Small Solar Chargers

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On Tue, 02 Aug 2005 17:29:03 +1200, Richard wrote:

Landline wrote: On the URL for the ICP it states - Online Store: Out of stock, no further stock is due. I would say the product was unsuccessful due to the miserable charging current and time taken to charge 4 x AA batteries.
I have a warehouse solar light outside here, has a single 600ma AA cell in it.
I fully charged it in my proper battery charger and got 5 and a bit days use out of the light (was charging during the day) - now its flattened out, the light runs for about 2-3 hours each night before it goes so dim its even more useless and then starts flashing.
So useless charge times doesnt mean something wont be sold ;)

I got one of the warehouse jobbies as they where so cheap. I am looking at putting in into the loo, but putting the led on a long wire.
I think the best deal I was a sola powered car charger, with overcharge protection. With 12V I could wire up some nice led clusters around the house.
Brett

no wrote:

On Tue, 02 Aug 2005 17:29:03 +1200, Richard wrote:
Landline wrote:
On the URL for the ICP it states - Online Store: Out of stock, no further stock is due. I would say the product was unsuccessful due to the miserable charging current and time taken to charge 4 x AA batteries.
I have a warehouse solar light outside here, has a single 600ma AA cell in it.
I fully charged it in my proper battery charger and got 5 and a bit days use out of the light (was charging during the day) - now its flattened out, the light runs for about 2-3 hours each night before it goes so dim its even more useless and then starts flashing.
So useless charge times doesnt mean something wont be sold ;)
I got one of the warehouse jobbies as they where so cheap. I am looking at putting in into the loo, but putting the led on a long wire.
I think the best deal I was a sola powered car charger, with overcharge protection. With 12V I could wire up some nice led clusters around the house.
Brett

It is interesting to see these solar lights "pushing the envelope" (more accurately seeing what they can get away with before the customer realises the product is so useless they won't buy any more).
I bought a solar light from TWH a couple of years ago, it had a large solar panel (~70x70mm) and two AA Nicads - and it ran for most of a night in summer. It was bloody good. Unfortunately a ladder fell on it :-(
Replacement unit has a much smaller panel (~50x50mm), one AA Nicd, runs for maybe 3 hours max in summer. It is useless.
And now I see even cheaper lights with panels the size of a postage stamp - image how useless these are going to be.

"-=rjh=-" wrote in message

no wrote: On Tue, 02 Aug 2005 17:29:03 +1200, Richard wrote:
Landline wrote:
On the URL for the ICP it states - Online Store: Out of stock, no further stock is due. I would say the product was unsuccessful due to the miserable charging current and time taken to charge 4 x AA batteries.
I have a warehouse solar light outside here, has a single 600ma AA cell in it.
I fully charged it in my proper battery charger and got 5 and a bit days use out of the light (was charging during the day) - now its flattened out, the light runs for about 2-3 hours each night before it goes so dim its even more useless and then starts flashing.
So useless charge times doesnt mean something wont be sold ;)
I got one of the warehouse jobbies as they where so cheap. I am looking at putting in into the loo, but putting the led on a long wire.
I think the best deal I was a sola powered car charger, with overcharge protection. With 12V I could wire up some nice led clusters around the house.
Brett
It is interesting to see these solar lights "pushing the envelope" (more accurately seeing what they can get away with before the customer realises the product is so useless they won't buy any more).
I bought a solar light from TWH a couple of years ago, it had a large solar panel (~70x70mm) and two AA Nicads - and it ran for most of a night in summer. It was bloody good. Unfortunately a ladder fell on it :-(
Replacement unit has a much smaller panel (~50x50mm), one AA Nicd, runs for maybe 3 hours max in summer. It is useless.
And now I see even cheaper lights with panels the size of a postage stamp - image how useless these are going to be.

Here in California, at the home improvement stores, the solar lights go for as low as $60 for 12 or around $5 a piece. I don't know how much of a cell, battery and light they can provide and still profit.

Paul wrote:

Here in California, at the home improvement stores, the solar lights go for as low as $60 for 12 or around $5 a piece. I don't know how much of a cell, battery and light they can provide and still profit.

You can get them individually from the Warehouse here for 3 or 4 dollars, last time I was down there.
Cheers, Nicholas Sherlock

"Nicholas Sherlock" wrote in message

Paul wrote: Here in California, at the home improvement stores, the solar lights go for as low as $60 for 12 or around $5 a piece. I don't know how much of a cell, battery and light they can provide and still profit.
You can get them individually from the Warehouse here for 3 or 4 dollars, last time I was down there.
Cheers, Nicholas Sherlock

That is the point. Someone on here (maybe this thread) was looking for a super low cost PV for battery charging. I would say just find out where the solar light people get theirs.

