Out of curiosity, you have optimizers because:
a) the commune was established
b) there is shading of the roof
c) it is required by the fire protection agreement
rutekjery wrote: 2. Taking into account the above and the parameters of the panels and the inverter, am I correctly calculating that adding two additional identical panels is fully acceptable and safe? The operating voltage range of the inverter is 140 - 980 V. 20 panels with an open circuit voltage (Voc/V) of 49.3 V give us a total of 986 V, which means that in theory I exceed the range by only 6 V. The maximum input voltage of the inverter is 1100 V.
I`ll start the answer from the other side...
This means that the open circuit voltage < max input voltage. You should not practically reach the maximum open circuit voltage, because when the inverter switches on the production, the voltage drops.
And now the second part of the answer... The panels do not have to be identical because you have optimizers. It would be good if they were similar in terms of parameters, and of course I recommend using optimizers. 2 pieces don`t cost a fortune and in the event of (knock on wood) fire etc. you have a voltage-free circuit. The voltage occurs in the panel-optimizer circuit and is approximately 50V.
And if you already have such a system with optimizers, the maximum voltage does not really concern you, because the voltage behind the optimizer is completely different than on the panel.
Take a look at the instantaneous voltage (of course, divide the string voltage into the number of panels), the instantaneous current and the instantaneous power... it doesn`t compare with the panel power diagram. ;)
rutekjery wrote: 3. If I wanted to add 4 panels and achieve a total power of 9.9 kWP, is the only option to add cabling and divide it into two strings?
This solution makes little sense, especially since with 4 panels you need 4 more optimisers and the profit will not be proportional at all. Practice says that the panel power = 115% of the inverter power (assuming that the inverter absorbs 10% more, and this is almost standard).
So your result is 9.2, so I wouldn`t go for 4 panels, considering that it still requires a lot of modifications to the roof.
rutekjery wrote: 4. I found practically identical panels at a very good price, i.e. LR4-72HPH-460, i.e. 460W instead of 450. Can adding 2 pieces in this single string cause any problems, but I assume that I would also use optimizers for them
Yes and no :]
I suggest setting up with optimizers (of course, use the optimizers in the P version, not P2). And here is the problem, because the optimizers were in the 450 version, so 10W less. There are 600W optimizers, but I don`t know if they are compatible with 450, I haven`t had a chance to mix them. However, they appear in the datasheet of the 450-P2, so it may be different.
Coming back to the optimizers 460W/450W = 1.022222222, i.e. 2% more, exceeded, but I think it should be at a safe level.
Once I got through all this, I read....
rutekjery wrote: Can adding 2 pieces in this single string cause any problems, and I assume I would also use optimizers for them?
....ehhh and all you had to do was reply YES :)
P.S.
Of course, any exceeding of parameters always means working beyond the limits specified by the manufacturer. So you may have problems with the warranty, or something may break, etc... but if the limit is <5% it should be ok. as my friend so helpfully pointed out...
jsw wrote: 2/ the maximum panel power for 450W-P and 450W-P2 is the same and is 472.5W and for 600W-P 630W
so it will be OK.
I have already seen installations that, in principle, should not work, or should burn during startup, but they worked, let me tell you more... even an installer with a D/E stamp was able to sign it
. Let me just say one thing: the panel has such characteristics that the colder it is, the higher its voltage and, consequently, the better its efficiency. Often around March/April it can reach in peaks of a few minutes above what is shown on the catalog card, and in June it is already below :]
