Hi, I have just installed 2 arrays of 7 X 395W Canadian solar panels with a Tigo TS4-A-O on each panel totaling 14 optimizers. In low light I can get a VOC reading of approximately 250V and approximately 3A, as soon as the sunlight becomes more bright it drops of totally, ie, no volts or amps. The array on the shaded side still shows 250V with no amps which seems normal to me, can anyone help?
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I agree with you that this behavior is not normal. Do you have our CCA monitoring installed in the system, if yes we can easily understand the behavior of your system remotely.
I have created a support ticket for you, you will be required to send over additional information, such as the Inverter datasheet and string configuration diagram. Thus our Support agent will be able to identify a possible cause for this issue.
I have 20 panels newly fitted, all fitted with Optimizers, but no TAP or CCA, so I have no idea whether they are all working. I have noticed that in LOW light, my system underperforms by around 35%. Any thoughts as to why that might be?0
David, I am not sure about EU installs (I assume you are there since you used an S instead of the American Z in optimiser), but in the US, Tigo calls that blind deployment - using the optimizers without the monitoring equipment. It reduces the warranty to 5 years. I only bring this up since you said this is a new install.
Personally, I don't know why anyone would install a larger system like that and not want to know what was going on with it. I can pick up the CCA and TAP for about $350 to $400 US depending on where I get them from. If the homeowners state they are getting lower production then I can verify that. If you had that equipment, Tigo should be able to zoom in on what the issue is.
My first question is, how do you know the system is "underperforming" if it is new and you don't have monitoring?0
Matthias, Yes UK. My new 7.7kw system (with Tigo optimizers and facing slightly north of west) has produced less electricity than it should per the monthly breakdown of the annually generated figure as calculated by EPVS - the independent body who calculates this from lattitude, location, climate, and aspect, taking into account shading - effectively a regulator. I also have a 10 year old 5kw system (no optimizers) facing slightly south of east with its own EPVS figure. The old system performed better in relation to the EPVS figure than the new, by some margin. Also, in low light, such as near dusk. the old system (facing east) generates more energy than that the new one (facing west). The same was happening in January, when you need the best results you can get!0
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In John Loveridge's original description, he illustrates that there is a portion of the array "on the shaded side." The first question our Engineers would ask, is: "Are these strings wired in parallel, or in series?" This is a very important question, because shading equals resistance. The shortening of one parallel string (either physically, or by hard shading) will always affect the production of the opposing connected string, due to physics of Ohm's law.
If the shading is light, this balancing act can sometimes be improved by Tigo Optimizers. However, if there is complete black-out shading on one string, the affect pushes the Optimizers to try to keep both strings producing. In the end, this will negatively affect the production on the string that is facing full irradiance.
For more information on how Parallel Strings can be affected, check out these articles:
Designing your TS4 system for different tilts, angles, and orientation
Design Considerations for Uneven Parallel Strings
Matthias Oliver and David Hirst, this may be similar to what is happening on your systems. If you do have Parallel Strings, it's best if they face the same orientation and incur very little shading (from string to string). If this is not possible, then you may want to invest in an inverter that offers multiple MPPTs, so both strings can be wired in Series.
Lastly, have you reached out to Tigo's Customer Support Team? They can always review your system and/or design to see if there are production deficits that can be improved upon.0
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