Just a question on the CBI din rail midnight solar breakers, on the front it's listed as 150 VDC but on the side it's marked 125VDC? I am using the midnight string sizing tool for my #4 Array, and I am trying to decide between 3 to a series string or 2 to a series string
This is what I have. 260 watt Renesola panels, VOC 37.6, VPM 30.5, ISC 8.95 IMP 8.53 Lowest temp 5 F. Highest temp 95 F . The midnight sizing tool indicated a cold Voc of 127.8 volts, I'm just wondering about these breakers?
Quote from: Silvertop on September 23, 2013, 12:21:19 AM
I am trying to decide between 3 to a series string or 2 to a series string
This is what I have. 260 watt Renesola panels, VOC 37.6, VPM 30.5, ISC 8.95 IMP 8.53 Lowest temp 5 F. Highest temp 95 F .
Hi Silvertop.... I suppose you're the silvertop at NAWS with an induction cooker. Sorry I don't know the answer to your question about the circuit breaker, but I do know that your Classic will run cooler and more efficiently if you put those panels 2 to a series string.
Of course, if your panels are very far from the classic, you may want to increase the voltage to reduce line loss. But often when you raise the panel Vmp to reduce the line loss, you just trade reduced line loss for increased controller loss.
--vtMaps
This is kind of what I was thinking, but I still would like to find out about the 150vdc/125vdc din breaker. I also was wondering if I was wiring more than needed ( 2 to a string ). I have also heard about down converting losses so I'm leaning toward the 2 to a string anyway, but just wanted others opinions......
I tagged Ryan and boB on this they will answer your rating question, I am sure.
Tom
The breakers are listed by CBI to 125vdc we then had them listed to 150vdc. So if they carry the Midnite ETL sticker on them then they are rated for 150vdc.
Ryan
Is CBI just conservative ? Ryan what is your opinion on the down conversion losses? I do not need to run 3 to a string, it's not a long run. I just didn't want to over wire.......
Silvertop,
Know that I am NOT Ryan, but, forget your battery voltage. EDIT: (and since you appear to be considering 125/150 VDC PV breakers, ASSUME that the Classic in question is a Classic 150).
Further EDIT: Upon doing some sleuthing on the Wind-Sun site, appears that you are doing MN Combiners or e-Panels using the dreaded brand S CCs. Had thought that you were using the MN string sizer. [On a 48 V system, the Vmp/Voc of three PVs per string should not be a large problem, in fact strings of three will really be required, unless perhaps you are using Gel batteries ( the Vmp to two PV strings in warm/hot weather is really too low for a 48 V FLA battery)] ...
BUT, it appears that your battery bank is 24 V, so strings of two of the 60-cell PVs should be fine, and probably actually preferred ... end Further EDIT ...
You may have a Signature elsewhere, but have not looked. A Signature is your friend. My opinions -- on the 48 V systems here, use strings of three 60-cell PVs (like the PVs that you proposed in this Thread). Vic
Quote from: Silvertop on September 23, 2013, 12:28:40 PM
Is CBI just conservative ? Ryan what is your opinion on the down conversion losses? I do not need to run 3 to a string, it's not a long run. I just didn't want to over wire.......
That is just what CBI had them test and listed to.
We knew they would work at 150 VDC but had to go through the process (and expense) with ETL.
We did a similar thing at Outback Power way back when.
boB
Quote from: Vic on September 23, 2013, 01:43:25 PM
Silvertop,
Further EDIT: Upon doing some sleuthing on the Wind-Sun site, appears that you are doing MN Combiners or e-Panels using the dreaded brand S CCs. Had thought that you were using the MN string sizer. [On a 48 V system, the Vmp/Voc of three PVs per string should not be a large problem, in fact strings of three will really be required, unless perhaps you are using Gel batteries ( the Vmp to two PV strings in warm/hot weather is really too low for a 48 V FLA battery)] ...
BUT, it appears that your battery bank is 24 V, so strings of two of the 60-cell PVs should be fine, and probably actually preferred ... end Further EDIT ...
Yes my battery bank is 24 volt, thanks for all the input I'll give this up and go two to a string....