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separate solar strings facing different directions on a single charge controller?

Cuteajax

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What will be the effect if I combine separate solar strings facing different directions on a single charge controller? Will I get the average of both outputs or less? The orientation of my roof can only allow me to separate my arrays. Please advice. I have 6 units of 330 watts solar panels and a single Midnite Classic 200 charge controller.
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It is actually reasonably common to use multiple strings in different directions.
Connect the different strings in parallel. If 3 or more strings, you need to fuse each string before your parallel junction.
And fuse/wire for max possible amps at any one time.
 
What will be the effect if I combine separate solar strings facing different directions on a single charge controller? Will I get the average of both outputs or less?
By paralleling arrays the current will be higher from the array facing the sun and lower from the one that isn't. That's the nice thing about putting arrays in parallel like this - the current from each adds up.

So in the morning, the east array will generate most power while west is supplying less, so yes it will be the average of the two but that's because one is getting good sun while the other isn't. It would also be the average of the two if they were each on separate charge controllers/MPPTs.

In the middle of the day they will both be contributing roughly equally, the in the afternoon the west array will generate most.

It's a really nice way to layout arrays, as it flattens out and widens the production curve across the day, reducing the peak in the middle of the day. This can advantageous, especially if the potential peak output from a single orientation array is higher than your system can productively use.

Since both arrays are connected to the same MPPT they will be operating at the same voltage, so that will be a little sub-optimal compared with having separate charge controllers or MPPT inputs, but a decent MPPT will still settle on a voltage which generates the highest power output overall and because one array is facing the sun the voltage will naturally favour the array with the best production conditions. It might be you lose some production potential from the array not facing the sun, but since it's only going to be generating a minor contribution at that time anyway, you're not losing much overall. It will represent less than a handful of % compared with having separate charge controllers. Usually just having a slightly higher rated panel is more than sufficient to make up for any small losses.

My only suggestion when paralleling arrays is for each string to be of the same number of panels of the same rating. So e.g. use 3S2P, or 2S3P but not 4S+2S for instance.

If 3 or more strings, you need to fuse each string before your parallel junction.
And fuse/wire for max possible amps at any one time.
This.

A combiner box can make the task easier for combining more than 2 strings.

And of course make sure about voltage for the strings being connected are suitable for the charge controller's limits.
 
I've been doing it now for years. There is some talk about how different arrays might operate at different temperatures, and might present different voltages to the controller, causing it to be confused; but in my own situation, I've never observed this in several years of operation. I am though operating with Midnight200 controllers, so this might be a problem only for the entry level, budget controllers, that may have simpler charging programming. I would say you are good to go.
 
I am laying out plans for two separate systems. One is already up and running and the other is in the planning stage.

I would add to what has been said, different directions AND over panel. Midnite Solar told me overpaneling is no problem for the classics as long as you stay with in VOC. I would say, try to use same / similar panels, and same number in each string. Try to keep the VOC as close as possible for each string.

My Midnite Classic 150 currently has 9 285w panels, I am going to up that to 18 just to catch different angles, cloud days and morning / Evening potential. Midnite Solar Tech told me this was no problem at all. The only setting change i will make is to limit the Max Output current to probably 85 amps down from 94 amps (which is the classics 150s output for a 24v system). With so many panels it will be running wide open for a good bit of the mid day. So do not want heat to be an issue

In the system we are building we plan to use a Growatt 12kw 250vdc that has 2 separate PV inputs, 60 amps charging each. Same idea as above. Overpanel to maximize clouds, morning / evening. When we're done will have way too many panels, but we will be running 2 home runs, so we can easily add a 2nd charge controller if we find the batteries struggle to get recharged.

I would say do what the folks above have said. Great Ideas, and consider overpaneling to optimize charging for adverse conditions.
 
I recently installed a system with 4 strings of 750 watts each. One string faces east, 2 face south, and 1 faces west - all are mounted vertically on the exterior siding of my guest cabin. Each string goes through a MNEPV breaker before being combined in parallel to a Victron 150/70 CC. Seems to be working great so far.
 
