Solar array amperage drop help please???

[rootytootie]

I had my solar panel set up for a couple months now and just started to monitor the power output. Right now I have a 90 watt harbor freight kit, and 2 80 watt mono and 2 80 watt poly panels. All are wired in parallel so it should add to about 410 watts at around 20 volts right? I know voltage drop for battery bank after charge controller. So it converts it down to 13 volts. I have an amp meter wired in series before the charge controller and at peek time I only see it reach 14 amp. 14 x 13 volts is 182 watts I am only getting out of the panels. So I cam losing almost 60% of my potential power output from the panels!!!! Why is that? I thought that the amps do not change only the voltage drop for the batteries, so my meter should read almost 20 amps. Which would be 20 x 13 volts = 260 watts output from panels. That is only around 40% of power loss. I am so confused and not happy with the results I am reading here with the amount of money I spent for all of this. Thanks for every ones time and help.

[hay4man]

You have three different types of panels wired in parallel. They will only generate close to their rated power if they are each operated close to their maximum power point voltage, but instead they are all forced to operate at the same voltage (because they are in parallel).

If each of the three panels has a different max power point (a different number of cells in series), then you won't get close to your full rated power.

You might need more charge controllers.

[Mike90250]

Well, it is winter where I am, and output drops in winter.

Also, some types of panels (amphourus) degrade over time, and reduce output.

[rootytootie]

I have a cheap crap charge controller. It is only a 10 amp charge controller. Could that be holding it back also? Also does that mean I have to run another set of wires in the house to another charge controller for the harbor freight system? But if I do that I can stll wire in into the same battery bank right? And the amorphous panels are only a couple months old.

[Mike90250]

amorphous panels fade 10-20% in the first 6mo, and then 5-10% yearly after that.

[hay4man]

Wait, you are measuring amperage coming out of the solar array? To get power, you also need to measure the voltage across the solar array.

I think you are multiplying array output current by battery voltage. The purpose of the charge controller is to operate at a maximum power point which is usually not the same as the battery voltage.

[rootytootie]

I think it is limiting it to 14 volts coming in. I need a better charge controller I know that. I just want to figure out how to get the most power out of these things for the money spent. Would diodes help? When I took out the amorphous panels i was reading 12 amps so 3 amps from each of the 80 watt panels. So I was still losing 1 amp from each panel. Then when I wired the amorphous panels back in it went to 14 amps, so that 90 watt set only added 2 amps, so Im losing 2 amps from that.

[hay4man]

If you have panels in parallel, you should put a diode in series with each panel.

If you put panels in parallel, you should confirm that they are all meant to operate at the same voltage (or close to the same voltage).

How much power do you get with just the amorphous cells?

You are measuring current directly into the battery, right?

Alex

[Mike90250]

If you are using a charge controller, it likely has the diode function in it. (diodes prevent a small nighttime discharge from the battery thru the panels)

AFIK, the HF kit has a worse than &#^@ controller in it. Look to something with a name behind it, like MorningStar, Trace/Xantrex charge controller.

No need to add diodes at each panel, each diode reduces your voltage output by about a volt.
Large strings of panels, when paralled, have fuses installed, but I've never heard of diodes for parallel strings.

[hay4man]

You should install blocking diodes in series with each panel, if you have connected them all in parallel, or else you're stronger panels will backfeed energy into the weaker panels. In fact...I wouldn't be surprised if this was your problem.

[hay4man]

For reference, check out the bottom graphic. The bypass diodes are built in to the modules already. But if you want to put them in parallel, you should add blocking diodes.

http://pvcdrom.pveducation.org/MODULE/Array.htm

[Jason]

For reference, check out the bottom graphic. The bypass diodes are built in to the modules already. But if you want to put them in parallel, you should add blocking diodes.
http://pvcdrom.pveducation.org/MODULE/Array.htm

great link. thank you for that

[Mike90250]

But if you want to put them in parallel, you should add blocking diodes.

Can you document this notion from any panel mfg, or charge controller manual, or anywhere ? (besides the pveducation.org site, which only recommends them if you have panel shading issues or gross mismatch panels.)

[hay4man]

Well, I suppose if you have well matched panels, and no shading problems, and the panels are pointed in the same direction, the blocking diodes aren't necessary.

Blocking diodes are mentioned in this thing (I guess it's called an isolation diode):

http://www.gpelectric.com/commonfiles/libraries/docs/manuals/GP-RV_Install_Kit_Manual.pdf

rootytootie, Before tossing the amorphous panels, test them out individually on the charge controller. One thing that would help us help you is if you provided the open circuit voltage for each of your panels.

If you are using a charge controller that's only rated for 10 amps (which somehow surprisingly puts out 14), you should probably buy another charge controller.

[P34CHY]

Hi guy's
I'm quite new to all this (first post). I hope you can help with this.
I have two kyocera 130w panels with vmp of 17.6v and imp of 7.39amp. these are wired in series for 24 system.
I also have four photon panels with vmp of 32v and imp of 3.35amp wired in parallel.

would it be safe to wire the kyocera series in parallel with the photon panels to creat
one string. if not any suggestions welcome.