Extremely perplexing solar problem

[GILow]

Originally Posted by tanglewood

Looking at the specs for the Renogy controller and panels, you are running the controller out of spec. In particular, the controller can support a max of 260W of panels and you have 350W. There should be no expectation of it lasting any length of time, and it's no surprise that it has failed twice. What is surprising is that the first one lasted as long as it did.

Real controllers can be run over spec on wattage indefinitely, they just cap at their rated output. Not voltage though, that will nuke even the good ones.

[Rohan]

Originally Posted by tanglewood

For those using MC4 connectors (most solar panels), they can NOT be connected/disconnected under load. That may be why some people have had trouble with them.

That's a new one on me. I'll try throwing a sheet over the panels before connecting and see if that makes a difference.

[MVDarlin]

Recomnend Victron with panels wired in series. Less power loss over cable with higher voltage. Also, rated panel voltages are meaningless. You have to check output in actual location. Victron controllers will provide a lot more performance info with the phone app.

[Paul Reading]

I don't think that the OP is listening. Firstly he need a properly sized MMPT controller, Victron being the obvious choice. Secondly wiring in series is likely to yield more power for longer. He may need to replace a panel if indeed it is faulty. Whatever has happened over the last three years is irrelevant, it was poorly installed in the first place and to get a good result he needs to do it a different way.

There is an old saying, buy cheap buy twice...

[tanglewood]

Originally Posted by Rohan

That's a new one on me. I'll try throwing a sheet over the panels before connecting and see if that makes a difference.

It's stamped right on the MC4 plugs that I have used.

[OS2Dude]

Originally Posted by GILow

As said already... toss the Renogy stuff. It is utter crap.

Renogy has some issues with customer service, but so far their devices have done very well by me. Two 175W Flexible panels in parallel and one Rover 60A MPPT controller. Over 3 years old and still outputting per specs.

Try contacting Renogy support. (Online may be easier than phone.) I believe Renogy is based in Asia, so sometimes it can be difficult to get your idea across and sometimes their responses don't seem to make sense but keep at it and you will eventually get what you need.

[tanglewood]

I also see that the Renogy controller is Positive Ground. At a minimum, that means that it's essential that the solar panel negative circuit must be electrically isolated. It can not be grounded or in any way connected to the rest of the boat's negative circuit.


I would also check to see whether there is continuity between the controllers positive terminals and the controllers case and/or any grounding terminal. If the case is internally connected to the positive terminals, then the case will be at battery voltage and must also be isolated.


I have never dealt with any Renogy products, but from this little peek I would say they are living up to their reputation as utter POS. It looks like you get your money's worth, and are just buying landfill material.

[bill good]

Rohan, (Check your PM)
Progress clearing this snag seems a bit long for a simple fault!

Renogy does have not the best backup but if it is installed correctly & worked for 3yrs then I bet the fault is not the PWM controllers.
Hopefully Rohan will report the problem fixed soon!
Regards

[team karst]

Sometimes, internet "help" comes in many flavors. lots of well intentioned responses, most with good input. Here is mine: Reading this is like helping one measure tire pressure, without a tire pressure gauge.
My help: Get a clamp on DC ammeter/DMM. Maybe the best $50 you can spend if you live with solar. Isc and system current can be measured directly, not thru some suspect electronic controller and dash gauge....

[Kolchac]

A couple of advices from electrical engineer.
1.To measure voltage on a solar controller, you must disconnect the battery. It should be 17 - 20v for batteries 12 v.
2. Better using amp setting on you multimeter, series connection. Use scale 10A. Believe me your 350 W will never exceed 6A. If you expect miraculous result 30A, buy on aliexpress .com a loop DC ampermeter ($30) and hookup only 1 wire, + or -. I have one for my boat 30 ma - 300 a.
3. Do not connect your batteries in parallel if they are not designed for that, - they will discharge each other, even during charging from the solar, if current from solar is too low. Charge batteries one by one.
4. If your panel is 10%in shade, it will loose about 50-70% of current. Also altitude and angle matters.
5. Check setting of your controller - max voltage (13-14v)

[sailorboy1]

Originally Posted by Rohan

That's a new one on me. I'll try throwing a sheet over the panels before connecting and see if that makes a difference.

