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Need help figuring out solar panel wiring configuration

SolarHead

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I have 32 solar panels, 14 of one brand, and 18 of another brand. I plan to use a Sol-Ark 12K which has TWO MPPT controllers so I'm assuming I will end up splitting the two brands into the two MPPT controllers. I need help figuring out how best to configure the wiring, series, parallel and/or series/parallel. I dont want to cook my wires, nor cook the Sol-Ark. I think Sol-Ark has a solar panel calculator but I don't really know what I'm doing or have the confidence to KNOW that I am doing it right. What do you recommend I do?
 
First thing is to get the Sol-Ark specification sheet and find the following. Max Voc input, MPPT voltage range, min start up voltage and maximum amperage at each MPPT input. Keep in mind, on some brands the total Maximum PV wattage for both inputs combined may be lower than the maximum for each individually.
Next, get the info for both brands of solar panels. Voltage, Current Etc. and most importantly the temp/voltage coefficient. It is a negative number that tells us how much the panel voltage increases as temperature goes down.
Please post the above info and we can help.
 
Taken from the user install manual:
Sol-Ark 12K has dual MPPT.
Max PV Input 13,000W (+/- 5%) per system (6,500W per MPPT) PV = 500 Voc Max
Max Isc input per MPPT: 25A (self-limiting to 20A @ 450Voc/300Vmp or 18A @ 500Voc/400Vmp
Damage will occur if PV Voc > 550V (needs 150V minimum)
Parallel strings per MPPT must be same voltage.

Panels 32 total
------------------------------------------------
(14 count) Canadian Solar CS3K-305MS-BLACK
(18 count) Mission Solar MSE320SR8T 320WP
I plan to mount all 32 on a single ground mount 2 rows tall and 16 wide.

This is available online but not sure I know what I'm doing with it to feel confident


canadiansolar.png

missionsolar.png
 
Modeling this as two different batteries with different voltages & capacities, I would not parallel them.

Assuming each panel + MPPT gives you some voltage at some current, I'd put the MPPT outputs in series.

The downstream "things" then have to handle Max MPPT voltage 1 + Max MPPT voltage 2, at some current & the sum of panel powers.

However, the built-in MPPT intelligence & circuitry may handle this somehow for a series or parallel connection.

OEM block diagrams for various configs would help, 1 pic = 1000 words, even as just a cross-check.
 
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I think what would be nice is a diagram, hand-drawn is fine, that shows how best to wire the 2 strings (assuming 2 is all I will want/need). I'm more of a visual person when it comes to learning.
 
Based on what you posted it looks like the configuration shown on page 21 of the Sol-Ark 12K will work for you. It will consist of 4 strings in a 2S2P configuration.
PV1A & PV1B will be 2 rows of 7 Canadian Solar panels and PV2A & PV2B will be 2 rows of 9 Mission Solar Panels. They can be arranged exactly as you mentioned, 2 rows of 16. Each row will have 7 Canadian Solar panels and 9 Mission Solar Panels.

PV1 has the following specs. Vmp (NMOT per datasheet) = 210V; Imp (NMOT per datasheet) = 15A (7.5A x 2); Voc =276V; Voc @0 deg. C. = 296V
PV2 has the following specs. Vmp (NMOT Estimated) =220V; Imp (NMOT Estimated) = 15A (7.5A x 2); Voc = 397V; Voc @0 deg. C. = 393V
NOTE: the voltage of strings PV1 & PV2 do not have to be the same since they are on separate MPPT inputs. Its the A & B strings that are paralleled into a single MPPT input that have to me matched per the datasheet.

I would NOT use the Y connector as shown. Instead use a DIN rail breaker/combiner box attached to the framework of your ground mount structure to make the transition to the single + and - conductors for each of the 2 MPPT inputs on the Inverter. Dave Poz has done a very good job of covering this subject on YT.

Its a time consuming process to source all the components and draw it all out. If you need more help feel free to reply to this post or reply with a private message. We can work through it but I don't want to waste our time covering stuff you already know.
 
For what it's worth, I have four of that same model of Mission Solar panels. They are working great for me. I'm planning to buy a couple more.
 
BentleyJ - Thank you VERY MUCH for the help! I figured prepare a diagram and let you look over it to make sure I am completely understanding. Of course I would mount all 32 panels on one ground mount rack all side-by-side, I just have them separated on the drawing for clarity. Let me know if this is what you have in mind. It sure seems to keep the voltage and amperage within the limits of each MPPT.

Also, I can't remember but was thinking the Sol-Ark manual stated something about MPPT2 could not do as much voltage as MPPT1 but it was very close, maybe I'm wrong, I'll go back and verify with Sol-Ark (or the user manual) and if that's the case, I would put the higher voltage array (the Mission Solars) on the MPPT that can handle the higher voltage. Now if I can just find a ground mount kit that doesn't cost me a kidney and a lung. Might be treated wood at Home Depot if I can't find an affordable factory-made rack.

array_design.png
 
I forgot to mention, I'm thinking that the Midnite Solar MNPV10-1000 would be a good box. A bit pricey but it handles 1000V from what I can tell and would allow for expansion in future if I expand my array. Do you think this box would do what I'm wanting to do?
 
