Any issues using a larger than necessary mppt SCC?

[Solarfun4jim]

It is my intention to purchase a SCC which is larger than needed for my current panel wattage, with the view i might add another panel later to the string.
Current panel wattage is 740W on a 24v system. Was looking at purchasing a 150/45 Mppt SCC. (i really should only need a 100/30)
Any issues in the fact my current panel array could only produce a max of 30A and probably much less? I'm assuming the Mppt function of SCC can handle this just fine without to much loss of efficiency?
Opinions please?

 

[chrisski]

I think that’s a reasonable amount above what you need for growth. I purchased 100/50 for a system I only need a 100/30 for. If I grow the system, I won’t need another SCC.

The only comment I will make is the amps portion is also an amps out limit, which with 740 watts at 24 volts, I don’t think you’ll hit. My battery bank for my 440 AH and a 13% charge rate can take 52 amps.

 

[Solarfun4jim]

I think that’s a reasonable amount above what you need for growth. I purchased 100/50 for a system I only need a 100/30 for. If I grow the system, I won’t need another SCC.

The only comment I will make is the amps portion is also an amps out limit, which with 740 watts at 24 volts, I don’t think you’ll hit. My battery bank for my 440 AH and a 13% charge rate can take 52 amps.

Thanks. i just needed to confirm that the 45A is the output limit, but there is minimal loss of efficiency only supplying say 11A from the panels max(in series).

 

[chrisski]

Thanks. i just needed to confirm that the 45A is the output limit, but there is minimal loss of efficiency only supplying say 11A from the panels max(in series).

You’re correct.

If you’re getting 11 amps from the 24 volt panels for a 24 volt battery system, the Panels probably actually Produce around 36 volts, and the charge controller may bump that up a few amps to 24 volts 16 amps, which is still well below the 45 amp limit.

EDIT: For a efficiency loss in stepping up in amps, I don’t know for sure. I looked in the Victron Data for my controller, but it did not mention it. Other posts I’ve found says its minimal.