28 panels. 3 MPPTs. Shading. Now what?

[WorldwideDave]

I just think you will have a lot of wire to roll up on grass cutting days

More like the extra cabling is being coiled up behind the battery box right now. Not all arrays are the same distance apart from the MPPTs. But the length of wire is the same from positive to negative on each array, so no weird stuff happening because one cable is 5' and the other is 100' or anything.

 

[sunsurfer]

Hello! I am trying to get the maximum out of my MPPTs and panel configuration. I think the goal is to push more current to recharge batteries. So parallelling more panels should be employed. This sound right?

I have 3 SCC MPPTs (250/70, 150/100, and 100/20) I am trying to get the maximum production out of them (all victron).
I have 28 panels, but 7 are in one array, and 6 are in another.
The rest I can lay on ground or lean against wall until I come up with a plan.
Panels are 200w. All figures are with winter overages/safety: 30.8 VOC, 8.6 ISC (amps).

7 panel array I have 2 series, 3 parallel, using 6 of them. They produce the most. In shade in morning and again in afternoon. This is currently connected to the 150/100 SCC. That is 62 V, 26 A in this arrangement. I have room for another 74A and 88V remaining available to that SCC. Most I can do safely is 3 series, 3 strings OR 2 series 4 strings OR 4 series 2 strings. Strings = parallel. This is 8 panels max, or 1600 W. I believe this is correct.

There is one panel on the end; right now that single panel is plugged into the 100/20. I could be paralleling another panel. That's it for this MPPT - that would be 62 VOC, 17 A. That one is done.

the 6 panel array is the 250/70, and is all in series right now. it has a lot of shade until about 12:30 in the afternoon, and even then has some shading on 1 of the panels pretty bad. I think this one is 185V, but just 9 A. That leaves 65V and over 60A still available to this SCC. I could parallel this 3 and 3 but probably better as 2s3p due to shading at one end. I also believe that this SCC can support 8 series 3 parallel with my panels.

I can also remove panels from the shady ends of both (or leave disconnected) as they are in the shade. However, I get about 500Wh from the single panel alone, so hesitant to remove that one.

Removing shading not an option - power pole and neighbor's hedge creating shade. Asked, but not going to cut it so I can produce more solar. I can move panels anywhere if needed (except roof due to permit).

I am open to suggestions.

I have 3 acres for sale in Missouri with plenty of sun area and some creek frontage. Even has a well and comes with a nice building. No permits needed. Only down side is you would have to live near me.

 

[WorldwideDave]

I have 3 acres for sale in Missouri with plenty of sun area and some creek frontage. Even has a well and comes with a nice building. No permits needed. Only down side is you would have to live near me.

Replace Missouri with just about any other state, and I'd be down But seriously - send me a DM with the information about the place. Friend in Branson looking to get out of the city.

 

[ericfx1984]

My new method for handling shade is more charge controllers to divide things up so the shaded ones are on their own controller. Your going to loose power to shade no matter what but with it being more subdivided amongst more controllers you can limit the penalty from it.

You just have to make sure the shaded stuff is on its own string.

I've been telling people this for a long time... And they just don't believe me

 

[WorldwideDave]

I've been telling people this for a long time... And they just don't believe me

Well, I think one of the challenges to implementing this is cost. For example, I paid about $18 per solar panel and I have 28 of them. However, the solar charge controller is around $400. Also, I think people want to try to work with what they have. Buying a low cost Y adapter to parallel strings and use a smaller solar charge Controller is a much lower barrier than buying an additional $400 solar charge controller. Also having multiple solar charge controllers isn’t as easy to configure. For example, now that I have three of them, the bulk, absorption, and float settings have to be changed on three devices versus one.

 

[ericfx1984]

Well, I think one of the challenges to implementing this is cost. For example, I paid about $18 per solar panel and I have 28 of them. However, the solar charge controller is around $400. Also, I think people want to try to work with what they have. Buying a low cost Y adapter to parallel strings and use a smaller solar charge Controller is a much lower barrier than buying an additional $400 solar charge controller. Also having multiple solar charge controllers isn’t as easy to configure. For example, now that I have three of them, the bulk, absorption, and float settings have to be changed on three devices versus one.

That's fair...