In Paul wrote:

"Nicholas Sherlock" wrote in message Paul wrote: Here in California, at the home improvement stores, the solar lights go for as low as $60 for 12 or around $5 a piece. I don't know how much of a cell, battery and light they can provide and still profit.
You can get them individually from the Warehouse here for 3 or 4 dollars, last time I was down there.
Cheers, Nicholas Sherlock
That is the point. Someone on here (maybe this thread) was looking for a super low cost PV for battery charging. I would say just find out where the solar light people get theirs.

China.
(I don't know this for a fact, but for any super low-cost product sold by the millions there's a 99% chance I'm right :o)
-- Roger Johnstone, Invercargill, New Zealand http://vintageware.orcon.net.nz/ ________________________________________________________________________ No Silicon Heaven? Preposterous! Where would all the calculators go?
Kryten, from the Red Dwarf episode "The Last Day"

Paul wrote:

Here in California, at the home improvement stores, the solar lights go for as low as $60 for 12 or around $5 a piece. I don't know how much of a cell, battery and light they can provide and still profit.

Now that its getting sunnier here its lasting till about 11pm before its dim, and about midnight before it starts flashing on and off.
Theres no mention on the box of it lasting all night so I guess they are off the hook. If I paid more then NZ$3.80ish for it I would be somewhat pissed off.

N.L.Junkie wrote:

Your original question was asking what is the simplest and least expensive way to to get in to solar. Since the responses seemed geared towards conservation of your existing power my assumption is...there must not be a simple and cheap method...

Au contraire. You might make an air heater with an inexpensive sunspace or polycarbonate "solar shingles" over a south house wall for space heating with a 1-2 year payback.
Or supply close to 100% of the hot water needs for a family of 4 all year with a simple solar pond water heater like this, with a 4'x8' polyethylene- lined tank under a greenhouse with 6'x8' of 6 mil PE or 4'x12' of 0.020" flat polycarbonate film for the south wall and 6 mil PE for the north, with whitewash or reflective Mylar under the north. The south wall might have a 6' slant height. The north might be roughly parabolic, like this:
. - . . 6'. . . | . h . . . | . ................... - | d | | | 3' | | ------------------- 4' --------------- | | | | | | | | | | | | | | | | 8' | | | | | | | | | | | | | | ---------------
10 DATA 60,1020,1160,100,2410,440 15 W=4'box width (feet) 20 D=30.45001#/12'south wall to ridge distance (feet) 30 H=SQR(6^2-D^2)'ridge height above water level (feet) 40 PRINT D,H 50 FOR CASE = 1 TO 2'January and July in Phoenix 60 READ TD,HSUN,SSUN'daytime temp (F), horiz and south sun (Btu/ft^2-day) 70 EIN=.9^3*D*HSUN'direct sun from above (Btu/wft^2-day) 80 EIN=EIN+.9^4*H*SSUN'add reflected sun (Btu/wft^2-day) 90 SUNHOURS=6*CASE'solar collection hours 100 EOUT=SUNHOURS*(140-TD)*W/2'daily heat loss from top (Btu/wft^2-day) 110 DHWHEAT=8*(EIN-EOUT)'daily hot water production (Btu) 120 DB=3'depth of box (feet) 140 QB=DB*W*8*62.33*(140-110)'heat stored on average day (Btu) 150 RB=20'R-value of db'xw'x8' box 160 AB=2*(W+8)*DB+2*W*8'box area (ft^2) 170 GB=AB/RB'box thermal conductance (Btu/h-F) 180 LB=24*(125-TD)*GB'box heat loss on cloudy day (Btu) 190 DHWL=30000'DHW load (Btu/day) 200 ND=QB/(LB+DHWL)'cloudy day storage (days) 210 PRINT CASE,DHWHEAT,LB,ND 220 NEXT
d h
2.537501 5.437011 feet
daily daily numbe of month output loss cloudy days
January 40518.5 Btu 10608 Btu 4.420568 July 40541.5 4080 5.267324
During the day, a $5 10 watt fountain pump would move tank water over a 4'x8' layer of EPDM rubber over a 2" horizontal polyiso board cover, and the water would drain back at night. Cold pressurized house water would enter a $60 1"x300' coil of PE pipe under the cover and emerge to enter the cold input of a conventional water heater inside the house, which would do nothing most of the year. The materials cost would likely be less than $300. See more details at http://builditsolar.com.
Nick

