Very close to max wattage on my Classic 200

Wbuffetjr1Wbuffetjr1 Registered Users Posts: 51 ✭✭
Just installed my system this past Summer. I have 9 Solarworld 345 watt panels connected in 3 strings of 3 for a total of 3,105 watts. I have a Classic 200 charging a 48V battery bank. The "max allowable wattage" on the Classic 200 is 4,080 watts. So far, I have seen a high power of 4,024 watts produced in the logs. If this thing happens to get up to say 4,100 watts can it damage my charge controller or will the Classic protect itself by limiting the power??  

Comments

  • mcgivormcgivor Registered Users Posts: 1,278 ✭✭✭✭
    Probably not, a quality company would have conservative maximums, Midnight is a quality company, so the maximum wattage seen would probably  be a transient high and safeguards are more than likely incorporated, Midnight users please comment.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • HorseflyHorsefly Registered Users Posts: 258 ✭✭✭
    edited October 17 #3
    Chad - It looks to me that the Classic 200 limits its output current to 79A, according to the spec. Even if your PV array may be capable to produce more power than would translate to 79A, it will only produce what the CC pulls. The Classic will limit what it converts for your batteries, so there really isn't anything you can do to damage it with "too much power". At least not if you 3 x Voc can't ever get above the 200V limit of the Classic 200.

    Steve
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • EstragonEstragon Registered Users Posts: 1,543 ✭✭✭✭
    Going a little over 200v on a classic200 is okay. From 200 to 248v it stops charging, but lives on to charge when the voltage drops without letting the magic smoke out.

    As others mentioned, the classic won't normally draw more than rated even with more panel. To a point, extra panel is a good thing for lightly overcast days. Like pretty much any electronics though, running it at full rated output for long periods can make them hot internally and shorten lifespan.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭
    Estragon said:
    Going a little over 200v on a classic200 is okay. From 200 to 248v it stops charging, but lives on to charge when the voltage drops without letting the magic smoke out. 
    To add to what Estragon is saying the VOC is in danger of dropping into the Hyper VOC range for the Midnite classic, it's usually in the early morning when the panels are cold. Once the sun warms them the VOC will drop. So the time you are in the "Hyper VOC" range is when the panels aren't very productive so little to no loss!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • Wbuffetjr1Wbuffetjr1 Registered Users Posts: 51 ✭✭
    Thanks everyone!

    I am still slightly confused.  I just don't see how to predict what these panels are going to do at this altitude. The Classic sizing tool for the 200 says my system is good for hyper VOC down to -93C.  However, I am assuming that number isn't going to be the same for me at 10,000'.  Surely I will still have plenty of cushion, but is there anyway to calculate a more correct number? 

    Bottom line is I don't want to damage anything this Winter when there is no easy way to get up there regularly to keep an eye on the system. 
  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭
    We might be able to call on the All mighty @boB ! To give some insight, but I think you're fine.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭
    I guess I should explain, boB is boB Gudgel who diesgned the Classic and is a forum member here.

    They also have their own forum at;
    http://midniteftp.com/forum/index.php
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • BB.BB. Super Moderators Posts: 26,837 admin
    Voc-cold is NOT the result of sun (any sun, from weak morning sun to full noon-time sun) is the same... It is the temperature of the cell... Usually, the worst case is morning sun on a cold panel/solar cell (note that radiative cooling can bring cell temperatures down further--Like frost can form on an open field even if ambient temperatures are above freezing). Once you get "normal" sun on the panel, the cells generally are generally above ambient temperatures.

    Any sort of loading will bring down Voc (voltage open circuit) voltages towards Vmp (voltage maximum power) or lower... But we want to be sure that your system will not "self destruct" under normal conditions. And that you do not have to pull the fuses/open the array breakers on frosty mornings to protect the charge controllers.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 1,543 ✭✭✭✭
    To give you a sense of winter sun can do to panel temps, last Jan I during a cabin visit I cleared the snow off the arrays. The bottom layer was the sort of wet sticky stuff that falls early in winter, and by Jan it was pretty crusty and stuck on. A fair bit was still stuck on, but I got about 50% clear.

