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Post by ricksctc on Sept 15, 2017 17:06:32 GMT -8
Hi, I have 2x100 12v, with a Wanderer PWM controller connected to a 105ah AGM battery. Seems to be working ok but I want to check the actual outputs of the panels. Do I need to disconnect the PV leads from the controller to get an accurate measurement? Given that it's a parallel system how do I figure each panel output if the parallel output is less than 2x the rated voltage and amperage of each panel?
These are mounted and on a trailer roof.
Another point is that I store this trailer in my garage and plan on rolling it out into the sunshine one day or so a week. There won't be any load on it. Any problems with recharging that way?
Thanks,
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Post by rabird on Sept 16, 2017 3:38:42 GMT -8
you can test the combined panels output at the controller. You need to know how to use a volt/amp meter!!!
disconnect the panels at the controller and probe each wire with the meter set for volts, ~20v is what you should get, not 2 x volts, this is Voc. With the meter set to amps you do the same to measure Ioc. This should be 10A or so, you'll need a meter that exceeds 10A. It is easy to blow the internal fuse in the meter so be sure the meter is set to measure more than 10A and the probe are set to measure amps.
^^^ that just test that the panels work. Once connected to the battery the panel voltage should match the batt voltage when batt voltage is rising and will far exceed batt voltage when the controller is tapering power into the battery.
Actual charging output. A clamp around amp meter lets ya do that without disconnecting anything. Simply use it to measure the amps going into the battery. You can also monitor battery voltage. The controller allows the battery voltage to rise to mid 14v, hold it there for 2 hrs and then let it drop to float of 13.? and hold it there. During the time that batt voltage is rising you can measure amps, it should be the full amount the panels makes in that amount of son, that angle to the sun, while the batt voltage is held at 14+v the amps taper by the controller.
A full sunny day a month in the sun ought to be enough to maintain the battery.
without a amp meter (or knowing how to use one), I'd monitor batt voltage hourly, watch it rise to the set pt of 14.?, what it stay there for 2 hrs, watch is fall to float of 13.?.
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Post by ricksctc on Sept 16, 2017 8:40:34 GMT -8
Thanks for the feedback. I know I'm 12v out, I didn't catch the error in my post. I've got it in normal charge now, according to the Wander manual, and I'll leave out until float charge. Measure the battery voltage tonight and tomorrow I'll disconnect the panels from the controller and meter the output. I'll get a DC amp meter from a friend.
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Post by Jimmy on Oct 23, 2017 4:53:31 GMT -8
rabird
I want to better understand measuring my solar output. I installed a bayite DC 6.5 100 volt meter. Works great. Keeps a log of how many kw I have used. Shows volts and amps. This shows use only. I am interested in seeing what the panels are producing. I have 800 watts of 100 watt panels 24 volt battery bank. And I have another system for my rv of 200 watts 12 volts. I Have a small meter the size of 2 decks of cards. I put it on dc 200 on the volt side. When the sun is out I get a reading checking the pv terminals on the solar controller. The reading is 8.6 on the 8oo watt panels and 2.4 on the 200 watt panels. What does that mean? It cant be 8 volts coming from the panels.
What about the rj45 plug on the epsolar 40 amp mppt controller. Can I do anything with that?
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Post by rabird on Oct 23, 2017 8:08:41 GMT -8
check the meter!  graph from epsolar software PWM, panel and batt V same till abs then panel voltage rises, not really, the duty cycle is less than 100% so ya get an average of batt V and panel Voc based on the time it is on/off (average), this on/off happens faster than the meter can read! As current 'tapers' the off time is more, off time is Voc of 20v so the ave creeps up. 2hrs later float and less sun so array V is all over the place. |
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Post by Jimmy on Oct 23, 2017 8:35:13 GMT -8
Ok I am getting 28.3 on my battery the charge controller is blinking and I am getting between 15.9 and 16.3 on my voltage meter checking the pv terminals. The sun is not out. Are these readings normal? What do you use to get that chart? Are you reading it from a computer attached to the rj45 plug or what kind of a meter is it?
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Post by Jimmy on Oct 23, 2017 8:54:17 GMT -8
So your controller is pwm no mppt. Do you not value the difference?
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Post by rabird on Oct 23, 2017 10:11:24 GMT -8
your system is big enough to go MPPT, but when a 40A controller is $54 and has BT capability and the system is small I stick with PWM and spend the difference on more power! The controller has a LCD and a few buttons to scroll through panel V, batt V, amps ... PROGRAMABLE via the app! The graph was made in the software from epsolar via the telephone type jack to laptop, to give ya an idea of the power, here is another at the same time, years ago.  current from array matches current to battery PWM 12v. current went up with more sun then 'tapered' during abs to nill. Your voltages seem low for a series connection. But sun not out means nothing! Do you measure ~70v when the sun is out? 4 panels in series with Vmp of 17v = 68v 16v would be the input V for a single or parralled 12v panels. |
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Post by tattoo on Oct 23, 2017 11:54:31 GMT -8
Well Bird, I spent all day looking, reading and watching about solar since the weather is crappy here..... What I come to the conclusion is I could have ran up to 8 100w panels with my 40a CC with NO problems.... When you said I would burn up my 40a CC when I went from 4 100w panels to 5 100w panels you had me worried and second guessing myself but not anymore.... That's why I went up to a 60a CC for 8 100w panels... But I wanted another CC anyway....
Thanks for rainy stormy days...........
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