ian81 Posted August 17, 2021 Share Posted August 17, 2021 Just installed new 2 x 100w panels and a votronic mppt controller. Green light on the controller shows charging. Off load the panels connected in parallet are showing 19.3 v. On connecting they only charge batteries at less than 1amp. The panels are wired using MC4 connectors. Disconnecting 1 panel and current drops to half. Battery voltage measured by a NASA marine monitor is 12.7 and it is showing capacity at 67%. Whilst the weather was overcast at times and panels part shaded I would have expected more. I am baffled. Any suggestions? Link to comment Share on other sites More sharing options...
spirou Posted August 17, 2021 Share Posted August 17, 2021 Sounds about right for overcast/partly shaded and regular low(er) cost panels. I would still wire in series though. 19.3 Voc is a bit low and won't leave the MPPT part much to work with. Link to comment Share on other sites More sharing options...
BruceM Posted August 18, 2021 Share Posted August 18, 2021 I would expect the trickle charge from the solar regulator to be over 13v when the battery is fully charged and much higher whilst charging discharged batteries. Firstly, I suggest you use a portable multimeter to confirm the voltage at the battery terminals concurs with your NASA marine monitor. If it differs then the Nasa data is questionable. I’m not aware how the NASA is wired in but if it’s the pass through type then I suggest you also check the voltage on entering the NASA and existing the NASA. Also, I assume that the regulator is the Duo model which also supplies a one amp charge to the starter battery? If so check the voltage at the starter battery, it too should be over 13v and will be a circuit that bypasses the NASA. I assume that you’ve double checked your solar regulator to batteries wiring. What habitation batteries are fitted and how old are they? Incidentally, I have a similar configuration to yours (2 x 100W panels). Today is overcast and the panels need cleaning. I’ve just been out to check and I’m showing approx 13.3v at the habitation batteries both of which are fully charged. Current, as you might expect, is minimal. As low power users it’s difficult to load the panels significantly. However in my experience in Northern France in November, after having the heating and lights on in the evening the batteries are registering as fully charged again by about 11.30am . Link to comment Share on other sites More sharing options...
ian81 Posted August 18, 2021 Author Share Posted August 18, 2021 Thanks Bruce The voltages measured with my Fluke are 12.67 leisure batts, 12.71 starter batery. Voltages on Votronic are 12.67 ouput and arround 17 on the input terminals. Nasa has a shunt that is in the leisure batteries negative and then all connections are from that, with a voltage measurement on the shunt and direct onto the leisure batteries. The leisure batteries are a pair of LFD 90's both bought 21 months ago. We are in SW France so would expect more than an amp as overcast here has been brighter than UK. Everything seems to point to both panels being faulty but how does one prove that? Link to comment Share on other sites More sharing options...
Steve928 Posted August 18, 2021 Share Posted August 18, 2021 ian81 - 2021-08-17 9:30 PM Green light on the controller shows charging. There are of course 4 green lights, used to determine which charge phase the controller is in - which one(s) is/are on? Link to comment Share on other sites More sharing options...
BruceM Posted August 18, 2021 Share Posted August 18, 2021 My set up is very similar, namely two 100W rigid panels wired in parallel, votronic duo solar regulator, twin LDF 90’s . Just checked and the solar input to the regulator is showing as approx 21.5 v which I think matches the on load spec of the panels. It seems unlikely that both panels would be faulty. Do you have the official spec for the panels, it would be interesting to know what under load output voltage they are expected to attain? Would you also confirm that you wired the starter battery charge output from the regulator direct to the starter battery – I just want to be certain that the starter battery voltage you posted is genuinely representing the regulator output. With regard to testing the panels, other than checking that their output agrees with their specification I’d not be able to provide useful advice. It is of course possible that the votronic is faulty and is dragging down the solar panel output voltage – someone with better electrical knowledge might be able to provide advice on how to test the votronic. Link to comment Share on other sites More sharing options...
ian81 Posted August 18, 2021 Author Share Posted August 18, 2021 ...the mpp light Link to comment Share on other sites More sharing options...
ian81 Posted August 18, 2021 Author Share Posted August 18, 2021 Re-installed the old PWM controller which shower the same result! Rechecked the wiring so everything points to the panels. Link to comment Share on other sites More sharing options...