    Even at -25°c and with a bit of a breeze, it took less than an hour for the rest to melt.

    At altitude, I suspect you could see better current in thinner, dry air, but not higher voltage vs sea level at equal ambient temps.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • boBboB Solar Expert Posts: 941 ✭✭✭
    edited October 17 #11
    10,000 feet, eh ?  The modules should put out a bit more up that high.  Less air for cooling too.  I know that Classics have been operating up at that high of altitude but I haven't been to any of those installations so I'm not sure what to expect.

    Maybe just try it and report back ?  The Classic may limit itself, current-wise.  If it does limit the current, it does this by raising the input voltage and so the Classic MAY get a bit hotter.

    boB
  • Wbuffetjr1Wbuffetjr1 Registered Users Posts: 51 ✭✭
    Thanks again for all the insight.  I will have a load on the system every day throughout the winter.  I will be running a 1/3hp electric motor on a timer for 10 hours every day. Timer kicks on a couple hours before sunrise. If I am hearing BB correctly, that will help keep things reigned in. I would think any extra heat in the room from the classic would be welcome up there through the Winter. 

    boB - I can definitely report back. I am new to solar and the classic so I cannot remember, do the logs show max amps also? Is that all I would be looking for? 

    Thanks everyone! 
  • BB.BB. Super Moderators Posts: 26,837 admin
    Voc is, in some ways, a theoretical figure. Any loads on the panel can lower the voltage (a bit)... However, since we have no control over the how the charge controller operates (sweeping current for MPPT function, "restarting" at the sun rises, etc.).

    I would suggest that you do not push the limits.

    HOWEVER, Midnite for (most?) of their controllers has a high voltage safety mode. Basically, if the array hits maximum input voltage, the controller shuts down and protects itself to (for example) 150VDC+Battery Voltage. HyperVOC:

    http://midnitesolar.com/pdfs/whyHyperVOC.pdf

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Wbuffetjr1Wbuffetjr1 Registered Users Posts: 51 ✭✭
    Bill, I hear you and I was actually trying NOT to push the limits. I knew the panels would produce a little more than the rated wattage, but I had no idea it could be 30% more! Now I find myself pushing the limits and I am not sure what to do. 

    I suppose as long as the controller shuts down to protect itself then I will be ok.  Although I am sure putting the controller through that regularly can't be good for longevity.   
  • BB.BB. Super Moderators Posts: 26,837 admin
    edited October 19 #15
    In terms of output wattage... It is Vmp*Imp... Cold panels, Vmp rises and does support higher output power for an MPPT type charge controller.

    In general, good quality MPPT controllers will limit their output current to rated levels--Safely and reliably.

    However, obviously, the more energy you pump through the charge controller, the more heat that is generated. Midnite controllers (and others) will reduce power throughput if the controller temperatures rise above programmed limits.

    And, at 10,000 feet, the air is much thinner and most electronics/motors/etc. should be derated to because of the lack of ability of of high altitude air to carry heat away.

    If you want to get full performance of the solar array--You may need to split it (say in 1/2) and run two charge controllers in parallel to charge the one battery bank (that is perfectly OK).

    Or, possibly other design changes (Classic 150's have lower input voltage, but higher output current ratings). You are already at 48 VDC battery bank--So you cannot go to a next "higher standard voltage" battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 1,543 ✭✭✭✭
    Splitting the array with a second classic also has the advantage of some redundancy for when a controller fails.

    If you do stay with the single classic, you might want to inspect it regularly to make sure vents don't get blocked. I haven't had a problem yet, but I have to think a warm classic might make a nice nesting place for a critter.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Sign In or Register to comment.