Likely better to do in a split configuration so you can balance the temperature coefficient to fall within a safe VOC range for each input. For example if you strung 4 together in series, then decided to buy a 5th, in extreme cold you would be pushing near the 150V VOC limit. However if you had a 3 + 2 configuration, you are well within 12-150V DC range (since the AC300 has two MPPT controllers at 12-150V DC). In other words the panels would operate at around 23V in the summer, but could go as high as 28V in extreme cold, and 28X5= 140, very close to the limit.
There’s no concern in connecting the 4 panels in series to DC1.
If you’re referring to RSP220DT they are VoC 21.86 V and SCC at 13.41 A so your only feasible option it will be to connect them 4S1P so 4 in series to DC1. This way you will input at 87,44 V and 13.41 A so you will be staying under voltage limit and you will slightly overflow current limit of 12 A which is totally fine.
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At that point if DC2 is left unused, you could benefit of PV parallel mode which you can enable from the settings menu and by connecting your array to both DC1 and DC2. With parallel mode you will have a very little increment in production since your 13.41 A would be split between the two channels. With parallel mode disabled you will be limited to 12 A out of 13.41 since the two channels of the AC300 have a 12 A limit each.
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If you connect only 2 panels in series your voltage will be 43,72 V maximum which is lower then nominal battery voltage (48 V, typical 51) so the MPPT solar charge controller of the AC300 will work in boost mode with a naturally lower efficiency.
Changing tack slightly. Looking at connecting a pair (2) of these panels in series to DC1
ET Solar Elite 440Watt Solar Panel Bifacial Monocrystalline Full Black Panels (SKU: ET-NR748TBH440GB)
Elite 440Watt Solar Panel Bifacial Monocrystalline 26% Efficiency - Fu – VoltaconSolar
Would leave DC2 unused, with potential for connecting future panels
Has anyone had experience with the ET Solar panels?
Is my plan to use a pair of them with my AC300+B300K combo, sound or BSC?
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