Troubleshooting non producing panel

I had my first component failure in my SolarEdge SE7600US/LG300 PV system after four years of nearly uninterrupted service. It was a faulty SolarEdge P300 panel optimizer. Once I contacted SolarEdge they quickly assessed the problem online and sent a replacement optimizer in a short time. Replacement took about one hour. Fortunately it was an easily accessible panel at one edge of a 16 panel array. The remaining ten panels on the string continued to produce power as if there was nothing wrong. Having this setup makes sense. I have only lost the production of one panel for a week rather than the whole string had I been using a string MPPT. The loss in production amounted to only about 1.8 kWh per day.

If you had a conventional string MPPT, you didn’t have a faulty panel optimizer.

Yes but he wouldn’t produce the same energy daily. This is the discussion about optimisers vs (multi) string mppt inverters.
The older my systems get, the more I personally appreciate the optimizers.
Tigo has done a good job to present the difference. They estimate the energy based on the worst panel on the string and they present the difference that you get because of the optimisers.


The above chart is from a 7 year old 10 kwp system that is partially shaded during the morning with an mppt inverter and tigo optimizers. The difference of the energy produced after the optimizer installation was evident in the first month.

In my case, there was a faulty panel (twice both on a tigo and a solaredge system) and the energy production was not interrupted.
Assuming that a technician would be available the same or the next day to troubleshoot the issue on an mppt inverter and bypass (if possible) the panel (or more panels depending on the mppt inverter), I expect that the cost of the technician would be much higher than the cost of the energy not produced by 1 panel in the case of optimisers.
I also had problems in a third system with mppt inverter where data was available only at mppt level and not at string level. In this case, you need to buy a dc clamp in order to find out which string is faulty and then start testing each and every panel to discover the faulty one. Good lack with this and prepare a good check for your technician.

With the per panel optimizer you are able to spot the panel that is not producing. I found that one panel had stopped producing and quickly contacted SolarEdge. They determined online that the optimizer was defective and not the panel. They sent me a new optimizer within a week, I replaced it and now the system is back to full capacity. The panel was not defective as the analysis showed.
IIio is correct, having panel level optimization is far better than string MMPT optimization. With the loss of a string optimizer you lose the production of the whole string.