I have the same question. 3 strings of 3 modules/3s3p. (750watts per string). Hypothectially at 8 am with string A pointing 135 degrees producing 400watts, string B 180 degrees producing 160watts and string C 225 degrees producing 30 watts, all tilted 45 degrees on ground mount. I have a tristar mppt 60. When I asked morningstar about over paneling a 24v system they said:

" On a 24 volt system this would be 150% over capacity which will not harm the controller."

"When segments of the array are in different orientations, the voltage and current variations between the segments will make it very difficult for the Tristar to max power point track the array which will reduce your energy production"

Does anyone know how much energy production we lose caused by different orientations? Excluding wiring losses, would I not see about 24-25amps comming out of the controller? 400+160+30= 590watts produced/24v= 24.58amps.
 
The strings that are not facing the sun, are going to pull some of the power from the ones that are. You should have blocking diodes on each string.
This will guarantee that all available power gets to the SCC.
 
I am not sure I am losing any production by the strings not seeing the sun. I can turn off breakers for each string and I don't really notice a difference either way, but hard to know for sure because power always bouncing around. Its worked great for me all winter and so awesome not to worry about snow killing production here in Wisconsin.

If you want to play around with total production, I recomend NREL's PV watt program.
 
The next strings that I will be installing, will be on the other side of the roof. I already have the diodes, for this purpose. Over paneling for cloudy days and winter, is also my goal.
 
The next strings that I will be installing, will be on the other side of the roof. I already have the diodes, for this purpose. Over paneling for cloudy days and winter, is also my goal.
How do you calculate the power you would lose if you didnt install the diodes? Is Isolating each string with a breaker and testing in full sun the only way to really know?
 
How do you calculate the power you would lose if you didnt install the diodes? Is Isolating each string with a breaker and testing in full sun the only way to really know?
Probably
But, would be hard to mimic the exact same amount of sunlight, at different times of the day, on different panels. My clamp meter can show which direction the current is flowing.
The basic understanding is that whatever the difference between the two arrays is, is equalized and approximately half of it is lost.
 
Most newer panels will have the rating for the backflow blocking (diodes) in their specs. I run QCell G10's and G6's, both of which have blocking diodes built in them. If they don't state this in their specs, they might not have it.
 
Most newer panels will have the rating for the backflow blocking (diodes) in their specs. I run QCell G10's and G6's, both of which have blocking diodes built in them. If they don't state this in their specs, they might not have it.
Those aren't blocking diodes. They're bypass diodes.
Backflow (if any exists) goes directly through the cells.
 
Hello- I have 1 HQST 40a MPPT & 4 panels total:

2 Canadian Solar 400w (52.3 VOC & 9.9 ISC)

2 REC 370W (44.1 VOC & 10.55 ISC)

Due to space constraints, I will need to have 2 panels facing West and 2 panels facing South. Being they are facing different orientations, I want to lose the least amount of production. I already know due to the panel types being different, I will lose some production due to VOC dropping to lowest in series or ISC dropping to lowest in parallel. I know that the best way to do this is to have panels of the same orientation on its own MPPT.

However if I were to want to remain with just the one MPPT what is the next best way to wire these panels? Can I Just parallel all 4 panels together? Thanks for taking the time to read this. Your help is much appreciated, Happy New year!
 
If one string has less light, how is the SOC able to track it down to a lower voltage(max power point for conditions) while at the same time keeping the other string at a higher voltage?
 
However if I were to want to remain with just the one MPPT what is the next best way to wire these panels? Can I Just parallel all 4 panels together?
Yes however you need to know if the single panel voltage is high enough for the MPPT, else just go with 2 x parallel strings of 2 panels in series. One string west, one south.
 
Can I Just parallel all 4 panels together?
You would need to use something like a combiner box because MC4 connectors are 30A max.

If your SCC max input voltage is over 100Voc (or it never gets much below 25C/77F), then 2S2P is likely the best:
Combine one of each panel in series, facing in the same direction (do this twice to make 2 strings). Then combine the strings in parallel for the least amount of loss.
You only need a pair of Y connectors and you've got a good setup.
 
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