Using low voltage disconnects on each solar panel to isolate shaded panels

[Mawrazen]

IMG_6486.PNG I am considering installing 5 amp low voltage disconnects on each of my 6 100 watt Renogy solar panels to isolate each panel that might be shaded and not producing 12+ volts.

The rationale behind this is to boost the output voltage of the 6 panels that are wired in parallel. I do have trees that are causing shade on the panels in the morning and in the evening. After many searches of the internet I have found no information about this concept.

My question to the experts is has anybody tried this and will this work? Are there any disadvantages to having shaded low output panels automatically taken offline until the are outputting 12+ volts?

The ultimate goal is to increase the output of my solar panel array.

The system currently consists of 6 12 volt panels wired in parallel to a Renogy Wanderer charge controller, a Morningstar TS-45 charge controller and an inverter all also wired in parallel to the panels. There are 2 charge controllers one to charge 4 120 Ahr Deep cycle batteries from Walmart and the other to charge a bank of sealed deep cycle batteries.

Thank you for any feedback that can be provided!

[bcroe]

Opening the circuit on a live DC power circuit is to be avoided if possible; even my test stuff draws quite an arc.
Your panels already have bypass diodes to take out the shaded sections, these might lose 1V per panel
section or 3V total with 3 diodes.

If you want the 3V back, I would suggest using a power MOSFET to short out the shaded section. It would
only handle perhaps 12V/ 8A, not both at the same time, not much power. It won't hurt the panel or cause
any ugly connect / disconnect problems. The bigger problem might be determining just when is the right
time to switch it on of off; I believe one of the big semiconductor cos actually came up with a device to
solve this problem, more research.

The above applies to the series connected panels you mentioned. Bruce Roe

[SunEagle]

If your panels are all wired in "parallel" then if one stops producing (due to shade) it should not affect the voltage output of the others.

Now if those panels are wired in "series" then disconnecting one will drop the voltage going to the CC more than if the panel was just shaded.

So I do not see a reason to install a disconnect device on those panels to remove them just because of shade.

But if you have more than 2 panels wired in parallel you will need overcurrent protection (circuit breaker or fuse) for each panel per the electric code.

As for your system using 2 different CC connected to 2 different battery systems, I would say that you are losing more than 33% of that 600 watts because you are using PWM CC's which more than likely will not be enough to charge both battery system.

[Mike90250]

Shaded panels still produce voltage. When the amount of light is low, the amps the panel can produce, goes way way down. No need to disconnect panels.

Here's some chatter about FET's as bypass diodes internal to a panel, or as panels wired in series:

https://www.digikey.com/en/articles/techzone/2013/dec/maximizing-the-output-from-solar-modules

https://www.digikey.com/en/articles/techzone/2012/dec/active-bypass-diodes-improve-solar-panel-efficiency-and-performance

[Wy_White_Wolf]

Do the Renogy panels have built in by-pass diodes?

If so your trying to solve a problem that has already been solved.

WWW

[Sunking]

Amend, you are wasting your time for a problem that does not exist.

[Mawrazen]

Thank you everyone for your quick and knowledge answers. Sometimes I am my own worst enemy and tend to overthink things. Also I mentioned series on the panels in my original post. I have edited it to reflect reality which is 6 100 watt panels in parallel.

Thanks again and sorry for the confusion.

[Mawrazen]

SunEagle mentioned this earlier "But if you have more than 2 panels wired in parallel you will need overcurrent protection (circuit breaker or fuse) for each panel per the electric code."

I will ill admit that I am new to this game and know enough to be dangerous. I currently have a 30 amp circuit breaker or inline fuse between my 6 panels wired in parallel and each load on the circuit (2 PWM CCs and 1 inverter) Will a 5 amp inline fuse on each panel be more compliant to code? The max output of each panel is a little over 5 amps but since they are not installed facing due South my output is somewhat less than optimal. My maximum measured current to date is anout 25 amp.

While I'm at it, Am I better off having dedicated panels for each load or am I ok sharing the panels between my CCs and inverter? Thanks again!

[Mawrazen]

IMG_6492.PNG Here are a couple of pics of my current set up. IMG_6493.PNG

[littleharbor]

The fuse rating should be on the label on the back of the panels. Fusing is intended to protect the wire, Best to use the fuse rating.

[Mike90250]

The fuse rating should be on the label on the back of the panels. Fusing is intended to protect the wire, Best to use the fuse rating.

That close, but not completely right. When you parallel PV panels. protection is required when you have more than 2 panels. If a panel goes bad, 2 panels can push enough power into the dud, to ignite it. That's why the PANEL sticker has the Series Fuse spec. The 12 or 10 ga wire has a 20A or 30A rating, most panels call for 6-15A protection.

[littleharbor]

That close, but not completely right. When you parallel PV panels. protection is required when you have more than 2 panels. If a panel goes bad, 2 panels can push enough power into the dud, to ignite it. That's why the PANEL sticker has the Series Fuse spec. The 12 or 10 ga wire has a 20A or 30A rating, most panels call for 6-15A protection.

I stand corrected. , Generally speaking, fusing is for the protection of the wire. Not in this case. Thanks for the clarification.