I currently have 2 x 80 watt solar panels. House batteries 2 x 6 volt connected in series and 1 x 12 volt, all 100 amp batteries. I've noticed on days of continuous rain and heavy overcast the voltage output can get down to 11.8 volts. That's the setting my refrig. will cut off due to low voltage. So today I'm fitting another solar panel, it's 75 watts, giving me at total of 235 watts. The PV Controller is rated at 20 amps, so I wont change it for a 30 amp, which was my original intention.
Having several batteries doesn't solve the low voltage problem unless you have the ability to recharge. That means extra solar panels. Hopefully now my problem will be solved.
It's only happened a couple of times and to solve the problem at the time, I fired up the engine and let the alternator charge the house batteries for about 30 minutes.
I'm making this post as it may help others who have or may have a similar problem.
GaryKelly said
05:28 PM Jan 20, 2014
One aspect I find interesting is the solar panel mismatch. I currently have one panel that came with the camper. I was told it was a 70 watt. So far it seems okay charging one 105ah battery. The fridge runs on gas so I only use the battery for the laptop, occasional TV and a few other bits and pieces. But there may come a day when I upgrade the panel and install a second battery. I take it I can add another panel - say a 120 watt and keep the 70 watt? In other words, my question is does it matter if two or more panels are not the same wattage? Move over, BG, I'm stealing your thread.
KFT said
05:59 PM Jan 20, 2014
you bluddy are too GK- hijacker.
never mind it happens quite a bit around here as you might have noticed
this forum is pretty easy going with most things.
I cannot see a problem with what BG is doing or what you want to do provided!
1. the panels are ALL 12 volt rated
2. they are connected to a regulator that will handle the sum of the currents
3. best id they are of the same construction eg, monocrystalline.
4. the batteries must be the same chemistry eg AGM and preferably the same size. same age would be good but not critical from experience.
someone else will have another opinion so wait a while and see what you get served up then you choose.
frank
brian said
08:17 PM Jan 20, 2014
Frank is on the money.
Provided panels in parallel are the same voltage, they can vary greatly in capacity, they can also be of different crystalline structure.
Even putting amorphous in parallel with mono panels will work fine.
If in series then they must be the same capacity.
KFT said
08:25 PM Jan 20, 2014
brian wrote:
Frank is on the money.
they can also be of different crystalline structure.
Hey thanks Brian, I was not certain of that parameter so stayed in safe mode.
appreciate you clearing that up for me
frank
Big Gorilla said
07:14 AM Jan 21, 2014
Even though I have an electrical background, I don't profess to be a wiz on 12 volt or any low voltage stuff, especially solar, I always left that to an Auto Electrician. Since acquiring a MH I have studied solar and low voltage, and admittedly, still learning.
What Frank is saying, I'd say is correct, same also for Brian's comments. When I get on the road next month, I'll have the opportunity to try it out. If I find any problems, I'll report them here on this Forum.
dazz49 said
09:45 PM Jan 21, 2014
Hi there. I agree that the panels can be different voltages. What i think does need to be similar though is the Maximum output voltage of the panels. Most are around 17.6 volt to 18 volt, yet some panels are only rated to 14 volt. I would not be pairing a 14 volt max op with an 18 volt op. daz
I currently have 2 x 80 watt solar panels. House batteries 2 x 6 volt connected in series and 1 x 12 volt, all 100 amp batteries. I've noticed on days of continuous rain and heavy overcast the voltage output can get down to 11.8 volts. That's the setting my refrig. will cut off due to low voltage. So today I'm fitting another solar panel, it's 75 watts, giving me at total of 235 watts. The PV Controller is rated at 20 amps, so I wont change it for a 30 amp, which was my original intention.
Having several batteries doesn't solve the low voltage problem unless you have the ability to recharge. That means extra solar panels. Hopefully now my problem will be solved.
It's only happened a couple of times and to solve the problem at the time, I fired up the engine and let the alternator charge the house batteries for about 30 minutes.
I'm making this post as it may help others who have or may have a similar problem.
never mind it happens quite a bit around here as you might have noticed
this forum is pretty easy going with most things.
I cannot see a problem with what BG is doing or what you want to do provided!
1. the panels are ALL 12 volt rated
2. they are connected to a regulator that will handle the sum of the currents
3. best id they are of the same construction eg, monocrystalline.
4. the batteries must be the same chemistry eg AGM and preferably the same size. same age would be good but not critical from experience.
someone else will have another opinion so wait a while and see what you get served up then you choose.
frank
Frank is on the money.
Provided panels in parallel are the same voltage, they can vary greatly in capacity, they can also be of different crystalline structure.
Even putting amorphous in parallel with mono panels will work fine.
If in series then they must be the same capacity.
Hey thanks Brian, I was not certain of that parameter so stayed in safe mode.
appreciate you clearing that up for me
frank
Even though I have an electrical background, I don't profess to be a wiz on 12 volt or any low voltage stuff, especially solar, I always left that to an Auto Electrician. Since acquiring a MH I have studied solar and low voltage, and admittedly, still learning.
What Frank is saying, I'd say is correct, same also for Brian's comments. When I get on the road next month, I'll have the opportunity to try it out. If I find any problems, I'll report them here on this Forum.
Hi there.
I agree that the panels can be different voltages. What i think does need to be similar though is the Maximum output voltage of the panels. Most are around 17.6 volt to 18 volt, yet some panels are only rated to 14 volt. I would not be pairing a 14 volt max op with an 18 volt op.
daz