4kw new off grid system

[Ionelissy]

Hi everyone,

I have just installed 16x 250w panels, total of 4kw

1x Outback Flexmax 80 amp CC

12x 230ah 12v batteries wired in parallel, total 2760 amp @ 12v

1x 3000w inverter @ 12v

Fow now I am forced to use the system at 12v because I only have the 12v inverter, but I plan on getting the 48v inverter to benefit from all 16 panels which can all be handled by the CC @ 48v (CC max watts at 48v is 6000w acording to the manual and max 1250w @12v)


CC max voc is 150v, each panel has a 37v voc and 30v vmp......now I use 6 panels in parallel to get the max 80 amps at peak (with 5 panels in parallel I only get 70-72 amps at peak)

my question with the 12v system I use now: can I wire more than 6 panels in parallel to get the 80 amps even in early mornings and late afternoons? ..voc and vmp will remain unchanged.


thanks.

[Sunking]

12x 230ah 12v batteries wired in parallel, total 2760 amp @ 12v

That was a huge mistake that will cost you dearly in about a year when you end up replacing the batteries. When that time comes buy yourself some 4 or 6 volt batteries @ 800 AH.

[Ionelissy]

That was a huge mistake that will cost you dearly in about a year when you end up replacing the batteries. When that time comes buy yourself some 4 or 6 volt batteries @ 800 AH.

thanks for that, I will get the 48v inverter in a month ....

how about answering my question?

[Sunking]

If I remember correct the max power input for the FM 80 operating @ 12 volts is 1200 watts or 1250 watts. Check the manual.

But you might have a huge problem on your hands. With 5 panels only leaves you the option of wiring them only in parallel which means the Imp panel current is up around 45 amps. What size wire is used from the panels to controller, and what gauge is it? Minimum required is # 8 AWG but if the 1-way distance is more than 5 feet would mean significant losses and would explain why you are not getting the current you are expecting.

You might try the panels in a 2 x 3 config to get the current down to 22 amps and cut the losses 50%. But again I cannot tell if what you have is adequate or not by not knowing the gauge and distance.

[inetdog]

If I remember correct the max power input for the FM 80 operating @ 12 volts is 1200 watts or 1250 watts. Check the manual.

But you might have a huge problem on your hands. With 5 panels only leaves you the option of wiring them only in parallel which means the Imp panel current is up around 45 amps. What size wire is used from the panels to controller, and what gauge is it? Minimum required is # 8 AWG but if the 1-way distance is more than 5 feet would mean significant losses and would explain why you are not getting the current you are expecting.

You might try the panels in a 2 x 3 config to get the current down to 22 amps and cut the losses 50%. But again I cannot tell if what you have is adequate or not by not knowing the gauge and distance.

The reason this depends on your CC is that some CCs will limit the amount of input power they take from the panels and so can be used with oversized panel arrays. This lets them use the full output from the panels during off-peak sun hours but will not try to accept more than their input rating during peak hours when the panels will potentially generate power above the CCs input limit. Other CCs expect the panel maximum output to be kept below their input power limit. The design limits on the CCs ability to tolerate overpowered solar arrays varies from manufacturer to manufacturer and model to model.
They all, however, set a maximum voltage limit which has to be respected on cold as well as hot days. This puts a limit on how many panels you can put in series.

[Ionelissy]

If I remember correct the max power input for the FM 80 operating @ 12 volts is 1200 watts or 1250 watts. Check the manual.

But you might have a huge problem on your hands. With 5 panels only leaves you the option of wiring them only in parallel which means the Imp panel current is up around 45 amps. What size wire is used from the panels to controller, and what gauge is it? Minimum required is # 8 AWG but if the 1-way distance is more than 5 feet would mean significant losses and would explain why you are not getting the current you are expecting.

You might try the panels in a 2 x 3 config to get the current down to 22 amps and cut the losses 50%. But again I cannot tell if what you have is adequate or not by not knowing the gauge and distance.

I have 10 meters distance from the panels to the CC and solar cable size is 16 sq.mm which supports 4-10kw.

thanks.

[Ionelissy]

The reason this depends on your CC is that some CCs will limit the amount of input power they take from the panels and so can be used with oversized panel arrays. This lets them use the full output from the panels during off-peak sun hours but will not try to accept more than their input rating during peak hours when the panels will potentially generate power above the CCs input limit. Other CCs expect the panel maximum output to be kept below their input power limit. The design limits on the CCs ability to tolerate overpowered solar arrays varies from manufacturer to manufacturer and model to model.
They all, however, set a maximum voltage limit which has to be respected on cold as well as hot days. This puts a limit on how many panels you can put in series.

I tried 8 panels in parallel and of course voc and vmp stays the same even if I connect all 16 panels in parallel.... the CC does not have to limit anything, because wiring in parallel does not increase vmp and voc, it increases only watts.... which is what I need for off-peak hours, the only limit CC does it the output amps to 80.

thanks.

[Mike90250]

No matter how many more panels you add, you are limited to 80amps. If you stay at 12V, no need to add more panels. When you re-wire to a 48V battery bank, then you can add up to 4,000 watts of panels.

Your battery strings should be wired on the diagonal, like this article describes

http://www.smartgauge.co.uk/batt_con.html

[Sunking]

I have 10 meters distance from the panels to the CC and solar cable size is 16 sq.mm

Right there is your problem. You are taking a 7% voltage loss when you need to be at 2% or less. You can cut your losses by 75% by reconfiguring your panels 2 x 3. That will bring the loss down to 1.5%

[Ionelissy]

finally got my 48v inverter... set all my batteries @ 48v and now I have a 690ah battery bank charged by the 80 amp mppt Outback controller ...from the 4kw of LG solar panels.

So far, got a max of 3055w/55amps charging at peak... but measuring the sun I got only 807w/mp ... so everything is OK!


thank you all.

[sk_gc]

96v instead of 48v on array side?

Glad that you got it right.

Just speculating;

Why not 96v on array side and 48v on battery side? that you are using MPPT 80 amps CC.

Requesting experts here to suggest.

[Ionelissy]

Glad that you got it right.

Just speculating;

Why not 96v on array side and 48v on battery side? that you are using MPPT 80 amps CC.

Requesting experts here to suggest.

I actually have the array set in series of 4 panels, giving me a total of 120 volts.