Help understanding ONE string for exterior garage (gable facing due South) Panels on both sides of roof

[timselectric]

A mini-experiment of what you want to do.
Connect 2 identical panels in parallel. Put one in the sun and cover the other with a blanket.
Measure if any panel conducts current.
Post your findings.

That would require a very small MPPT.

 

[Phil.g00]

Who mentioned an MPPT?
An MPPT would only lower the voltage. If the shaded panel won't conduct under the most extreme condition, it won't conduct at lower MPPT voltages.

 

[timselectric]

If you want the results to tell you if it will make a difference, when connected to your (MPPT) system.
Otherwise, you'll be comparing apples to oranges.

 

[WindWizard]

They have:
Specifications:
Rated Current: 30A
Rated Voltage:1000V DC

So, it appears that this would work fine for me. Am I missing something? Be sure to click 30A after going to link and scroll down to specs:

https://www.amazon.com/dp/B09SP4VJLZ/ref=cm_sw_r_cp_apann_glt_i_A03KMCHNEJ4JEWR77GYP?th=1

Keep in mind that the diodes from this link are 45 volt reverse max voltage. I found that in my system it did not make any difference whether the diodes were there or not. I am using three panels that are connected in series times 4. I shaded one panel in the set of three and the other 3 panels sets kept producing with normal power so I decided not to bother looking for 200 volt diodes for my system.

 

[Kornbread]

I'm not having any luck finding others available.
Waiting on a email from a possible option.

What about something like this? Mouser 30a to220 diode
Never mind, 200v reverse current vs ops' ~300v.

 

[timselectric]

What about something like this? Mouser 30a to220 diode

Sure
But, I'm looking for the mc4 connector type.
That one would require a box.

 

[Kornbread]

Sure
But, I'm looking for the mc4 connector type.
That one would require a box.

Check out the amazon review Amazon review mc4 blocking diode With some finagling, it fits inside the connector.

 

[timselectric]

I'll be needing some blocking diodes for the next phase of my installation. If I can't find pre made units, that are rated for at least 500v. I'll make my own, from mc4 fuse holders.

 

[Kornbread]

I'll be needing some blocking diodes for the next phase of my installation. If I can't find pre made units, that are rated for at least 500v. I'll make my own, from mc4 fuse holders.

Interested. What are your plans?

 

[Phil.g00]

If you want the results to tell you if it will make a difference, when connected to your (MPPT) system.
Otherwise, you'll be comparing apples to oranges.

If you must, a simple resistor would be sufficient to load the panels.
You can approximate the resistance easy enough as the Imp and Vmp are on the label.
But then let's not hear the argument, "but at higher voltages.....".

 

[timselectric]

Interested. What are your plans?

More panels on other slope of roof.
On a separate charger, to just charge batteries in the summer.
But paralleled in the winter, with other slope. To increase input to inverter.

 

[RevMikeB]

A mini-experiment of what you want to do.
Connect 2 identical panels in parallel. Put one in the sun and cover the other with a blanket.
Measure if any panel conducts current.
Post your findings.

I would if I had the panels. I'm still in the planning phase.

 

[RevMikeB]

Keep in mind that the diodes from this link are 45 volt reverse max voltage. I found that in my system it did not make any difference whether the diodes were there or not. I am using three panels that are connected in series times 4. I shaded one panel in the set of three and the other 3 panels sets kept producing with normal power so I decided not to bother looking for 200 volt diodes for my system.

Well, the bigger problem I'm running into is that if I connect both sides of the garage in parallel after the blocking diodes, the amps increase beyond the limit of the inverter for that string.

 

[timselectric]

Well, the bigger problem I'm running into is that if I connect both sides of the garage in parallel after the blocking diodes, the amps increase beyond the limit of the inverter for that string.

Well, you can just connect them all in series and accept that they won't be as efficient as the other strings. But, you will still get some power throughout the whole day.
With the best output being at the sun's highest position.

 

[RevMikeB]

Well, you can just connect them all in series and accept that they won't be as efficient as the other strings. But, you will still get some power throughout the whole day.
With the best output being at the sun's highest position.

Honestly, I don't think there is another solution that I'm aware of. Just when I thought I had it figured out, boom; dust!!!

 

[RevMikeB]

Honestly, I don't think there is another solution that I'm aware of. Just when I thought I had it figured out, boom; dust!!!

Well, you can just connect them all in series and accept that they won't be as efficient as the other strings. But, you will still get some power throughout the whole day.
With the best output being at the sun's highest position.

Is it possible to use optimizers on ONLY one string (meaning both sides of the garage) without using them on the other 3 strings? I'm not sure if the inverter would be confused by that. I hate asking this question because of the cash register ringing louder.

 

[timselectric]

Honestly, I don't think there is another solution that I'm aware of. Just when I thought I had it figured out, boom; dust!!!

This is why we plan, before we install.
An eraser is less work than a jackhammer.

 

[timselectric]

Is it possible to use optimizers on ONLY one string (meaning both sides of the garage) without using them on the other 3 strings? I'm not sure if the inverter would be confused by that.

That's doable.
The optimizers work independently from the charge controller. It won't even know that they exist. It will just use the power it receives.

 

[RevMikeB]

That's doable.
The optimizers work independently from the charge controller. It won't even know that they exist. It will just use the power it receives.

Well, then why do inverters say that they support them, as if they might not? I guess it has to do with reporting the findings through Wifi so it can be seen/monitored by the owner?? So, if the panels didn't exceed the max specs for the inverter without the optimizers, then adding the optimizers won't change that, right?

 

[timselectric]

Well, then why do inverters say that they support them, as if they might not? I guess it has to do with reporting the findings through Wifi so it can be seen/monitored by the owner?? So, if the panels didn't exceed the max specs for the inverter without the optimizers, then adding the optimizers won't change that, right?

Correct