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Small Cabin Forum / Off-Grid Living / Solar panel Output Question
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groingo
Member
# Posted: 5 Nov 2014 10:04
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OK, I am showing power output of 20 volts which should give me (in round numbers) 5 amps per panel or 20 amps to work with yet my latest charge controller with batteries at 12.20 or 60% is only showing an input charge of 1.2 to 2 amps tops....needless to say the batteries are not getting charged....I have this bad feeling and unfortunately the generator is back to work.

cman47c
Member
# Posted: 5 Nov 2014 13:45
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You do not say what your solar panel wattage is. This will determine how many charging amps you have. I assume you must have 60-100 Watt panels if you are expecting 5 amps per panel. The max amps are also only developed under max sun, so if the panels are shaded the amps will be less. The batteries will get charged at 1.2-2 amps, only slower, OK unless there is constant load on them.

MtnDon
Member
# Posted: 5 Nov 2014 14:41 - Edited by: MtnDon
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Do you have a clamp meter? One that works on DC?

If you do try bypassing the CC for a test and measure the amps and volts at the batteries under bright noon day sun. That will eliminate the PV panels as being the source of the perceived deficiency. One panel at a time would also eliminate there being any one panel with a problem.

I'm assuming there have been no changes that were made to the system. Rather, the output has simply dropped and the weather is approx the same and the batteries are truly in a partial state of discharge.

groingo
Member
# Posted: 5 Nov 2014 15:36 - Edited by: groingo
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Ok Don:
I tested the individual panels and they averaged 20 volts each at just a hair over 5 amps each.
I have measured prior and gotten a bit higher readings in full sun of 22 volts, mid 5 amps.

Measured at the batteries using charge controller I have input to the controller from the panels of 12.57 with 1.3 amps going to the batteries and batteries are 12.20 with nothing connected.

MtnDon
Member
# Posted: 5 Nov 2014 16:11 - Edited by: MtnDon
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sounds an issue with the CC



groingo
Member
# Posted: 5 Nov 2014 17:53
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Don:
Me too, so am waiting to hear back from Midnite to see if the charge parameters can be changed (within reason) on their charge controllers, the video I watched seem to indicate they could which would be helpful.

creeky
Member
# Posted: 5 Nov 2014 18:17
Reply 


If I could ask a few questions.

So you have input from the controller to the batteries at 12.57. With 1.3 amps. Is this panel or are the panels in full sun? Part cloud. Is there any shading at all on the panels at this point?

The controller will not show the panel voltage. It will show the voltage it has got the batteries up to. So if you're seeing 12.6, your batteries are charging (they were 12.2). They will continue to rise the longer the day goes on. Assuming there is sun.

They should take your batteries to something like 14.5 which will allow the batteries to charge fully.

Once the sun has gone down you'll see the battery voltage drop.

By way of example. This morning my batteries read at 12.5. After the sun came out they slowly, over 4 hours, rose to 15.1. They stayed at 15.1 for three hours. They were then fully charged and the voltage dropped to "float". Around 13.8.

The reason the charge/float voltage is so high is the temperature compensation is in operation and the batteries are cool.

Now that the sun has been down for over an hour while I made supper and lights are on, fridge is running, tv and internet on ... my batteries read 12.63.

Might I suggest double checking that your charging parameters are correctly set and then be patient. It can take many hours for solar to fully charge the batteries.

Heck, who cares how long it takes. Now that you have the system the charge is free.

MtnDon
Member
# Posted: 5 Nov 2014 18:19
Reply 


Like on a Kid? There are fully user adjustable set points for the bulk to absorb change. The absorb time is user programmable and the float voltage is user programmable. Add a Whixbang Jr and you get some nice in-out data collection too.

MtnDon
Member
# Posted: 5 Nov 2014 18:26
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Quoting: groingo
panels of 12.57 with 1.3 amps going to the batteries


I think that is a key piece of info, assuming the sun was still shining about the same as it has in the past. High noon and no clouds I always see near maximum panel rated power IF the batteries are low and the charger is in BULK. Does that charger indicate the mode it is in? The Kid does. IF the charger had switched to Absorb you can't expect max amps.

IF the battery at rest voltage is down and the sun is bright the amps should be much higher when you have 4 panels in parallel like that.

groingo
Member
# Posted: 5 Nov 2014 19:16
Reply 


This controller I have been using has been a bit of a mystery as it shipped with two key features missing, the ability to display Panel Voltage and Panel Amps, even say so in the manual but for some reason they are missing and I am suspecting some other issues as well.
At this time I just finished a generator recharge of the batteries so they are full to the top and beyond yet the gauge shows only 3/4 full while the battery voltage displays correctly at 12.97 where 12.60 is actually full so there looks like a hardware problem, will be switching back to controller number one shortly and keep an eye on it and see what happens.

groingo
Member
# Posted: 6 Nov 2014 14:33
Reply 


Will be getting a new KID controller after speaking with Roy at Midnite, he verified the features I was looking for and much more, and he too is like me, all the information and manuals are right where they should be, next to the toilet!

MtnDon
Member
# Posted: 6 Nov 2014 22:31 - Edited by: MtnDon
Reply 


You might want to think about placing the panels in two series strings and then those in parallel. With the distance from PV to CC that should reduce voltage drop. I can also help with a little more gain when the sun is at bad angles like early and late in the day. Countering that is a slight reduction in CC efficiency, from having to drop from a higher voltage. It might be worth considering; at least do theoretical calculations on the difference in voltage drop.

groingo
Member
# Posted: 7 Nov 2014 09:02
Reply 


Don:
Oddly one thing I haven't had much of is power loss from panels to controller which when I do a static no load test shows a 1.5% loss from end to end on the power cable.
My roadblock does not appear so much to be lack of power but getting the controller to use more of what is available and put it into the batteries, I have very timid charge controllers....they need to be more aggressive and this is what I hope the KID will allow me to provide.

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