TheProfessorBE
New Member
Hi there, and sorry, long post incomming. TL;DR at the end
I had a discussion with a (somewhat rude) employee of the company where I bought my DIY PV kit using a MIC1500TL-X inverter. I now have 5x 420Wp panels from Jinko installed (with a Voc of around 50V STC), and I wanted to add a sixth panel (yielding 2520Wp with 300Voc under STC)
The datasheet of the Growatt states a "Max. recommended PV power (for module STC)" for the inverter of 2100W. I asked the seller what that number means, because as far as I know, this recommendation is just that, a recommendation, because of the following reasons:
Furthermore, the (somewhat rude) sales rep told me that if I do that that 1) my connectors to the inverter would melt, and 2) that the Growatt warranty would be voided if I connected a sixth panel.
I pointed out that the melting thing is nonsense, and after some internal inquiry, they conceded with that. However, they still are adamant about point 2, that the warranty will be voided if I connect more than the "max recommended PV power" to the inverter. I cannot find any writing on the Growatt warranty card, manual, or datasheet that states that this is the case. I pointed out to them that it is written in the datasheet as a recommendation, not as an absolute maximum rating, to which they implied I do not know how to interpret datasheets.
So concretely, now I am want some input about the following two things:
I contacted Growatt, and they referred my inquiry to their engineering department.
TL;DR: why does growatt for their 1500W inverter state a "Max. recommended PV power (for module STC)" in their datasheet of 2100Wp, and what happens when I connect 2500Wp of solar panels to it, and more important, why?
I have read the document written by @FilterGuy , and there it is mentioned for a certain Growatt inverter, it is not allowed to overpanel. However, in the corresponding datasheet, the wording is "maximum PV power", and not "max Recommended PV power". But again, I still do wonder whether that actually holds true, because the MPPT cannot 'sense' in an easy manner how much PV power is connected to it.
I had a discussion with a (somewhat rude) employee of the company where I bought my DIY PV kit using a MIC1500TL-X inverter. I now have 5x 420Wp panels from Jinko installed (with a Voc of around 50V STC), and I wanted to add a sixth panel (yielding 2520Wp with 300Voc under STC)
The datasheet of the Growatt states a "Max. recommended PV power (for module STC)" for the inverter of 2100W. I asked the seller what that number means, because as far as I know, this recommendation is just that, a recommendation, because of the following reasons:
- The input voltage of the MPPT is the important limit to respect, because if that is exceeded, the input IGBTs of the MPPT will potentially fail. With my six panels, 300Voc STC is under 500V, so there is no issue here
- The potential of a PV system to generate a certain amount of power is not implying that this power is pushed into the inverter by the PV panels. Rather, power means an ability to perform a certain amount of work. Therefore, when keeping within the voltage range of the MPPT, the connected power does not really matter (except that it is very inefficient from a financial point of view).
Furthermore, the (somewhat rude) sales rep told me that if I do that that 1) my connectors to the inverter would melt, and 2) that the Growatt warranty would be voided if I connected a sixth panel.
I pointed out that the melting thing is nonsense, and after some internal inquiry, they conceded with that. However, they still are adamant about point 2, that the warranty will be voided if I connect more than the "max recommended PV power" to the inverter. I cannot find any writing on the Growatt warranty card, manual, or datasheet that states that this is the case. I pointed out to them that it is written in the datasheet as a recommendation, not as an absolute maximum rating, to which they implied I do not know how to interpret datasheets.
So concretely, now I am want some input about the following two things:
- Why would there be a maximum connected power rating in the datasheet? As long as I stay below the max input voltage, nothing bad can happen I would think? An analog here is that I can connect a 12V 100Ah car battery which can deliver 500A of current (6kW of power) to a small load of only 1W, without the small lamp burning into flames. Power is not pushed into the MPPT, but rather drawn out of the PV panels by the MPPT, as it flows through the AC inverter into the grid.
- If point 1 is correct, is there such a thing as voiding warranty if more PV power is connected (keeping in mind that, at all times, the max input voltage is respected)?
I contacted Growatt, and they referred my inquiry to their engineering department.
TL;DR: why does growatt for their 1500W inverter state a "Max. recommended PV power (for module STC)" in their datasheet of 2100Wp, and what happens when I connect 2500Wp of solar panels to it, and more important, why?
I have read the document written by @FilterGuy , and there it is mentioned for a certain Growatt inverter, it is not allowed to overpanel. However, in the corresponding datasheet, the wording is "maximum PV power", and not "max Recommended PV power". But again, I still do wonder whether that actually holds true, because the MPPT cannot 'sense' in an easy manner how much PV power is connected to it.
