Off Grid System Verification - Please Help!

vtmaps

Re: Off Grid System Verification - Please Help!

SteveG wrote: »

Do you happen to know if any of this wiring would be included in a prewired E-Panel? By the name pre-wired, I assume that the wiring between the controller and the inverter is already done. However I assume the rest (array to controllers, controller to battery, battery to inverter) is not included and would need to be purchased. Is this correct?

You will need to supply array to combiner, combiner to Epanel, and battery to Epanel. There is a battery bus in the Epanel and connections from that bus to circuit breaker to controller and from that bus to circuit breaker to inverter are all internal to the Epanel. Look at Midnite's site. They have good wiring diagrams and even videos of how to hook up an Epanel.

--vtMaps

SteveG

Re: Off Grid System Verification - Please Help!

vtmaps wrote: »

You will need to supply array to combiner, combiner to Epanel, and battery to Epanel. There is a battery bus in the Epanel and connections from that bus to circuit breaker to controller and from that bus to circuit breaker to inverter are all internal to the Epanel. Look at Midnite's site. They have good wiring diagrams and even videos of how to hook up an Epanel.

--vtMaps

Thanks vtmaps :]

If I were to get a second Midnite controller over the Tristar MPPT that I originally mentioned, like you suggested, would you recommend the Midnite Classic 150 controller for the 3x3 Yingli panels? Cariboocoot already recommended the Midnite Classic 200 controller for the Lumos. Or would the Voc be high enough to go to another 200 controller?

vtmaps

Re: Off Grid System Verification - Please Help!

SteveG wrote: »

If I were to get a second Midnite controller over the Tristar MPPT that I originally mentioned, like you suggested, would you recommend the Midnite Classic 150 controller for the 3x3 Yingli panels? Cariboocoot already recommended the Midnite Classic 200 controller for the Lumos. Or would the Voc be high enough to go to another 200 controller?

I just looked at the OP:
( 18 ) Lumos Voc 44.8V, Isc 5.29A, Vmpp 36V, Impp 5A . There will be 9 strings of 2 each.
( 8 ) Yingli Voc 37.0V, Isc 8.54A, Vmpp 29.5V, Impp 7.97A. There will be 4 strings of 2 each.

The Yingli will not work in a 4x2 configuration (Vmp x 2 is not high enough). Now you want to go 3x3 with the Yingli. good. 3 x Voc= 111. That is below 150 volts, even with cold temp adjustment. The Midnite Classic 150 is a better choice. It can handle higher current than the classic 200.

Do you still want to go 9x2 with the Lumos? If so the Classic 150 is a better choice, for the same reasons. I believe that Vmp = 72 is high enough for a 48 volt system. Check out Midnite's online string sizing tool and see if they agree with my recommendations.

All Midnite chargers run more efficiently (and therefore cooler) when the input Vmp is not too much higher than the battery charging voltage (charging up to 62 volts for a 48 volt system). If the distance between the panels and the controllers is very large sometimes it makes sense to put more panels in series to raise the Vmp which allows for a thinner (=cheaper) cable. The price you pay for a thinner cable is higher Vmp and Voc, which means you may need a classic 200 or 250 and they will run less efficiently because of the higher Vmp.

--vtMaps

SteveG

Re: Off Grid System Verification - Please Help!

vtmaps wrote: »

I just looked at the OP:
( 18 ) Lumos Voc 44.8V, Isc 5.29A, Vmpp 36V, Impp 5A . There will be 9 strings of 2 each.
( 8 ) Yingli Voc 37.0V, Isc 8.54A, Vmpp 29.5V, Impp 7.97A. There will be 4 strings of 2 each.

The Yingli will not work in a 4x2 configuration (Vmp x 2 is not high enough). Now you want to go 3x3 with the Yingli. good. 3 x Voc= 111. That is below 150 volts, even with cold temp adjustment. The Midnite Classic 150 is a better choice. It can handle higher current than the classic 200.

Do you still want to go 9x2 with the Lumos? If so the Classic 150 is a better choice, for the same reasons. I believe that Vmp = 72 is high enough for a 48 volt system. Check out Midnite's online string sizing tool and see if they agree with my recommendations.

All Midnite chargers run more efficiently (and therefore cooler) when the input Vmp is not too much higher than the battery charging voltage (charging up to 62 volts for a 48 volt system). If the distance between the panels and the controllers is very large sometimes it makes sense to put more panels in series to raise the Vmp which allows for a thinner (=cheaper) cable. The price you pay for a thinner cable is higher Vmp and Voc, which means you may need a classic 200 or 250 and they will run less efficiently because of the higher Vmp.

--vtMaps

I'm thinking of going in a 3x3 configuration with the Yingli, correct. This would enable me to run 6 AWG wire from the combiner box to the controller (100' run for both arrays).

For the Lumos, I was thinking of going 6x3, in order to also run 6 AWG wire. This would mean a Midnite 200 controller from what I understand. If I can run 6 AWG in the 9x2 configuration 100' with minimal loss, I would rather do the 9x2 configuration to have identical charge controllers (Midnite 150). So would I need to go 6x3 for the 6 AWG wire, or would 9x2 also work?

vtmaps

Re: Off Grid System Verification - Please Help!

SteveG wrote: »

I'm thinking of going in a 3x3 configuration with the Yingli, correct. This would enable me to run 6 AWG wire from the combiner box to the controller (100' run for both arrays).

For the Lumos, I was thinking of going 6x3, in order to also run 6 AWG wire. This would mean a Midnite 200 controller from what I understand. If I can run 6 AWG in the 9x2 configuration 100' with minimal loss, I would rather do the 9x2 configuration to have identical charge controllers (Midnite 150). So would I need to go 6x3 for the 6 AWG wire, or would 9x2 also work?

For the Yingli 3x3, at full power, you will have a voltage drop of 1.93 volts in the 6 AWG cable and 46.4 watts will be dissipated in that wire.
For the Lumos 6x3, at full power, you will have a voltage drop of 2.42 volts in the 6 AWG cable and 72.5 watts will be dissipated in that wire.
For the Lumos 9x2, at full power, you will have a voltage drop of 3.63 volts in the 6 AWG cable and 163.2 watts will be dissipated in that wire.

I think that the Lumos 9x2 would not be a good choice with that much voltage drop. Its Vmp of 72 is just barely enough for a 48 volt system. The downside to raising the Vmp to 108 is reduced efficiency of the controller. To see what the trade off looks like look at the numbers for my impending system expansion: http://forum.solar-electric.com/showthread.php?15907

--vtMaps