A Forum run by Enthusiasts of MidNite Solar

General Category => System Design and Layout => Topic started by: Tobit on November 15, 2013, 02:55:52 PM

Title: MNPV3 Combiner + Classic 150/200 Charger, max. 100W Panels
Post by: Tobit on November 15, 2013, 02:55:52 PM
I really like the 100W panels I've been using, they ship for free to my difficult access property unlike larger panels.

If I have a MNPV3 Combiner, how many 100W panels (specs listed below) can I go with if using a Classic 150 or 200W charge controller?  I am really having a hard time figuring out the math.  Thanks.

Optimum Operating Voltage (Vmp)   18.9V
Optimum Operating Current (Imp)   5.29A
Open - Circuit Voltage (Voc)   22.5V
Short- Circuit Current (Isc)   5.75A
Maximum Series Fuse Rating   15A
Title: Re: MNPV3 Combiner + Classic 150/200 Charger, max. 100W Panels
Post by: Westbranch on November 15, 2013, 03:46:34 PM
Use the MN string calculator, you can play with array size etc...

http://www.midnitesolar.com/sizingTool/displaySizing.php
Title: Re: MNPV3 Combiner + Classic 150/200 Charger, max. 100W Panels
Post by: laszlo on November 15, 2013, 03:47:13 PM
Some more details about your system would be needed to do the calculations -- for example, what is your battery voltage, and the coldest recorded temperature in your location? Are you limited to only 3 PV combiner slots? 
Title: Re: MNPV3 Combiner + Classic 150/200 Charger, max. 100W Panels
Post by: Tobit on November 16, 2013, 06:55:10 AM
I will likely go with 24V battery bank.  Coldest temperature is around 0F.  I could go with a larger combiner but would rather not.
Title: Re: MNPV3 Combiner + Classic 150/200 Charger, max. 100W Panels
Post by: laszlo on November 16, 2013, 10:16:36 AM
With 24 Volts battery and Classic150,  you can series connect 5 of the above panels  in 3 strings with lots of comfort zone left both in terms of max amp (92A for 150) and max operating voltage (150Volts). You will need to use #4 wire from combiner to classic, and from classic to battery. It is possible to have 6 in series but IMO  it's not worth the stress and the unreliability it adds to the system. Code and best practices require overcurrent protection on the combiner output and the classic output -- so I would ause a Midnite mini-DC  with 4 breaker slots, or a Disco 6 slot,  so you can put a breaker for the output of the combiner in the same box.
Title: Re: MNPV3 Combiner + Classic 150/200 Charger, max. 100W Panels
Post by: Tobit on November 16, 2013, 12:39:29 PM
laszlo, thank you very much.  Ok, I think I will go with a 4x3 configuration.  It will produce much more than I need so I will have lots of fudge room.