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Hello,
I am about to change my charge controller to a victron 250/85 smartsolar charge controller. I would like as high a voltage as possible going into the controller. I intend to connect 6 300w solar panels in series on the charge controller. 2 strings will then be connect in parallel for 12 panels in total. VMP of the panels is 38.80V, VOC is 44.16 and ISC is 8.93A.
Is this a safe arrangements or should I reduce panels in series to 5?
I assume you are feeding a 48V battery system. So at 3600W you will be feeding about 75A to the batteries. Six of the panels in series at 44.16VOC is about 264V, beyond the capacity of your controller. To maximize power production I would use 3 strings of 4 panels in series. This will keep your voltage within limits.
Pat
I use this to calculate. Just add your modules under under the modules tab.
(v3.1) - VE MPPT Calculator
Thank you everyone. If I go as high as 20 panels, can I comfortably do 5 panels in series for a total of 4 strings? The idea behind having a 250V charge controller is to go as high as possible in series so the charge controller wakes up early and goes to sleep late. I will also be feeding a very large bank and fully off grid.
So, is 5 panels in series a good idea?
Think we need to slow down a bit. If you go to 20 300W panels, that is 6000 or more (depending on the temperature),Watts of power. Now you are exceeding the amperage limitation of your controller. Not on the PV side but on the battery side.
For this large of a system I strongly recommend that you consult a Victron Certified Installer to assist you in designing and installing the complete system.
There are life safety issues, not to mention the financial impact if it is done incorrectly.
Pat
The 250/100 will simply limit itself to 100A into 48V nominal. In practice that may reach (say) 58V, so 5800W. 20x of those panels would rarely reach that, and would just 'clip' if they did.
We've discussed max string Voc, but the other thing to watch for is total string Isc. In this case, 5x 8.93 = 45A (My bad, edited to 4x 8.93 = 36A). Well under the 70A spec of that mppt.
'Overclocking' pv W is often standard procedure, and quite safe providing those other constraints are respected.
Not saying a Victron installer shouldn't be consulted/commissioned, but all should be sweet.
