Author Topic: how to connect cells (Read 2720 times)

danerd · « **on:** February 16, 2007, 03:41:52 AM »

hello , i´m new here and my english is not the best.so i´m sorry if my language is not very good.well i just received 60 cells , 50 * 100 mm. 0,58 V and 1,30 A each. are they good,if yes how many panels can i make from these 60 cells .can anyone provide a clear plan or a picture.i tried to find that here on the board but nothing.please help me

willib · « **Reply #1 on:** February 15, 2007, 09:53:27 PM »

What voltage battery are you planning to use?

12V, 24V ?

if it is 12V , i think that they usually go for 17 Volts charging.

17V / .58V = 29.3 cells

say 30 cells per panel .

you have 60 cells = two panels.

ghurd · « **Reply #2 on:** February 15, 2007, 10:14:01 PM »

Nearly all panels use 36 cells for a 12 volt system.

danerd · « **Reply #3 on:** February 15, 2007, 10:15:19 PM »

thanks willib for the quick answer , what would be better ,a 12 volts battery or 24 volts?and why do i need 17 volts charging when the battery is 12 volts.where do difference ( 5 volts ) go .i´m sorry i think these questions seems very silly for you.

which connection schould i use a series connection or a parallel.and how , do any have a guidance for doing that .60 moduls were not cheap.so i don´t do something wrong.i appreciate your help

willib · « **Reply #4 on:** February 15, 2007, 10:25:11 PM »

This is the guy you need to talk to .

i guess i was wrong about the 17 volts .

"ghurd" works with this stuff all day

danerd · « **Reply #5 on:** February 15, 2007, 10:44:06 PM »

i hope ghurd will have the time to help me a little bit.i really want to get that damn thing working.i don´t like it when a project don´t work.i guess you all understand that .

willib · « **Reply #6 on:** February 15, 2007, 11:52:57 PM »

Is the voltage , a measured voltage?

it is hard to explain ,but the extra voltage is needed to "push" the current into the battery.

AbyssUnderground · « **Reply #7 on:** February 16, 2007, 12:40:32 AM »

Its also needed for lower light levels. The voltage will drop slightly when light does so that little bit more keeps the current flowing.

Gordy · « **Reply #8 on:** February 16, 2007, 12:50:32 AM »

Danerd,

To the question of "12 or 24 volt, which is better?"

You can get by with smaller (cheaper) wire, with the 24v as compared to 12v. For the same wattage used.

You will need to figure out what kind of equipment you want to run, and what's avalable for those voltages. Also do you want to run everything low voltage (12-24v) or use an inverter to convert the low volts up to 120 v or 220 v.

There are options and opinions out there, you will need to study up on this and decide what's best for what you want to do. Your off to a good start by asking questions here.

Gordy

danerd · « **Reply #9 on:** February 16, 2007, 01:19:06 AM »

i want to use an inverter to turn it to 230.

i have an idea,here are many guys who really haveb experience in these things,why don´t create a "how to " for solar energy showing step by step how to build a homemade panel.

i found one.the guy did a good job , but he didn´t show many steps ,like connecting the cells together ,and other vital details .why don´t you do that .

here is the link to the one mentioned above.

danerd · « **Reply #10 on:** February 16, 2007, 01:20:32 AM »

sorry i forgot to paste it

http://pyronet.50megs.com/RePower/Homemade%20Solar%20Panels.htm

http://pyronet.50megs.com/RePower/Homemade%20Solar%20Panels2.htm

ghurd · « **Reply #11 on:** February 16, 2007, 06:54:05 AM »

Some GE and BP panels use 40 cells for a 12V panel.

The 0,58V is 'Open Circuit' with no current flowing.

In operation the voltage per cell will be closer to 0,48.

They panel needs to operate at 17V because of voltage losses.

If current flows, voltage is lost.

Wires, connections, diodes or controller will all cause losses.

A 12V battery is Dead at 11,9V, and Full at 12,6V.

However, it needs charged to 13,7 ~ 14,4V to become Full efficiently.

Cold battery temperatures need higher voltages.

Some panels were made with 32 or 33 cells. They were called "self regulating".

They could not make enough voltage to over charge the battery, but they often could not make enough voltage to overcome the voltage losses, and still have enough voltage to charge a battery.

I do not believe any company makes them now.

