24v or 36v

firehallman Registered Users, Users Awaiting Email Confirmation Posts: 1
hey all! im just getting into solar and just got some cheap new panels that were never used/barn find.
canadian solar CS6P-235M 
link:  http://www.solardesigntool.com/components/module-panel-solar/Canadian-Solar-Inc./796/CS6P-235M/specification-data-sheet.html
imp 7.82a
vmp 30.1v  voc 37.2v 
whats the voltage 24v or 36v?


  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Those panels (single) will barely charge a 24V battery in cool weather and are not likely able to EQ
    Only use with PWM controller.

    If you series connect them (74.4Voc), 60.2Vmp, you could use with a MPPT controller for 24v battery.  3 in series would work for a 48V battery.

    There is not much 36V solar gear around, I would not consider it as an option at all.

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,406 admin
    There are two major types of solar charge controllers... PWM (pulse width modulation) and MPPT (maximum power point tracking).

    PWM controllers require specific voltage solar panels for optimum charging of a battery bank... Vmp~18 volts for a 12 volt battery bank, Vmp~36 volts for a 24 volt battery bank, and Vmp~72 volts for a 48 volt battery bank...

    MPPT controllers are more sophisticated (& more expensive) and can take a wide range of solar array voltages and "down convert" to a lower voltage/higher current battery voltage... More or less, you need Vmp>24 volts for a 12 volt bank; Vmp>48 volts for a 24 volt battery bank, etc.)... The maximum voltage depends on the brand/model of MPPT charge controller.

    Details matter here... Generally we suggest you define your loads (battery voltage, Amps/Watts of power, AH/WH of energy used per day, etc.) to start a system design. The idea is to have a "balanced" system. Loads > battery bank > solar array... Your loads and hours of sun per day (location, array tilt) aslo define your solar array.

    There are lots of details needed to design and build a solar power system. And while your solar panels do not "match" any standard battery bank, you can use a PWM controller on a 12 volt bank (you will only get ~1/2 the rated power of the panels). Or you can use the panels and a more expensive MPPT controller.

    So--Tell us about your loads. How many panels. Where the system will be installed. And how you want to use the system (learn, weekend cabin, running loads 9+ months a year, etc.).

    Solar power is not cheap. Batteries have to be replaced every 3-5 years (if using "golf cart" type deep cycle batteries), etc... Generally, you want the least amount of loads and most efficient devices (l.e., LED lighting vs filament, tablet or small laptop vs desktop computer, etc.)....

    You need good access to the sun--Branches, trees, buildings, overhead power line shadows, etc. are all bad news for solar. Assuming you are towards the north (Kitchener Ontario?), your winter sun is probably not great...

    http://www.solarelectricityhandbook.com/solar-irradiance.html (down right now?)
    https://pvwatts.nrel.gov/pvwatts.php (a bit more complicated)

    For a 1,000 Watt array, tilted to 45 degrees for Kitchener ON
    MonthSolar Radiation
    ( kWh / m2 / day )
    DC Energy
    ( kWh )
    ( $ )

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Photowhit
    Photowhit Solar Expert Posts: 6,001 ✭✭✭✭✭
    At least 1 seller use to call those 20 volt panels. They really aren't high enough voltage to reliably charge a 24 volt battery bank. Tell us more about what your plans are and what budget... 

    Don't worry, we're a pretty thrifty lot and will just offer suggestions.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.