Is there a limit?

[GreenHaven]

Hi & good day to all.

My name is Ravin, and I run a non-profit organization, called Green Haven. Amongst others things, we build solar panels from scratch, for orphanages and such. Though I am relatively new at this, I have but one question for the building of my solar panels...

Is there a limit to how many cells I can use per panel, or how many panels I have per array? Like I'm wondering if I had too many cells, and the voltage exceeded 240 Volts, would that be a problem? What is the basic calculative limit I have for this?

I would really appreciate some input on this matter as it's been bugging me for quite some time. Thank you in advance for your time & kind consideration. Good day.

Ravin GH

[Mike90250]

I wish you luck. Most DIY panels fail in a year, from moisture ingress.

I'll assume these panels will be powering 12V systems. for every 12 volts, you need about 36-40 cells in series to provide enough voltage in hot conditions, to charge a battery.

[GreenHaven]

I wish you luck. Most DIY panels fail in a year, from moisture ingress.

I'll assume these panels will be powering 12V systems. for every 12 volts, you need about 36-40 cells in series to provide enough voltage in hot conditions, to charge a battery.

Hi Mike...

By moisture, you would mean the moisture collecting within the panel, between the housing, glass panel & cells yea? If so, I trust I have come up with a small solution to overcome that issue. No air pockets, no moisture...

As for what you mentioned, this is where I am confused. Yes, I will be powering a 12V system. But, I believe I will be setting up an array of at least 20-30 panels. If so, is there a "limit"? What is the calculation you used to derive at 36-40 cells? And as such, what is the amount you got?

Assuming "3.5Ampsx0.5Volts" per cell, is it a problem if I use 300 cells for my array? Will there ever be a case, where I have too much voltage or too much wattage?

Thanks for your time Mike.

Ravin GH

[Mike90250]

Several things.

1) you need about 18 - 20Volts on hand to drive a charge controller, to fully charge a 12V battery (some conditions need 15.5V for full charge, or EQ charging)

2) inexpensive PWM controllers are fine with PV voltages close to battery voltages (19V PV & 12V battery) if you increase voltage much beyond 19V, the POWER is wasted with a PWM controller, because of basic electricity behavior.

3) massively parallel arrays don't work much better, because the larger tab wire required to carry the currents, begins to shade the PV cell, reducing power.

The "professional" way to harvest power is, when designing a system, note what size wire is needed to carry the power from the array to the controller. Then you weigh the tradeoffs of the cost of copper wire for AMPS, or the cost of MPPT controllers to down-convert the 200Vs to amps, right at the batteries.

read here

http://www.solarpaneltalk.com/showthread.php?13845-Charge-Controllers-PWM-or-MPPT

and here

http://www.solarpaneltalk.com/showthread.php?7634-Watts-vs-Volt-Amps-huh

[GreenHaven]

Several things.

1) you need about 18 - 20Volts on hand to drive a charge controller, to fully charge a 12V battery (some conditions need 15.5V for full charge, or EQ charging)

2) inexpensive PWM controllers are fine with PV voltages close to battery voltages (19V PV & 12V battery) if you increase voltage much beyond 19V, the POWER is wasted with a PWM controller, because of basic electricity behavior.

3) massively parallel arrays don't work much better, because the larger tab wire required to carry the currents, begins to shade the PV cell, reducing power.

The "professional" way to harvest power is, when designing a system, note what size wire is needed to carry the power from the array to the controller. Then you weigh the tradeoffs of the cost of copper wire for AMPS, or the cost of MPPT controllers to down-convert the 200Vs to amps, right at the batteries.

read here

http://www.solarpaneltalk.com/showthread.php?13845-Charge-Controllers-PWM-or-MPPT

and here
http://www.solarpaneltalk.com/showth...-Volt-Amps-huh

Hi again Mike.

I don't want to sound silly or anything, but could you repeat that in simpler terms pls? I'm starting to think I'm not ready for the project...

Well, I understand that having a large array would not be good for accumulating power as for the current travelling in its equally massive tabbing wires. Understood, but, my array is not singular. It will be around 10 panels per home, and they are all segregated. All except one, which would have perhaps 20 panels.

