap.

I had thought of doing an acoustic stirling (or a simple variation), but
the amount of dead clear days is too few here, and the complexity, too much.

There is a lot to be said for simple ideas that work! Like your
reflector and fan!

Jeff

 

[Jim Wilkins]

That is high tech, Jim!

Whatever is appropriate. I can be VERY high-tech if someone else pays for
it.

Right now, I'm experimenting with solar reflectors.
I have some surplus acrylic mirror material taped to some MDF
which is propped up on a step ladder. It reflects solar
energy from the back yard into the kitchen/living room area.
...
Curiously, aluminum foil did not reflect nearly as well as I'd
hoped. The crinkly surface puts too much power at inconvenient
angles. Also, I find that plain (non-mirror) acrylic appears
to work nearly as well as does the expensive 'mirror' stuff
in reflecting sunlight.

http://en.wikipedia.org/wiki/Total_internal_reflection

I've had an acrylic mirror outdoors exposed to rain (but not sun) for about
ten years, and it's still in good condition. It was a truck mirror repair
kit from WalMart.

jsw

 

[Jim Wilkins]

...> I'm in Atlanta, Ga. Completely overcast and drizzly today. The
collector is at or slightly above inside ambient and has been off all day.
But then it is 59F outside!...
Jeff

My father is from the Atlanta area. One year my parents went down to visit
in the winter. A below-freezing cold spell struck and no one's heat pump
could keep up. The folks came back to Concord NH to warm up.

 

[j]

My father is from the Atlanta area. One year my parents went down to visit
in the winter. A below-freezing cold spell struck and no one's heat pump
could keep up. The folks came back to Concord NH to warm up.

:-O

A few years back we had a snowstorm predicted. All the schools and most
businesses closed. No storm that day, but they were sure it was just
delayed. So the schools and businesses stayed closed.

Three days of closings, and it never snowed.

We don't do winter weather well. You should see them drive in it, ...
from a distance!

Jeff

 

[Jim Wilkins]

We don't do winter weather well. You should see them drive in it, ... from
a distance!

Jeff

That happens as far north as Pennsylvania. For New York and above a little
snow is a minor nuisance. We don't take well to the 100F heat with high
humidity when we are downwind of you, though. Luckily it's rare in NH, and
alternates with beautiful cool dry air from Canada. Canadian weather is less
welcome in winter.

My brother tells me the GA and SC highway departments have at least learned
to recognize pictures of snowplow trucks.

Watch the winter temps in Atlanta and Anchorage. Some years they aren't far
apart.

jsw

 

[Winston]

j wrote:

(...)

http://wims.unice.fr/xiao/solar/diy-en.pdf

Wow! Lots of detail in that report. Thanks!

Since you have the mirror source. Although you can get metalized mylar cheap.

If I were to make that sort of collector, I'd consider a sheet
of aluminum Coilzak lighting sheet. It has the specular surface
already and would form a parabola easily.

I had thought of doing an acoustic stirling (or a simple variation), but the amount of dead clear days is too few here,
and the complexity, too much.

There is a lot to be said for simple ideas that work! Like your reflector and fan!

So far, the reflector has not moved much heat. The experiment was a success,
but the technique falls far short of adequate performance.

I suspect that these Heat Grabbers would work much better:
<http://www.motherearthnews.com/Do-It-Yourself/1977-09-01/Mothers-Heat-Grabber.aspx>
<http://www.motherearthnews.com/Natu...Mothers-Fluorescent-Tube-Solar-Collector.aspx>

--Winston