3kw PV on Classic 150 at 24V

[SolarMusher]

Hi all,
I'm working on a 24V battery system that I would like to charge with a 3kw array (maybe at 90V) on a Classic 150. It would be a little higher than 100A to the battery bank (936Ah/20hr). Sizing tool gave me no more than 91A. Could I safely limit the Classic to say 90A? It's seems a little high to me. Is it safe to push a Classic to its limits on a yearly basis?
Thanks,
Erik
PS: It's a system upgrade, I would prefer to make it in a 48V config but there are really too much 12V and 24 devices (Pump, lights, fan, etc..)

[Vic]

Hi Erik,

To me,  this is just a bit too much current to expect from a single Classic,  especially if the String Vmp is in the 90 V range on a 24 volt battery system.

A lot depends on how much time the Classic spends delivering max current,  although  lightly-loaded PVs cause the Vin to rise,  and this is still a heat issue,  but the heat is from increased losses at the higher,  unloaded Vin,   IMO.

I had asked a similar question here,  a few years ago,  and it seemed to me that those counseling some moderation in maxing out a CC for possible extended periods were correct.   FWIW,  YMMV,  and so on.   Have Fun,     Vic

[tecnodave]

Eric,

I have to agree with Vic on this, I push my Classic 150 with 2240 watts 72 cell poly PV with 70 volt strings. The fans are running a lot at that power level. I'm trying to keep my average power level at about 60-70 % of max power to conserve electronics life.  I think the max rating for a Classic on 24 volt with 70 volt strings is 2700 watts so I'm at about 83 % max but usually more like 66% of capacity (1800 watts in) average solar input

td

[zoneblue]

LIke others said much will depend on whether you are overpanelled or not. If you are planning on charging at full tilt right through the middle of the day, thats quite different from being in float by 11am.

3kW of PV really puts you into 48v territory. In which case youll be right as rain, up to 4.5kW. You can get 48v to 12v dc converters now. Look on ebay. Dont let something like that dictate system voltage.

[SolarMusher]

Hi guys,
I asked yesterday this customer if it would be possible to change this Shurflo 24V DC pump for a Grundfoss SQ 240Vac to make this system 48Vdc and have better results on the water system. This 24VDC pump is actually working at 145 feet deep and there's no chance that it can supply the whole house. He told me to make it the more efficient, so I will go 48Vdc with a small converter to supply the 12Vdc loads he would still like to use (DC wiring is already done into the walls  ).
Talking about Classic limits, my CL200 is running with 3.2kw/107Vmp (48V system) but I prefer to keep it limited at 60A, anyway with a daily 10% DOD I'm in float by 12-13pm so it only reaches the 60A limit briefly and a few times in winter when DOD is deeper with a longer bulk charge.
Thanks for sharing your experiences!
Erik
PS: Hey Vic! hope all is fine in California 

[Vic]

Hi Erik,

Good news on the system design is going to 48 V,  that will make the life of the Classic 150 easy.

All here is fine.  But,  even in CA,  am running around trying to get things ready for Winter.

How are things there,  how are the dogs,   any snow yet

Have Fun!   Thanks.      Vic

[jimbo]

I have 3.1kw running on my classic 150 charging a 1600 amp, 24v bank, however 760w of those panels are facing NW and the others North.  It does hit 2.7kw sometimes but only for a short period.
Can you orientate your panels over 2 or 3 directions?

[boB]

I have 3.1kw running on my classic 150 charging a 1600 amp, 24v bank, however 760w of those panels are facing NW and the others North.  It does hit 2.7kw sometimes but only for a short period.
Can you orientate your panels over 2 or 3 directions?

Yes, you can orient your array sections any way you want.   Won't be as good as if all the PV is pointing towards
the sun, but it will work best that it can.  i.e.  there is still an optimum maximum power point voltage for the combined array.

boB

[jimbo]

Won't be as good as if all the PV is pointing towards
the sun, but it will work best that it can

Yes but if i have them all North to get the most i would need another classic and would also have my batteries start discharging earlier.  With the 4 panels facing NW my batteries stay on float all the way until sunset where as before power would be minimal 1.5hrs before that.  Panels are cheap!!