I am confident to have solved the moisture, oxygen & air pocket issue, so that's why I want to proceed with this.

Back to point, "2)", I'm not sure what you said there at all. Could you perhaps advise on whether I can proceed building as many cells as I can, adding them up together etc? Is there a "limit" to how many cells I can put together, or how many panels I can put together? Is there a limit to the wattage/voltage I can produce? This is all I need to know.

Thanks again Mike.

[russ]

Ravin - I suggest you find a different way to help people. Be certain that you haven't found a new way to seal panels that no one else has thought of - you are not that smart.

[thastinger]

Is the purpose for building your own panels that you believe you can build them cheaper than you can buy them? If so, I'd look closely at your true cost.

[Mike90250]

.....
Back to point, "2)", I'm not sure what you said there at all. Could you perhaps advise on whether I can proceed building as many cells as I can, adding them up together etc? Is there a "limit" to how many cells I can put together, or how many panels I can put together? Is there a limit to the wattage/voltage I can produce? This is all I need to know.

Thanks again Mike.

"Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup”

You have to be very careful. The Dragon is electricity. The higher the voltage, the bigger the bite. There are commercial PV panels up to about 100V. Panels now carry 1,000V spec insulation, so that grid tie systems can use 600V strings of several panels.

DO NOT THINK for even a minute, that DIY panels in your garage can withstand this sort of voltage. You likely have no idea of how water vapor transmigrates through plastic and epoxy, reducing insulation and causing short circuits. I would keep DIY panel voltages under 25V per panel, and no more than 50V in a series string. When placing in parallel, use the proper fuses for each string. This might be safe in an closely supervised setting.

You are risking starting a fire with producing panels, and giving them out to people who have no idea of the hazard they will place on their thatched roofs.

[billvon]

My name is Ravin, and I run a non-profit organization, called Green Haven. Amongst others things, we build solar panels from scratch, for orphanages and such. Though I am relatively new at this, I have but one question for the building of my solar panels...

Great idea, but panels are so cheap nowadays that you are probably much better off making some money (by selling handcrafted items, rummage sales etc) and buying some of the cheap panels on the market. They will last longer and provide the orphans with much more reliable power - AND be a lot safer.

Is there a limit to how many cells I can use per panel, or how many panels I have per array? Like I'm wondering if I had too many cells, and the voltage exceeded 240 Volts, would that be a problem?

I would strongly advise not going above about 50 volts (90 cells or so in series.) Above that you start to risk shock and electrocution.

If you want to try building panels, go for it; you will learn a lot about solar power and it's a fun project to get kids to help with.

But if you are really after actual power, you would be better off getting a minimum wage job then taking the money you earn and buying panels with it. You will end up with more watts worth of panels and they will last a lot longer. (And if you are really planning on powering orphanages, you may not be doing them any favors by giving them homemade short-lived panels.)

[J.P.M.]

"Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup”

You have to be very careful. The Dragon is electricity. The higher the voltage, the bigger the bite. There are commercial PV panels up to about 100V. Panels now carry 1,000V spec insulation, so that grid tie systems can use 600V strings of several panels.

DO NOT THINK for even a minute, that DIY panels in your garage can withstand this sort of voltage. You likely have no idea of how water vapor transmigrates through plastic and epoxy, reducing insulation and causing short circuits. I would keep DIY panel voltages under 25V per panel, and no more than 50V in a series string. When placing in parallel, use the proper fuses for each string. This might be safe in an closely supervised setting.

You are risking starting a fire with producing panels, and giving them out to people who have no idea of the hazard they will place on their thatched roofs.

Dragons aside, I'd pay a WHOLE lot of attention to the above advice. Your ignorance may very well put property, and more importantly personal safety at high risk. There are safer ways to meet your goals, whatever they may be. Keep your ego out of it. You are out of your league. However well intentioned, postpone this endeavor until you educate yourself enough to appreciate the damage your current ignorance can cause to property, or personal safety, or worse.