In practice, a PV array usually experiences uniform insolation or partially shaded condition? MPPT techniques must be adapted to wich one? uniform insolation or partially shaded conditions?
Max power transfer control logic is to extract the maximum power during all period, whether it is uniform insolation or partially shaded. If you have the V-I curve in any PV panel, the current pumping is increased or reduced(Basically perturberance is done) and the final power is computed. If the power reduces, the reverse is applied(ie. if we were "increasing the current extraction", and if we observe power getting reduced, we change to "reducing the current extraction" or vice-versa). Always extracting the max power from a PV panel is the purpose.
any change in the load or in the operating conditions, the maximum power point position is changes.So, it can be adapted to both cases.
Dear Mohan
What you are trying to describe, is named perturb & observe, and is considered as a classic MPPT technique. Its not my question. My questions is that when we are trying to develop a MPPT technique, uniform insolation must be prioritised or PSC? In practice, which one happens more?
Please elaborate further. it is unclear what you are after...
You are implying that you are working on an MPPT technique other than P&O
It is not clear how apriori knowledge of shading would be useful/practical.
Theoretically one could attempt to model the IV curves and account for
degree of shading and measure gross-insolation and like that, but
that seems like an N-body problem
One factor which occurs to me would be to possibly segment the array according to degrees of shading so that the entire array is not compromised by the partial shading of a few panels. Lump the "junk" together.
Ahmed, partially shaded solar arrays can show very strange I/V curves with more than one maximum power point. It is easier and less risky to design and position your array so that it doesn't get partially shaded. If partial shade can't be avoided, then configure the array as a number of independent circuits each one serving a number of panels of the same order of area as the shadows the array will have to cope with, and each circuit having a separate MPPT. You could usefully study my paper on partially shaded solar arrays. Best wishes!
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