On Sun, 2 Oct 2005 00:59:54 -0700, Antipodean Bucket Farmer wrote:

Hi, Everybody,
Let's say that I want to make a small 12-volt battery supply. So I use a pair of cheap 6-volt sealed gel cells, in series.
Each of the two batteries is rated at, say, 5 Amp-Hours.
Will they add together, for a total of 10 Amp-Hours? Or will the pair just provide 5 AH at the higher voltage (I.e. 12-volts)?
Thanks...

5AH @ 12V
-- ron (off the grid in Downeast Maine)

"Solar Flare" wrote in message

Sounds like a perfect bomb target to cripple the nation easily.
"Paul" wrote in message
tkgoogle@ktcnslt.com> wrote in message steve wrote: before i picked my solar contractor, he said that IF the entire state of arizona was covered with solar panels that we could get 100% of USA's electric.
~ as an example it's pretty complelling!
Only a small fraction of AZ surface area would be needed.
ref..
http://groups.google.com/group/sci.energy/msg/a7ecfa6796c4d6e6?dmode=source&hl=en
Preliminary calcs... using 13% efficient solar panels..
~30,000 sq miles... (~80,000sq km) with ~18% of that area(~5000 sq miles) occupied by dual axis tracking solar arrays. Note: The surfaces in between and under PV trackers is still usable, maybe even desirable.
However, commercially produced solar cells are now routinely reaching 19.0% efficiency and overall panels 16.5% efficiency.
http://www.sanyo.com/aboutsanyo/press_releases_detail.cfm?id=154
Thus reducing surface area requirements by ~27% or down to 24,000 sq miles covered with ~4000 sq miles of dual axis tracking arrays..
Note: Additional PV efficiency improvements are possible.
http://www.sanyo.com/aboutsanyo/press_releases_detail.cfm?id=151 "SANYO has achieved an efficiency level of 21.6%"
===== Meanwhile =====
http://open-site.org/Regional/North_America/United_States/Arizona/
"has a surface area of 113,998 square miles,"
Plenty of room to spare with ~80% of surface remaining untouched.
The latest buzz phrase I have heard going around the last few years is: "a 100 mile by 100 mile area of solar would provide all the energy the nation needs" I am not saying I believe this, but when someone says it, it sounds impressive.

Unfortunately, we still have to work out storage and load-leveling. The US used about 12.5 exaJoules of electricity in 2002, and a total of 37.1 exaJoules. But that doesn't reflect the variations in power demand. http://eed.llnl.gov/flow/02flow.php
Daily fluctuations can approach a range of 2:1, and the peak load occurs from 3 to five hours *after* local noon. http://currentenergy.lbl.gov/ca/index.php (manually select a summertime week-day to see archives)
daestrom

wrote:

SEER rating == BTU/hr divided by Watt/hr consumed.

Just watts.

Each kWh of electricity consumed equates to 3412 BTU/Hr of thermal energy.

Just Btus.
I suggest you learn the difference between power and energy.
Nick

"Robert Morein" wrote in message

"Roy Ingham" wrote in message Thanks to all [snip] Increased the size of AC (the AC used to run very close to 24 hrs each day, probably cut off 1 am - 4am, We have increased the size, which gave some relief in term of KwH consumed each month, cleaning the filter gave us much more. We even run the AC at 80, just to quit it from running. Now it only cycles on for 10 min in every hour and cuts off at 12 pm until 6 am
Even had Florida Power come out and do a circuit test to see where the cosumption is going, they told us, they couldn't find a fault, they even replaced the meter in case it was faulty.
But being a non-profit business run from home, the door opens and closes 20 times an hour, and yes this is our big problem.
The big eater in practically any situation is A/C.

This is certainly true. Especially in a humid climate such as FL.

