Thursday, 11 October 2012

For "Just Me"

I received the following welcome e-mail from Just Me 

Dani - thank you so much for sharing all of the details of your PV system in these two posts! If I'm not being too greedy, can I ask for one more photo of the display on your Outback charge controller - when the IN voltage is under 60 and the OUT voltage is still over 12. I know there are a lot of folks watching and learning from you. The MPPT controllers are generally much more efficient than the less expensive PWM charge controllers, but the differences lose a lot of folks in the math. That difference becomes really obvious when you look at panels connected in series for an MPPT controller versus panels connected in parallel for a PWM controller. When the panels are putting out less voltage than the battery level, a PWM controller will not charge the batteries at all but an MPPT controller will continue to put watts in the bank until the sum of the panel voltages drops below the battery level. This makes a HUGE difference on partly cloudy days and early morning and late evening. With your setup, you should still be drawing solar power into the batteries when each panel's individual output has dropped to 3V! Well done! 

Well, Just Me, here is the pic as requested...


This pic of our Outback charge
controller was taken at 7.00p.m. when
it was overcast and dark outside

Here is a close-up of the Outback charge controller screen:
We have also noticed is that even the moon and starlight generates volts - at 8.30p.m. last night 8.6 volts was incoming.

Just Me - thank you for your e-mail - I'm very grateful for the education.  Should the occasion arise in future, feel free to comment on my blog - that way everyone can learn from my mistake :)  But, I reckon it's just as well that RMan is in charge of the power generation...

12 comments:

  1. This is all so very interesting and exciting! Yes, thank you, Dani, for educating and inspiring us!

    ReplyDelete
    Replies
    1. Bee Girl - And "thank you" to Just Me for correcting information I posted :)

      Delete
  2. Dani,
    Thank you for posting this. We also use Outback, as it is a wonderful brand. We are not using the exact unit as you. We have a marine battery array which we charge with a diesel generator for a short period of time. It can charge for one hour and then provide emergency lighting and refrigeration and freezing for the entire day during an outage. We cook using small amounts of gas, and we have gas logs for emergency heat. Here in Virginia, cooling is usually more of an issue than heat. We use an Outback inverter unit which we think is superb.
    Thank you again for broadening our horizons.

    ReplyDelete
    Replies
    1. Jane - Outback is amazing in it's performance / information it provides.

      Such a pity that you couldn't get a solar panel to keep that battery charged for your power outages :)

      Yeah - here it's the heat issue too, but we have a short, but fierce, winter some years - this one being one of those... LOL

      Delete
  3. Thanks, Dani! I'm honored. Your close-up picture is a very cool thing to see. When the IN voltage is at 35.2V from 5 panels connected in series, that means each panel is putting out just slightly over 7V, but you're still able to put more watts into your battery bank at an output voltage of 12.5V. I imagine that the reason your controller is showing 0 watts output is that your battery bank was full at the time of the photo - that's a large part of what charge controllers do - keep your batteries from being damaged by overcharging.

    If your panels are able to output more watt-hours than you are using, you might consider setting up a second controller (inexpensive PWM model) as a diversion load controller. This could feed to a 12V water heater, a heating pad for your seedlings, or a spare battery from which other batteries can be kept on a trickle charge (e.g. for a lawnmower or tractor that is seldom used), or basically any other use that might be nice but not absolutely necessary. Power would be diverted to that load only when the main batteries are full and the solar panels are still able to put out more power.

    Yay, solar power! Thanks for sharing.

    ReplyDelete
    Replies
    1. Just Me - No, thank you - for showing me my error. I hate misleading anyone, and always welcome being corrected. I learnt something too LOL

      Nothing to beat "free" solar power - I'm loving it! The learning curve re: what to have on when, and for how long, and the "free-ness" of it all. Best of all, those in positions of power cannot flip a switch and leave me in darkness when the whim takes them... ;)

      Please - get your solar blog up and running - EVERYONE needs the information that you have to share. And, please, don't forget to let me have the link... :)

      Delete
  4. Thanks for sharing all the info. We are not ready for solar just yet, but I know when we are I will be referring back here.

    ReplyDelete
    Replies
    1. Garden Girl - If I've inspired you, even slightly, to consider ditching Escom and their price hikes / unreliable service and changing to solar power then I'm thrilled. All it takes is learning to use your solar power capacity wisely... :)

      Delete
  5. One reason solar panels are made to put out around 18 volts or more instead of 12.5 is so they will still charge batteries on cloudy days. The voltage will still be above 12.5 volts unless its extremely thick clouds and pretty dark. Problem is that the wattage is cut to 50% or less than what the panels will put out on a sunny day.

    I've had my best luck by facing 80 watts east toward the horizon and the same for west. All other panels are facing south or flat to catch the mid day sun. As soon as the sun rises the east facing panels start putting out near full voltage/wattage and when the sun is setting it does the same with the west facing panels. It works a little like tracking.

    ReplyDelete
    Replies
    1. David - We have our panels on our garage roof which faces due north, and they seem to be performing beyond our expectation. I understand about a panel or two the the east and west, but we have no secure place to place them - we have to be totally cognizant of the wind where we are - would hate to loose a panel loosely placed.

      Delete
  6. I just used my flexmax 60 for the very first time today Dani. It really impressed me how it kept charging late into the evening. Earlier on was'nt a very sunny day at all, but it still seemed to do pretty well. Really hope the sun is shining tomorrow so I can see what this baby is really made of.

    ReplyDelete
  7. FCH - LOL I can feel your excitement. Congrats on hooking up your solar power - there is nothing to beat it :)

    ReplyDelete

Thank you for taking the time to comment - it makes my day.

I have de-activated Word Verification, but if the spam floods back again, then I will be reactivating it.