I would recommend building 1 panel with 40 cells,

unless you can get 20 or 30 more cells to build 2 panels with 36 cells each.

Some cells will break.

I would recommend a 12V system.

One panel will be about 20 watts at 12V using the standard rating method.

Wire losses will not be large with 'normal' size wire.

One battery. Cheaper and more common inverters, lights, etc.

Instructions on how to build a panel will be different, because everyone has different materials, skills, and ideas.

Read how other people made them, think about what you can do,

pay attention to problems they had after the panel was built.

Search page after page in the 'solar' link at the top.

There is a lot of information here.

When you find something you like, click the users name and look at his other stories and diaries for more information.

Avoid buying booklets.

Where are you?

G-

wooferhound · « **Reply #12 on:** February 16, 2007, 08:32:45 AM »

The hard part is not about putting the panel together, The hard part is making the panel weatherproof

danerd · « **Reply #13 on:** February 16, 2007, 09:06:06 AM »

i´m in germany ,yes ican get more cells, i just called for 12 other cells.i will do it like you said and build two panels with 36 cells each.you´ve provided very good informaions, i couldn´t get elsewhere .i also taught it would not be good to buy a book,because , you never get all informations you need.when you say it will be a 20 watts panel.do you mean it will provide 20 watts /hour at maximum .or 20 watts/day ?

danerd · « **Reply #14 on:** February 16, 2007, 09:11:36 AM »

hello wooferhound, thanks for joining the discussion, well i have already thaught about that problem,and i think i got a good solution.the bigest problem i have now , is that i don´t have a scheme for joining the cells together.i mean wich connection i should use,series or parallel .it would be very helpful if i had a picture a plan .thanks

i´ve heared some panels are filled with helium, is that true ?

ghurd · « **Reply #15 on:** February 16, 2007, 10:06:08 AM »

"Some WILL break".

This is more guidelines than a guarantee.

It should be close.

The 20W is 'rated peak power'. 17,3V x 1,15A = ~20W.

Power into the battery will be about 12,6V x 1,15 = 14.5W.

The solar insolation of your area, guessing 5 hours per day, means 1,15A x 5 hours.

The output will be 5,75 amp - hours per day. Average.

It can also be called 72 watt - hours per day. (1,15A x 12,6V x 5 hours = 72WH)

I expect to be able to use 80% of this power. Some is lost in batteries, etc.

And 72WH x 80% = 58WH, meaning a 58W load can run 1 hour per day, average.

Or a 29W load for 2 hours (29W x 2H = 58WH),

or a 116W load for 0,5 hours (116W x 0,5H = 58WH)

Wooferhound is correct. Weatherproofing the panel will be difficult.

Commercial panels are solid. Some people have built panels at window factories that had an inert gas inside, but I think it leaked out near the wires and had condensation problems.

Can you look at an old style VW solar panel? Most large panels are made about the same way.

Old style VW panel, too close-up...

http://www.otherpower.com/images/scimages/2050/VWPVCntrlr.jpg

Gordy · « **Reply #16 on:** February 16, 2007, 10:53:22 AM »

Danerd,

I haven't been there in awhile, but http://www.homepower.com/magazine/ Had a good achive of info. you might find helpfull.

Gordy

Ungrounded Lightning Rod · « **Reply #17 on:** February 16, 2007, 02:16:04 PM »

Its also needed for lower light levels. The voltage will drop slightly when light does so that little bit more keeps the current flowing.

No, it doesn't - until the light is so nearly gone that the current is about to stop entirely. Light level controls available current. The semiconductor bandgap controls generated voltage (when you've got enough light to stay ahead of spontaneous electron-hole recombination, which doesn't take much). The output voltage is the generated voltage minus resistive voltage drop (and minus the drop from draining all the freed electron-hole pairs if your current approaches the generation limit). Much of that resistive drop is in the cell coating, so there's a limit to how much you can fix it by using thicker wire from the panel to the battery.

But higher temperatures reduce the bandgap voltage, so you need extra cells to compensate. Otherwise, when you've got lots of sun and could be charging at high current, the panel's heating up makes the voltage peter out enough that you don't have the extra margin to push the available current through the wiring resistance.

(Good air circulation for cooling helps, too.)

You also need an extra cell or two to make up for the drop in the blocking diode you need to avoid discharging the battery at night through the panel leakage.

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