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JiminDenver's avatar
JiminDenver
Explorer II
Apr 04, 2015

Much happier now

When I was running the air conditioner test using the 245w mono and 250w the numbers were the opposite of what I expected based on what I had seen with the Schott poly 230w. Today I put one of the panels out for a nice long day in float and when I checked what I thought was it's controller, it was asleep. I had ID'd the controllers backwards and it makes sense now.

The 250w poly, which is the same physical size as the 245w mono, constantly produced a good half of amp more. It was hitting 17.75a here in Denver and should cross 18 amp at altitude. The 245w mono peaks at just over 17a but usually runs high 16s.

They both had a 35v Voc that morning but when I took Vmp in bright sun light, the poly was running at 33v, the mono at 26v. When the light dropped some and the panels were not facing the sun so much, the poly dropped to 26v Vmp, the mono to 20v. It was obvious the poly was going to keep it's voltage up longer in lower light than the mono. Like the Schott, the poly is producing enough to wake the controller at first light.

I hope to run more test in various conditions but considering the panels have the same foot print and only 5 watts difference between them, I'd say the hype over mono's being more efficient is bull in bright light or low.
  • BFL13's avatar
    BFL13
    Explorer II
    Apr 04, 2015
    If they are the same physical size then in theory, the mono (being more efficient than poly) should have more watts than the poly.
  • JiminDenver's avatar
    JiminDenver
    Explorer II
    Apr 04, 2015
    While shopping for panels I noticed thet you din't see a difference in foot print until the mono was a 275 watt vs a 280w poly. At that point the poly went to a 6 foot panel and much higher Voc.
  • JiminDenver's avatar
    JiminDenver
    Explorer II
    Apr 05, 2015
    At one time polys were bigger. My 230w poly is slightly bigger than my 245w mono and considerably bigger than the 220w mono. The trade off for a smaller footprint was less low light abilities.

    A while back I remember reading that poly tech was still advancing and it seems footprint wise it has caught up with mono. I'm still waiting for the light cloudy conditions that will knock the mono down to a few amps to see how the new polys will do but so far they seem to have the other low light characteristics of the 230w poly so I'm hopeful.
  • westend's avatar
    westend
    Explorer
    Apr 05, 2015
    Jim,
    I hope you have time to post up a test including the air conditioner. It is an addition that I need to make, also.
  • JiminDenver's avatar
    JiminDenver
    Explorer II
    Apr 05, 2015
    West

    These numbers came from the two panels and running the 5000 BTU air conditioner for four hours. I feel the three 250w panels flat will handle it mid day when we are likely to need it the most. I was going to window mount it but instead have decided to put it in the rear storage under the bunk, just open the storage door for ventilation while running.

    AC on solar test
  • westend's avatar
    westend
    Explorer
    Apr 05, 2015
    JiminDenver wrote:
    West

    These numbers came from the two panels and running the 5000 BTU air conditioner for four hours. I feel the three 250w panels flat will handle it mid day when we are likely to need it the most. I was going to window mount it but instead have decided to put it in the rear storage under the bunk, just open the storage door for ventilation while running.

    AC on solar test
    Thanks, Jim, I hadn't seen your posts there. I have a few ideas about mounting the AC, too. I'd use a window but all my new residential sliders are about two inches too small. It may go in the back, mounted up at the ceiling.

    Have you had a chance to sun the AC on a warm day? Did the 5000 BTU unit keep the temps down inside? I'm just curious more than anything, my rig is built like a big foam cooler so I think a 5000 BTU unit will work well.
  • JiminDenver's avatar
    JiminDenver
    Explorer II
    Apr 05, 2015
    West

    It hasn't been warm enough to really test it in the trailer yet. In our case it's purpose isn't to cool a 100 degree rig down in high humidity, but rather start it when it is still cooler and allow it to keep the temperatures down as the day heats up.

    Size wise the unit is rated for 150 sq ft and our trailer has 187. Luckily I can even it up by closing off the bunks, bathroom and even the bedroom if it gets hot enough. I spent a year figuring out which window shaker used the least power, after seeing it run I now know I could have gone up to a 6000 BTU energy star model.

    The only way I can get ours up to the ceiling where is would be most effective would be to box it and butt it up against the window in the upper bunk. I was going to hang it out one of the emergency exit windows but I worry about the frame handling the weight. Under the bunks is least effective but out of the way, easy to use and will look better.

    Last thing is if you are not worried about running it directly off the solar, a none energy star unit is half the price, lighter and doesn't use that much more power than mine. (50w if I remember right)

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