It dwarfs any other source of electrical consumption in a house, probably by a factor of five, even though you have it running only 10 minutes per hour. Our four ton unit draws 6888 watts. At your duty cycle, that's 27.6 kwH per day! You could read by candles and wash your clothes in a stream, but as long as you have that A/C going, you're stuck. And in Florida, where it does not get cold at night, there is little opportunity for thermal storage. From http://doityourself.com/aircond/centralaircondition.htm "In an average air conditioned home, air conditioning consumes more than 2000 kilowatt-hours of electricity per year, causing about 3,500 pounds of carbon dioxide and 31 pounds of sulfur dioxide to be emitted at the power plant and, at average electricity prices, costs you about $150. In high-cooling climates those numbers can be doubled or even higher."
So you have to solve the heat problem.
1. Stop influx of humid air: Ever see a house with a foyer, with two doors? One is the exterior door. The foyer is a small hallway that leads to a 2nd door. This cuts down drastically on influx of humid air. Build a foyer onto the outside of the house.
2. As I have just learned, one standard sol is equal to 1kw/square meter. This means that if you have a south facing window, during peak hours, that window will admit approximately 1 kw of heat energy into the building, which requires about 3.5 kw to pump out via the A/C.

Nope. You got your conversions and COP mixed up. An A/C unit uses *less* than 1kw to move 1 kw of heat input out of the house. Modern A/C units are rated at 10 SEER or better. Unfortunately, *Seasonal* Energy Efficiency Ratio doesn't translate directly to COP (Coefficient of Performance). If it did, a four ton A/C (48000 BTU/hr unit would draw just 4800 watts all the time. But the exact ratio depends on outside temp, and other things.
But generally, an A/C unit can move about 3 times the energy it consumes. So to move 1 kwh of energy out of the house, takes about 333 watt-hours (1/3 kwh), not 3 kwh.

You must prevent ingress of radiant energy through those windows. Options: deep awnings, or very expensive window technology.
3. How well is your house insulated? Is it painted white? Is the roof painted white? Brilliant white reflects the maximum amount of heat. Any other color converts some sunlight into heat that will conduct into the house.

Good ideas.

4. A refrigerator, or dehumidifier which has coils that are inside the house adds heat to the structure. Let's say you have a refrigerator that consumes 200 watts. While running, it is a heat source equivalent to a 200 watt lightbulb. The A/C consumes about 700 watts to exhaust that heat. The same goes for any other appliance you have running: TV set, radio, lightbulb, computer. So while the refrigerator is running, it is actually adding 900 watts to your electric bill!

Nope. You've made the same mistake here. A refrigerator that runs 200 watts, dumps heat into the building at 200 watts (on average over time). And that takes about 200/3 = 66 watts of power on the part of the A/C to remove it. Of course a 'fridge doesn't run constantly so these are just averages.

I believe there have been implementations of refrigerators with coils that radiate outside the house. If that is done, then the refrigerator, instead of adding 700 watts of load to the A/C, subtracts 200 watts from it.

Refridgerators are kind of interesting when you look at them with A/C. Suppose the motor draws 200 watts when it runs and it runs 15 minutes out of every hour. So in one hour's time, it has consumed 50 watt-hours of electrical energy. But, when the motor runs, the heat being dumped into the house is more than 200 watts, it also includes the heat extracted from the food inside. So it might dump heat into the house at the rate of 700 watts for those fifteen minutes. Yet, for the other 45 minutes, heat is moving from the house back into the food (that's why the unit turns on again next hour). If it runs 15 minutes out of every hour, dumping heat at 700 watts into the room when running for fifteen minutes, thats 700*0.25 = 175 watt-hours of heat into the room. When the unit is off for 45 minutes, it absorbes from the room, 166.7 watts * 0.75 = 125 watt-hours of heat.
So the *average* heat load added to the room is just the electricity consumption, not the heat energy moving in/out of the food. In my example, that's 50 watt-hours of electricity every hour. And a typical A/C unit would consume another 17 watt-hours of electricity moving those 50 watt-hours to the outside. Total electricity consumed by 'fridge and A/C is 67 watt-hours for every hour (~48 kwh/month).
Moving the coils to the outside, first we remove those 50 watt-hours of heat every hour from the A/C load. And, the heat seeping into the food is also rejected outside, so that's another ~125 watt-hours of heat every hour. So we've effectively reduced the A/C burden by 175 watt-hours every hour. If the A/C's COP is still 3.0, then we save 58 watt-hours of A/C electricity every hour (~42 kwh/month).
Putting the 'fridge coils outside isn't always easy. And with higher outside air temperatures, the 'fridge's COP will drop so that it uses more than 50 watt-hours every hour to keep the food cool.
A cheaper alternative is to have better insulation around the refridgerator and reduce the run-time from 15 minutes an hour to something like 7.5 minutes. This would be an immediate savings of 24 kwh/month. Also, check the door seals to make sure there aren't any leaks.
daestrom

daestrom wrote:

"Solar Flare" wrote in message Sounds like a perfect bomb target to cripple the nation easily.
"Paul" wrote in message
tkgoogle@ktcnslt.com> wrote in message steve wrote: before i picked my solar contractor, he said that IF the entire state of arizona was covered with solar panels that we could get 100% of USA's electric.
~ as an example it's pretty complelling!
Only a small fraction of AZ surface area would be needed.
ref..
http://groups.google.com/group/sci.energy/msg/a7ecfa6796c4d6e6?dmode=source&hl=en
Preliminary calcs... using 13% efficient solar panels..
~30,000 sq miles... (~80,000sq km) with ~18% of that area(~5000 sq miles) occupied by dual axis tracking solar arrays. Note: The surfaces in between and under PV trackers is still usable, maybe even desirable.
However, commercially produced solar cells are now routinely reaching 19.0% efficiency and overall panels 16.5% efficiency.
http://www.sanyo.com/aboutsanyo/press_releases_detail.cfm?id=154
Thus reducing surface area requirements by ~27% or down to 24,000 sq miles covered with ~4000 sq miles of dual axis tracking arrays..
Note: Additional PV efficiency improvements are possible.
http://www.sanyo.com/aboutsanyo/press_releases_detail.cfm?id=151 "SANYO has achieved an efficiency level of 21.6%"
===== Meanwhile =====
http://open-site.org/Regional/North_America/United_States/Arizona/
"has a surface area of 113,998 square miles,"
Plenty of room to spare with ~80% of surface remaining untouched.
The latest buzz phrase I have heard going around the last few years is: "a 100 mile by 100 mile area of solar would provide all the energy the nation needs" I am not saying I believe this, but when someone says it, it sounds impressive.
Unfortunately, we still have to work out storage and load-leveling. The US used about 12.5 exaJoules of electricity in 2002, and a total of 37.1 exaJoules. But that doesn't reflect the variations in power demand. http://eed.llnl.gov/flow/02flow.php

We won't be making fossil fuels from electricity.
Likewise we're not interested in replacing thermal energy sources with resistive electricity conversion. It would be a waste of resources. Solar thermal energy can be collected and stored locally at point of usage with far greater efficiency. Heat pumps could be used as a backup.
Electricity to mechanical energy conversion(94 to 96%) is by far more efficient than a typical thermal to mechanical conversion process. Reducing operational automobile energy consumption by 12x, maybe more.

Daily fluctuations can approach a range of 2:1, and the peak load occurs from 3 to five hours *after* local noon. http://currentenergy.lbl.gov/ca/index.php (manually select a summertime week-day to see archives)

Local noon is not much of an issue using dual axis trackers. Long distant HVDC lines can transport the power to where it's needed. (Previous ref'd calc's already factored in a 25% loss for cross continent HVDC transmission).
Some AI and one way comms added to appliances could solve much of storage problem. (Similar tech already used by utilities to reduce peak loads.)
I.E. Activate water heater during solar peak.. same goes for heating/cooling. Some overshoot in early/late afternoon and it should be able to coast through most of the night without turning on.
Additionally some social engineering could alter consumption patterns. (Delayed start to work day on east coast, early end of work day on west coast, etc.)
EV's surplus storage capacity could provide a significant amount of load leveling.
====
US Energy Conservation programs are poorly implemented. We have lots of wasteful products which need replacing. I.E.. Sat and Cable boxes needlessly consume ~1% of total electric supply.
====
Finally, thier are other sources of renewables. Wind, Hydro, Biomass. And non-renewables backups like Nuclear.. Coal..
Their usage would be dictated by pollution/CO2/risk contribution..

nicksanspam@ece.villanova.edu wrote:

N.L.Junkie wrote:
Your original question was asking what is the simplest and least expensive way to to get in to solar. Since the responses seemed geared towards conservation of your existing power my assumption is...there must not be a simple and cheap method...
Au contraire. You might make an air heater with an inexpensive sunspace or polycarbonate "solar shingles" over a south house wall for space heating with a 1-2 year payback.

Even so, it _is_ cheaper to conserve the power you're already using than to retrofit methods to utilize solar energy to an existing house (even with Nick's cheap solutions). otoh, if you're building a house from the ground up, it's cheap (ie, same cost as standard building practice) to build in passive solar heating -- derek