Nice diagram. As far as the ground mount, nothing wrong with pressure treated wood, its going to be a bit bulkier looking than using something like round or square tubular steel. The midnight solar combiner box will certainly work. Based on the rather high pricing, I would seriously consider something like this. Disclaimer, I have no personal experience with this product.

Personally I like breakers better than fuses simply because fuses do wear out over time even if they are not overloaded.

The voltage drop for 200' of 10ga wire carrying 15A is 1.5% which is acceptable. 8ga would be 1%. Cost wise probably the 10ga is the best choice especially since 15A is the peak current and will not always be that high. Voltage drop is proportional to current so at 10A VD on the same 200' of 10ga wire is only 1% instead of 1.5%.
 
I've discovered that warehouse 20 foot tall uprights can be found online (Craiglist, etc) for fairly cheap and they have holes that line up well with unistrut holes magically. So, I'm experimenting with this and very little fabrication it seems. I did weld some hinges to it so I can tilt/adjust for winter and summer. I figured 6x6 treated posts in ground, hang the upright horizontally and I can get 9 panels on one upright.

upright.jpg
 
I figured breakers would be better than fuses as well. With fuses you have to have some on hand for emergencies. Plus, I can kind of use the breakers as a disconnect at the array. Inside the house I got a 200A load center identical to the panel box I already have that way I can simply move the breakers over to the critical loads panel when I'm ready to wire this thing up. I figured some wago connectors and extend the wire, move the breakers over I want. I also think I can use a main breaker in the critical loads panel to shut off the entire panel if needed. I do plan to put in a safety switch (100A blade type) in between the inverter and its grid tie wire to my existing panel box (using a 60A breaker there per recommendation from Sol-Ark). I think with those in place, and Sol-Arks internal breakers I should be covered. I'm having fun so far but it has been a huge learning curve for me to step through. (still stepping through it). Thank you again for the help.
 
Sounds like a great project and you have put quite a bit of thought into it. No doubt will turn out very well.

Quick note regarding UniStrut. Its great stuff, we used thousands of feet on many commercial and industrial electrical installations. For outdoor use you may want to order a heavy galvanized finish. The standard off-the-shelf product may rust when outside unless you paint it or powder coat it.
 
BentleyJ
Per the above (posted again here for convenience)
PV1 has the following specs. Vmp (NMOT per datasheet) = 210V; Imp (NMOT per datasheet) = 15A (7.5A x 2); Voc =276V; Voc @0 deg. C. = 296V
PV2 has the following specs. Vmp (NMOT Estimated) =220V; Imp (NMOT Estimated) = 15A (7.5A x 2); Voc = 367V; Voc @0 deg. C. = 393V

What would be my ISC of each PV array? I was asking Midnite Solar about fuse sizes and they asked what was my ISC for each string. I assume they will size up for the fuses. I think I'm going with fuse holders, instead of breakers for the combiner box. Then go with some ISO DC isolator turn-switches to disconnect arrays if/when needed.
 
Isc = 9.9A & 10.0A per the respective Canadian Solar and Mission Solar datasheets supplied previously.
Please post some pics of your completed project.
 
Thank you. Yeah, I'm hoping in about 6 more weeks I will be ready to go live with it. Just trying to figure my way through disconnects and fuses required at this point. I'm looking at putting a MNSPD600 per string, but wondering if one per array would do it. I can't imagine buying 4 of those surge protectors and installing them on my combiner box @ $91 each. Then need to learn about grounding, Sol-Arks manual says do NOT ground the array and to ground the inverter (the 12k) only once so I may enlist an electrician to help me figure out grounding unless you know. I would be glad to pay you for the help you have provided thus far and future if you're interested. Seems solar companies, if commercial won't talk to you, if residential are so busy right now they only want the $60,000 jobs where they sell you the equipment and do the whole thing. The moment they find out I've already bought my panels and inverter they lose interest in talking with me. I emailed 5 residential solar companies last week and only one replied. Their reply was "sounds like you need to talk with my electrician who is $250/hour. Let us know and we can set you up on retainer". Having a DIY forum is pure awesome.
 
Well you've opened a real "can of worms" regarding the grounding issue. There are several threads with dozens of replies already on this forum so would prefer not to go into detail other than to say. You are located in Virginia so your installation needs be compliant with the NEC which requires ALL exposed metal components like the Solar Panel aluminum frames and mounting rails to be bonded to ground. Not sure what Sol-Ark is saying.

Licensed Contractors as a rule do not wish to work with DIY'ers so once you choose that path you have to rely on this yourself and forums like this.

Feel free to send me a private message if you would like more detailed input specific to your project.
 
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