How To Check Performance Of Installed Solar System On RV | The Forum has been moved to support.renogy.com

rouelf
Solar Newcomer

Posts: 4

How To Check Performance Of Installed Solar System On RV Oct 6, 2018 22:21:59 GMT

Post by rouelf on Oct 6, 2018 22:21:59 GMT

Pardon, it is kind of a long post:

I have 4, 100 Watt, total 400 Watts, Flexible Solar Panels from 3 Suppliers (Not Renogy) self installed on roof of my Motorhome. The 4 Solar Panel are installed in parallel to a Renogy MPPT Tracer 40 A Charge Controller. The Solar Panels are mounted with Eternabond Tape directly on the fiberglass roof. Six months and no issues with tape holding panels down on many, many freeway / highway trips.

Issue The surface coating of one the solar panels has degraded, shriveling, rough, kind of white, see photo below. To replace this, have purchased a Regony 100 Watt, 12 Volt, Flexible Monocrystaline Solar Panel. So, after receiving the Renogy solar panel, and before removing and replacing the obviously degrading solar panel, was wondering if there is a quick simple way to test / check the current solar system for performance.

For this time of the year, since the sun is not directly over head, have suspected that the performance of the installed solar system produces about 50% (200 Watts) of the 400 Watts from the 4 solar panels in parallel. But how to measure the output of the solar system.

I know and understand the proper procedure for testing / checking out individual solar panel for proper functioning. But if you have several panels connected for awhile, and later need to do a system checks, then the procedure though simple is tedious. Wonder if there is a less tedious process, like using a Watt Meter, DC Inline Power Analyzer, 45 A Continuous, 12 Gauge, with MC4 Solar Connectors, by Powerwerx, thru Amazon (happen to have one, purchased a while back, but never used). Though may be considered kind of pricy at ~ $54, but might be nice to have around for solar system usage during installation and overall system checks. Unless Renogy or …. has suggestions for easier solar system checking procedure.

Will try the following, with above Watt Meter in Place before the combined solar power input to the MPPT Charge Controller. All Solar Panels always connected in parallel:

1) In full sun, record all screen readings from the Power Meter.
2) Cover all Solar Panels with dark blankets, record all screen readings from the Power Meter.
3) Uncover one Solar panel to full sun, record all screen readings from the Power Meter.
4) Perform step 3 above for each Solar Panel, record all screen readings from the Power Meter for each Solar Panel, individually exposed to full sun.
5) Compare Power Meter readings to find underperforming Solar Panels.

This seems to work, below are my results. Though the offending degrading surface solar panel, is only about 16% underperforming compared to the 3 other Solar Panels.
That is not to bad yet, even though the surface of the panel looks terrible.
So I think I will use the new Regony 100 Watt, 12 Volt, Flexible Monocrystaline Solar Panel as a portable unit, for the time being, also to be connected in parallel.

Would appreciate any comments about this procedure, thanks.

	Power Watts	Current Amps	Voltage Volts
Full Sun All Panels	193.4	13.78	14.04
Rear Two Panels Only Full Sun	104.6	7.82	13.38
#1 Rear Panel Only	53.5	4.14	12.94
#2 Rear Panel Only	56.5	4.35	13
All Panels Covered	3.8	0.31	12.39
#1 Front Panel Only	54.8	4.24	12.93
#2 Front Panel Only	45.7	3.56	12.83
Front Two Panels Only Full Sun	103.5	7.81	13.26
Full Sun All Panels	208.6	14.8	14.1

Degrading Flexible Solar Panel surface:

Last Edit: Oct 7, 2018 15:56:04 GMT by rouelf

tattoo
Solar Connoisseur

Posts: 2,191

How To Check Performance Of Installed Solar System On RV Oct 7, 2018 0:48:42 GMT

Post by tattoo on Oct 7, 2018 0:48:42 GMT

To me it looks like you have a couple problems.... One is the time of year is with the sun being lower in the sky also your panels are braking down from age. Is there any way you could go with rigid panels? I think they would last way longer.....

Also covering up some of the panels and leaving them all hooked up together is a bad idea as you won't get a true reading... You need to unhook them all and check each one, One at a time..... I know it's a pain but that's the way it's done correctly.....

Last Edit: Oct 7, 2018 0:50:27 GMT by tattoo

rouelf
Solar Newcomer

Posts: 4

How To Check Performance Of Installed Solar System On RV Oct 7, 2018 16:24:31 GMT

Post by rouelf on Oct 7, 2018 16:24:31 GMT

Tattoo,
thanks for the comment. The flexible solar panels have only been installed for about 6 months. And only one of them is showing surface degradation (will have to look in the back when I replace it, to see which manufacturer does such a terrible job). Remember, the panels are from 3 different manufacturers, all Chinese made, hence relatively inexpensive. As such did not expect them to be the best. But As they seem to currently be performing / providing power at around 50 Watts each (50% of 100 Watts); then am ok with them for the time being. Even the one with the degraded surface is producing 45 Watts, is only about 16% below the other 3 panels. Had expected it to be a lot worse.
Usually I deplete the 4 (6 Volt connected for 12 Volts) house batteries to around 11.1 Volts overnight. And typically by 1pm, the batteries are pretty much fully charged. So the current system seems adequate.

Typically rigid panels require drilling on the roof, I prefer not to drill. The flexible solar panel are very quick and easy to DIY taping down on the roof.

Furthermore, don’t know yet, but I would guess under summer sun conditions solar panels, rigid or flexible, possibly don’t do better than 60% to 70% of their posted 100 Watts. So getting about 50% for this time of the year may not be bad. Will definitely monitor the solar system performance for aging degradation, and time of year.

… And you are correct, unhooking them and checking each one, one a time is the proper way to check them. Hopefully the flexible or rigid solar panels should have a diode to prevent cross talk (current going in the opposite direction) between panels. Will likely do that once and compare to results from having them all hooked up, and covering them up as in the initial post above. The idea is to go simple, + or - 8% off in accuracy is not a bad trade off for simple and fast.

As for quality and longevity of flexible solar panels, hence purchased the Renogy flexible panel, seems to be a better made panel. Will check it’s performance and compare to existing panels.

Thanks again !!