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Hi,
I'm looking at the 250/70 for two strings. The are both on the same roof however one string will become completely (uniformly) shaded before the other as the sun moves around. (matching panels) Is the MPPT smart enough to apply different optimisations to the separate strings or will I see better performance from using 2 MPPTs instead? Advice appreciated!
It will be best to use 2 MPPTs instead; there is only one tracker in the 250/70 so it doesn't see two separate strings - it only has one input. It'll still get what it can, but you'll have much better production by using two MPPTs that track the strings independently.
If the difference in production (expressed in price) reported over the time period justify / overcome the price paid for an additional MPPT, then by all means...
On the other hand, since obviously a 250/70 wouldn't be needed for a single string, it would be two smaller and cheaper controllers.
The nature of the question was about performance, not price, so I stand by my answer.
You may be right.
Sorry, I am not an English speaker, so I was under the impression that he already had a 250/70 and started the reasoning from that point on and therefore telling him that he'd be OK.
Now I realize that the initial "I am looking at ..." is used as an expression before buying the product and in that case, indeed, it may be wise to use two smaller MPPTs.
Sorry...
Another thing .......
A solar panel has 2-3 sections, generally along the long side, each section with its own bypass diode.
For optimizing production, if you can, position the panels in that way that the individual sections inside a panel to be alongside the shadow track in order for the bypass diode of that section to effectively do its job.
In other words, for a single panel, to have an entire section bypassed and the other 1-2 to be productive, as opposite to have all sections partially shaded.
See below what I mean.
really helpful thanks - especially the shading diagram. thanks all for help.
You will have multiple MPPs on the power-voltage curve.
So if the Smart Solar is "smart" enough to scan for the "ideal" one, you'll be OK.
