The MPPT charger rating is the OUTPUT of the charge controller, and the input wattage is set by the battery bank voltage...
Eg my Sigineer SCC's are '150vdc, 60A' and have a 60A OUTPUT limit, and are 'multivoltage' ie on a 'nominal 12v'/12.7v battery bank have a 750W PV requirement- ie need 750W to make that 60A on a '12v' battery bank, 24v (1500W) and 48v (3kw)
(12.7v x 60A = 762W etc)
Basically all charge controllers can handle some slight overpanneling ie the wattage is above that needed minimum, some can handle quite large overpaneling (mine can handle up to 50%!!!), while cheaper ones often can't but can handle small amounts of overpaneling- but the voltage limit is a MUST- even going above it once and as Jim Carrey says in The Mask...
Although many SCC's are limited to the input current being the same as the output current (but that means the panel voltage is the same as the battery bank voltage)- as that is the poorest configuration in terms of daily generated power (you want your array voltage as HIGH as possible, allowing for the limitations of your controller)- I personally recommend going no higher than 80% of the PVmax rating, as solar panels can briefly exceed their 'label specs' (which only apply at STC) by 10-15%, leaving that 20% 'headroom' can save your charge controller WHEN those conditions happen (not if- when...)
You want the Voc for this- ie the 36.8v Voc figure- 4x 36.8v = 147v- which is OVER the 145v PVmax rating for the Growatt- this combination WILL fail in a VERY short time...
(note that they are at STC or standard test conditions- they will usually be a bit below the STC rating, but in certain conditions (ie light input goes up, or panel temp goes down) they can be ABOVE them!!!)
3 of those panels is the maximum in series that is safe longterm... 3x 36.8v=110.4v- a bit less than 116v- good match... (80% of 145v is 116v)
But you only have 4 panels- so 4S (4 in series is out), 4P will give you the worst charging performance and should be avoided (indeed with your panels having a 36.8v Voc and a Vmp of only 30.8v- your MPPT charge controller won't even get into MPPT mode at all (30v is the minimum needed for the Growwatt to run, and it will need at least 3-5v above that to 'start' the MPPT charge circuits!!!), leaving it running in PWM mode for much of the day and dropping your total daily generated power by up to 30% per day!!!- BIG lost production!!!)
So 2S2P is your only option in this case with your particular 4 panels....
That gives you 73.6v Voc (this system will be 'ok' in performance- not brilliant) as your Vmp is only 30.8v, the two in series is only 61.6v- good in bright sunny weather, total overall daily generation will be down a bit because of the low Mpp voltage in comparison to a 3S array, and poor weather production will also suffer...(you are well within the limits of the SCC - I don't know where you found that 22A pv input limit figure from, I have never seen it in any Growatt specs sheet ever and would cripple the controllers ability to use lower voltage arrays!!!!)
This is why doing the calculations BEFORE buying is a good idea lol)- buying 4 of those 400w panels is not a good choice- 6 panels with that particular Voc and Wattage in a 3S2P array is the best choice to match that particular combination of array voltages and charge controller limitations on a 24v system- thats 2000W on a 150v 80A MPPT controller for the controller, with an array Voc of 110.4v and a total array wattage of 2400W maximising both the controllers capabilities and panel output... but 'losing' some possible output in good conditions in exchange for maximising output in poorer conditions
(you may find that 'losing one panel' and going for a 3S string actually outperforms the 4 panels in a 2S2P arrangement!!!- lower total 'panel' wattage, but pushing the charge controller into a better performance envelope and making a higher total daily generation!!!)
Alternatively selecting a similar wattage panel with a higher Voc and Vmp would work in a 2S configuration ie 4x 400W to 430W panels in a 2S2P arrangement, but with a 50v to 60v Voc rather than your panels 36.8v...
eg something like this 430W Sunpower or similar would be a better choice for panels than yours for a 2S2P array on your Growwatt... if you set at that 4 panel limit (ie space restrictions)
Maximising an array to suit the charge controllers specs (or alternatively, selecting an appropriate charge controller for an arrays specifications) is a bit of a juggling act and requires knowing how they work and interact together...
which is why so many people stuff it up...
The manual for your Growatt with specs can be found
HERE (that table up above is from page 10)