Steve928 Posted August 19, 2021 Share Posted August 19, 2021 ian81 - 2021-08-18 8:13 PM ...the mpp light The MPP light shows only 'proper functioning of the solar controller' and not 'charging' which is indicated by the next lights above, so your controller doesn't appear to be indicating that charging is taking place. Link to comment Share on other sites More sharing options...
ian81 Posted August 19, 2021 Author Share Posted August 19, 2021 True for a 165 but not a 250 controller. Steve928 - 2021-08-19 8:21 AM ian81 - 2021-08-18 8:13 PM ...the mpp light The MPP light shows only 'proper functioning of the solar controller' and not 'charging' which is indicated by the next lights above, so your controller doesn't appear to be indicating that charging is taking place. Link to comment Share on other sites More sharing options...
colin Posted August 19, 2021 Share Posted August 19, 2021 ian81 - 2021-08-17 9:30 PM Whilst the weather was overcast at times and panels part shaded I would have expected more. Where the panels 'part shaded' for all your checked, if so then there is probably no fault with your panels, depending on the panels and there wiring just a small area of shade can cause a significant drop in output. Link to comment Share on other sites More sharing options...
BruceM Posted August 19, 2021 Share Posted August 19, 2021 ian81 - 2021-08-19 10:10 AM True for a 165 but not a 250 controller. Steve928 - 2021-08-19 8:21 AM ian81 - 2021-08-18 8:13 PM ...the mpp light The MPP light shows only 'proper functioning of the solar controller' and not 'charging' which is indicated by the next lights above, so your controller doesn't appear to be indicating that charging is taking place. I thought that it'd be useful if I posted this picture of my solar regulator in operation, not so much for the op's benefit but for anyone else wondering what the talk of mpp lights is all about. And yes the solar is connected, the angle of the cable just makes it look as though it isn't in this pic. Link to comment Share on other sites More sharing options...
spirou Posted August 19, 2021 Share Posted August 19, 2021 Like I said before, not at all surprising output. My 2x160W panels in series are currently producing 4W max while parked under a wallnut tree in south of Croatia. Link to comment Share on other sites More sharing options...
ian81 Posted August 21, 2021 Author Share Posted August 21, 2021 Solution!! Having revisted everything wiring etc I decided that it must be a panel issuie. Thanks to Amazon's speedy delivery I ordered 2 replament 100w renorgy's and plugging them in charging jumped from less than 1 amp to over 5. Thanks to everyone for their interest and suggestions. Link to comment Share on other sites More sharing options...
Ocsid Posted August 21, 2021 Share Posted August 21, 2021 ian81 - 2021-08-21 12:15 PM Solution!! Having revisted everything wiring etc I decided that it must be a panel issuie. Thanks to Amazon's speedy delivery I ordered 2 replament 100w renorgy's and plugging them in charging jumped from less than 1 amp to over 5. Thanks to everyone for their interest and suggestions. Were the defective "original panels", of the flexible [plastic] or ridged [glass] type? Link to comment Share on other sites More sharing options...
ian81 Posted August 22, 2021 Author Share Posted August 22, 2021 ...flexible / shingle pannels -no glass. Bonded to roof as per Ecoworthy's recommendation. Link to comment Share on other sites More sharing options...
Ocsid Posted August 22, 2021 Share Posted August 22, 2021 ian81 - 2021-08-22 7:53 AM ...flexible / shingle pannels -no glass. Bonded to roof as per Ecoworthy's recommendation. Thanks, it being a flexible unit does fit the pattern of what I sense on various leisure forums where solar panels are debated, shame as they overcome other issues, just don't seem as reliable. Link to comment Share on other sites More sharing options...
ian81 Posted August 22, 2021 Author Share Posted August 22, 2021 In removing then (used VHB tape) I noticed an oily foul smelling residue between panel and roof. I suspect strong sunlight and heat caused their demise. Link to comment Share on other sites More sharing options...
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