What to do with extra panels????

shockman

Okay! So I have upgraded my system and feel like I have power I don't know what to do with!! :>), however soon I will be running a small freezer which I'm not worried about, and will try running an air conditioner for the really hot days.
What I have that's not being used are 6 old ARCO panels, 15.2V 55watts, and 2 newish 125W 12V panels. On the roof of my cabin there is already a supply wire that was used for solar before my ownership. I still have an old 30A PMW controller from the original system. The supply wire to control room looks like a 3conducter teck cable about 45 feet long, probably a 10 or 12 awg? The ends have been coupled together, copper grnd with 1 conducter and the other 2 conducters together?? should act as a larger wire?? So! I'm wondering what to do? use only the 2 new 12V panels or all of them and can I just send the current from the PMW to my distribution box?? will this additional current confuse my classic 150?? I'm assuming it will not be recommended to send current to the classic??
Any thoughts on how to use these extra panels would be appreciated, seems a shame to have them sitting in the shop.
I think the details of my system are in my sig.

Cariboocoot

Re: What to do with extra panels????

Working up from the bottom, so to speak ...

Attaching additional charge sources to you batteries will not confuse the Classic. Lots of people run multiple charge sources with different controllers with varying degrees of success (inability to get Voltage readings/set points to match exactly is the biggest problem).

The existing wiring I wouldn't trust for anything. It is an unknown, and probably best removed.

The two 125W panels are probably Vmp 17.5 Imp 7 and could be used in parallel on the PWM controller to add another 14 Amps if needed. You might want to orient them easterly to toss a bit more current in first thing in the morning or westerly to try and keep float going as long as possible. You have a large battery bank (760 Amp hours @ 12 Volts?) and 14 Amps won't do much but every little bit helps. Your "big" array probably manages about 63 Amps peak, so another 14 would actually put the max current in the 10% range for those batteries.

The Arco panels are a waste. Sell them. At 15.5 Volts they are too low to provide proper charging of a 12 Volt system so they'd need to be reconfigured as two in series by three parallel and run through MPPT to get the Voltage right. This would be 330 Watts and would exceed a Morningstar 15 Amp MPPT controller's ability on a 12 Volt system. Is it worth spending $$$ for a controller to get 20 Amps more? I doubt it. You could always just "waste" the extra power through a PWM controller: 3.5 Imp * 3 = 10.5 Amps, half of the panels contributing a fraction of their power just to boost the Voltage up. Not very efficient.

Maybe someone else has a better idea.

shockman

Re: What to do with extra panels????

I did wonder about useing the Arco's as they have been frowned at in the past when I was using them. I don't really understand how they would work in parallel with the new ones???? What would the end result be of mounting all of them vs just the 2 new ones?? I will put them on the roof which faces about due south and is angled about 22 deg. without creating myself a bunch of work (much easier to mount only the 2 new ones) I could only adjust the angle but not the direction.

Cariboocoot

Re: What to do with extra panels????

The main problem with the Arco panels is that their Voltage at maximum power is much lower than what the others are (typically Vmp 17.5 for a 12 Volt system) and after line losses may not produce enough Voltage to bring a 12 Volt battery up to charge levels.

In conjunction with the others the best they'd do is add a bit or current when the Voltage is lower. Most likely the higher Voltage panels will pull the Arco Voltage up above Vmp towards Voc, and in doing so the Arco's current output will fall.

redwire

Re: What to do with extra panels????

I think he is saying 15.2V max power output, most arco panels are 21V open circuit and around 16.9V max power so I don't know where 15.2V comes from.

Make a separate system for lighting or some other use, get a crappy small charge controller, grid tie them, heat your hot water heater with them, search google for other uses, but do something with them! I hate seeing any panel go to waste!

The 2 wires combined is like a larger wire, yes. With copper prices going up and up I would inspect the insulation and if it's OK, no big cracks, use it. You are not talking about high voltages.

shockman

Re: What to do with extra panels????

Attachment not found. see if this works!!!!

shockman

Re: What to do with extra panels????

WHOA!! didn't think I could do that!!!
Never know how to interpet this label as it seems to use different terms than my newer panels
I planned on useing the exsisting wire as it has the conducters wrapped in insulation and then wrapped again in metal with rubber coating?? I think called teck cable?? seems to be in good shape and has not been exposed to elements except for business end where it was on roof, can cut 5ish feet off of it and expose new section.

Cariboocoot

Re: What to do with extra panels????

Vmp 15.2 * Imp 3.37 = 51.2 Watts. The very high Voc of 24 is a bit odd (so is rating it at 0C); amorphous panels perhaps? 3.37 Amps is the Isc.

BTW, do not use wires in parallel without individual circuit protection on each wire; if one should develop a fault the other won't have to carry the full current.