Will not made any difference for you now. If you did disconnect them in past and they are burnt, then they are burnt. My burnt one that caused the same indications as you was on the ground wire and I replaced with a standard crimp and heat shrink connector. Unless you plan to remove your solar panels regularly there is no reason to use those MC4 connections.

[Kolchac]

Originally Posted by MVDarlin

Recomnend Victron with panels wired in series. Less power loss over cable with higher voltage. Also, rated panel voltages are meaningless. You have to check output in actual location. Victron controllers will provide a lot more performance info with the phone app.

I’ve already explained how it works, just physics:
They convert (let’s say) 40 DC to 40 AC, because transformers work only with AC. Then transform 40AC to 20 AC, then convert 20AC to 20DC. As a result you loose ~30% of power. If you do not like transformers, you can use transistors and resistors and loose 80%.

[bill good]

Did try to add to my previous reply but the 30min clock beat me!
Another idea for a quick check of the solar panels, wiring etc would be to just take the PWM controller out of circuit & wire the panels direct to the battery. Approx 23 Amps will charge the battery BUT monitor the voltage while you do this test. Keep the voltage under 15V!! (In the days past the 17V called 12V panels were wired direct & a Shunt controller was put directly at the battery terminals & bypassed the higher voltage as heat.) If you don't get the approx 20A charge then you need to keep looking at the panels, connectors & wires from the panels. Plenty of cheap panels from upgraded home solar installations about these days.
Regards

[noelex 77]

Originally Posted by Kolchac

A couple of advices from electrical engineer.
1.To measure voltage on a solar controller, you must disconnect the battery. It should be 17 - 20v for batteries 12 v.

Correct, if you want to measure panel voltage.

Originally Posted by Kolchac

2. Better using amp setting on you multimeter, series connection. Use scale 10A. Believe me your 350 W will never exceed 6A. If you expect miraculous result 30A, buy on aliexpress .com a loop DC ampermeter ($30) and hookup only 1 wire, + or -. I have one for my boat 30 ma - 300 a.

30A is not possible, but 6A is an unrealistic maximum if measuring in full sun in areas of reasonable solar insolation. Around 15A would be typical. In perfect conditions if the solar panels are performing well, around 19A should be briefly seen. A clamp on multimeter is a safer way to conduct these measurements. Above 10A some conventional multimeters will be damaged. At least check the maximum current rating before using a conventional multimeter and don't expect only 6A.

Originally Posted by Kolchac

3. Do not connect your batteries in parallel if they are not designed for that, - they will discharge each other, even during charging from the solar, if current from solar is too low. Charge batteries one by one.

Boat house battery banks are typically composed of batteries wired (and charged) in parallel on all but the very smallest boats (with very rare exceptions).

Originally Posted by Kolchac

4. If your panel is 10%in shade, it will loose about 50-70% of current. Also altitude and angle matters.

Correct.

Originally Posted by Kolchac

5. Check setting of your controller - max voltage (13-14v)

Typical bulk charging voltages for lead acid batteries are 14.4v-14.8v depending on battery type and temperature.

[noelex 77]

Originally Posted by Kolchac

I’ve already explained how it works, just physics:
They convert (let’s say) 40 DC to 40 AC, because transformers work only with AC. Then transform 40AC to 20 AC, then convert 20AC to 20DC. As a result you loose ~30% of power. If you do not like transformers, you can use transistors and resistors and loose 80%.

This is a typical efficiency graph of a MPPT controller showing the variation as the solar voltage input voltage is changed (note this is for a 24v battery system). This is an Outback 80A controller.