What is the maximum number of Enphase M215 and S280s that fit on one string?
Visitor: I want to expand an existing install that I have that
has Enphase M215 inverters (9 on a brand), I wanted to add some S280s' but wanted
to know what the maximum qty of S280s is when added to the M215s?
Michele | RENVU: The maximum S280's and M215 on one string...that is a good question.
Richard strange: I know with just M215s its 17 but the s280's say 14
Michele: The scoop is the Amperage of each string is maximized at 80% of 20A (= 16A). 80% --> 20% reduction for a safety factor. 20A for the PV breaker that lands in the main panel and the max rating of the Enphase microinverters. (Note: Darfon microinverters have a 30A maximum.)
Each S280 microinverter has a Nominal Output Current @ 240V 1.13A, thus 14 units can be added to a string reaching an Amperage of 15.82A. Likewise each M215 has a Nominal Output Current @ 240V 0.9A, thus 17 units can be added to a string reaching an Amperage of 15.3A.
Following if there is a string of 12 M215’s this makes 10.8A. There is 6 A available to be utilized by future S280’s. In this example you could add 4 s280’s to the string. The ending amperage would be 15.32A.