TS4-A-O different orientations - single string

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6 comments

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    Curtis Community Moderator

    Hello Jeff Turl

    Thank you for your contribution to the Tigo Community!

    The optimizers are created to balance out what they can, when in odd angles. However, splitting a short string of 4 panels into a 50/50 (hard east vs hard west) scenario, is quite a challenge (especially, if the inverter's minimum voltage requirement is more than 2 PV Modules of output)!

    In the article link that Marco Maljaars supplied, see the section on Acute Angles. It explains that the more acute an angle, the more difficult it is to balance out a split string (or 2 strings in parallel), due to the 25% Mismatch Rule. This is why Marco's 15 module East vs South (obtuse angle) system is functioning, while yours may not be.

    For your system design, this is what I'd expect to see: 

    • Early morning - The West units will not activate as they cannot contend with the Eastern units. This could cause the Inverter to start up very late, due to low voltage output (until there is enough indirect light to activate the western panels). 

    • Mid-to-Late morning -  A rocky start up of the inverter, as the Western units start to activate. Their output may be intermittent (as they struggle to match the output of the Eastern side). Every time this happens, it brings down the production on the Eastern side (due to resistance and Ohm's Law). This activity could also cause a few 'pops' on the inverter charting, as the MPPT wildly readjusts to find a point that matches the struggling output of all the units.

    • Mid Day - A flattened top to the desirable bell-curve, as both sides are functioning, but neither is providing a completely balanced output. The Inverter's MPPT has set a lower-than-expected power point to deal with this poor output balancing act.

    The rest of the day would be similar to the effects described above (but in reverse), as the Eastern units struggle to stay active in the ever-increasing hard shade conditions.

    The best possible resolution(s) to this activity, are:

    • Adjusting or moving the modules to face a more similar orientation
    • Splitting the series string into 2 independent strings, and wiring each to separate MPPTs

    In the meantime, adding more PV Modules to both sides of the string could possibly get the inverter to start earlier (if the 1/2 string does not provide enough voltage to start the inverter).

    If you ever need assistance in designing a system, please do not hesitate to reach out to our Sales Engineering Team. They will take the time to fully review your concepts, and advise you on building the most successful system possible.

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  • Avatar
    Marco Maljaars

    Hello Jeff,

    I have a similar setup on my A string.

    4 east and 4 south. All equipped with optimizers (8 in total).

    This is a normal setup and shouldn't be an issue. The string is performing as expected.

     

    Regards,

    Marco

     

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  • Avatar
    Jeff Turl

    I have Optimisers on all my panels, one has failed and when I contact support they are saying that Optimisers are not designed to be used this way. They have to be on the same orientation and by having on mixed orientation is the reason for the optimisers failure.

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  • Avatar
    Marco Maljaars

    Tigo is advertising this see example 2:

    https://support.tigoenergy.com/hc/en-us/articles/209345667-Different-Orientations

    However it is required to have a balanced system. Maybe that's not the case for your system.

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  • Avatar
    Jeff Turl

    I have a very small setup 2 panels on east and 2 on west elevation of a garage roof. I did point the person on support to that very article and I was told I can't do it and need two MPPTs and a string on each

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  • Avatar
    Tommaso Landi

    Hello Jeff,

    As per our phone conversation, your plant's design caught our attention with reference to a specific design rule and we just wanted to check with you whether that could explain the occurrence of the failure you reported.

    The very first step to solving a problem is indeed to fully understand its nature: that's why - being your plant not monitored through any CCA and TAP - we agreed you would answer a couple of questions for us to investigate further and help you solve your problem. Many thanks for your cooperation on that.

    Tigo shall continue supporting you on your existing technical support case or via phone, whenever necessary.

    Let me finally share with you an important piece of advice. Having a monitoring system installed at your plant would not just make it more complete or fun to interact with: panel-level monitoring gives you the ultimate, full control over such an important investment and it greatly facilitates any support activities on your plant.

    Being Tigo monitoring so powerful and useful, my suggestion is to have it added to your installation as soon as you can.

    Rest assured Tigo will always be there to offer you all the support needed. 

    Best Regards,

    Tommaso Landi

    Customer Success Director, EMEA

     

     

     

     

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