pilchard Posted January 17, 2019 Share Posted January 17, 2019 I today recieved two replacement semi-flexible solar panels... an 80W and a 50W. Bitter experience has taught me that I would be wise to test them before I glue them onto the roof of my campervan. I have a 10 amp multimeter, so can anyone give guidance on testing them out... with or without connection to my leisure battery and/or MPPT controller? What with the current cold bright weather, if I point them at a 90 degree angle to the sun then I might get some half decent values. Link to comment Share on other sites More sharing options...
mikefitz Posted January 18, 2019 Share Posted January 18, 2019 Unlike many power sources a solar panel is limited to the maximum current (the short circuit current) it can deliver, so there is no worry about shorting the output wires The ratings should be on a label on the panel or literature provided. Without connecting the panels to anything, first measure the panels open circuit voltage with the meter set to the 200 volts DC range (assuming a typical low cost multimeter), connect the probes on the meter to V and Common and then connect to the panels cables ( if they have MC4 connectors you may have to adapt temporary pieces of wire to make a connection) From your other posts it sounds that you have had to make measurements before so you may already have a method sorted. With some sunlight you should see over 20 volts, typically 23 volts, the open circuit volts of the panel. With varying sun intensity the voltage should not vary too much. Disconnect the probes from the panel and select the 10 amp range on the meter and move the red meter probe to the 10ADC terminal. To measure the short circuit current, connect to the panel cables, you should see a current value of 'not very much' to 2 to 3 amps ( from the larger panel, about half from the smaller) depending on the angle of the panel and the degree of sunlight. Having completed the measurement return the settings and probe position on the meter to the voltage measuring state. If its fairly easy to connect to the MPPT before mounting the panels then you should see some activity from the controller with power going to the battery. When you connect up the panels they should be connected in parallel to get the possible 130 watts, if you connect in series then you are limited to twice the smaller panel current and thus power, 100 watts. (assuming the panels have similar open and max power voltages). Mike Link to comment Share on other sites More sharing options...
pilchard Posted January 19, 2019 Author Share Posted January 19, 2019 Thanks Mike. That seems to be the kind of advice I was looking for. I now have to wait 'till we get some sunshine. I'd figured on propping them up, 90 degrees to the sun, against our south facing kitchen window and testing them singly; then propping them up on the roof of the van in order to wire into the leisure battery and test them out singly and in parallel... both with the controller and without. Having not yet tested the controller, I had wondered whether or not... if it were faulty... it could damage the new panels. Will get back with some readings, but might also need further clarification/hand holding/education. John Link to comment Share on other sites More sharing options...
pilchard Posted January 23, 2019 Author Share Posted January 23, 2019 I tested the new panels today at approx 90 degrees to the bright winter sunshine at our kitchen window and got 23.5V/0.39A from the 60watt panel and 21.5V/0.6A from the 80watt panel. I then took them both to the van and connected the 60watt direct through to the battery (who's current charge level is 12.6V), and without controller in the loop. The panel was propped up loose on the roof to gain max 90 degree angle to bright sun. With meter on 10amp, neg panel lead connected to neg battery, poz lead from panel disconnected from battery. Poz probe to poz panel, with neg probe switching between both poz and neg battery terminals. Results..... nothing.... zero. What the hell is going on?!!! That is when I just lost it and had to accept that these kinds of electronic black arts are beyond me. Maybe I'm just making a simple error, or maybe I should have taken more notice during those physics lessons at school. The van has to go in early next week to have the Truma blown air heater serviced (suspected CO emmision) so I phoned them up and they agreed to also check my new panels and system out. I'm pretty hands-on, and fairly good at fault diagnosis and problem-solving, but generally with stuff I can get my 5 senses around. There comes a time when you just have to admit lack of knowledge, experience, confidence and....... patience. If anyone knows of a really good PV man in the North Lakes/Cockermouth area, I could do with his contact details... just in case my service people can't work it out. Will post up how I get on. Link to comment Share on other sites More sharing options...
Paul- Posted January 23, 2019 Share Posted January 23, 2019 pilchard - 2019-01-23 5:17 PM I tested the new panels today at approx 90 degrees to the bright winter sunshine at our kitchen window and got 23.5V/0.39A from the 60watt panel and 21.5V/0.6A from the 80watt panel. I then took them both to the van and connected the 60watt direct through to the battery (who's current charge level is 12.6V), and without controller in the loop. The panel was propped up loose on the roof to gain max 90 degree angle to bright sun. With meter on 10amp, neg panel lead connected to neg battery, poz lead from panel disconnected from battery. Poz probe to poz panel, with neg probe switching between both poz and neg battery terminals. Results..... nothing.... zero. What the hell is going on?!!! That is when I just lost it and had to accept that these kinds of electronic black arts are beyond me. Maybe I'm just making a simple error, or maybe I should have taken more notice during those physics lessons at school. The van has to go in early next week to have the Truma blown air heater serviced (suspected CO emmision) so I phoned them up and they agreed to also check my new panels and system out. I'm pretty hands-on, and fairly good at fault diagnosis and problem-solving, but generally with stuff I can get my 5 senses around. There comes a time when you just have to admit lack of knowledge, experience, confidence and....... patience. If anyone knows of a really good PV man in the North Lakes/Cockermouth area, I could do with his contact details... just in case my service people can't work it out. Will post up how I get on. Suspected CO emission? Why do you suspect that, only an overcharged battery can give off gas that sets the CO detector off. I had a Steca controller that cooked one of my batteries and one of the reasons I prefer to use Morningstar controllers Link to comment Share on other sites More sharing options...
plwsm2000 Posted January 23, 2019 Share Posted January 23, 2019 Unless you really know what you are doing and you are very careful, it is best not to connect the solar panels directly to the battery without the controller in place. The battery will normally limit the voltage to 13-14V or so but If the battery was to become disconnected, even for a very short period, there is a danger of applying the 22V from the panels directly to the van 12V electrics (fridge & heater controllers, EBL etc.). The battery will also be damaged if you left it connected for any length of time. Personally, I wouldn't risk it without isolating the whole 12V van electrics first. That said, the way you have connected the panels should give some current during your test. The fact that now the panels are on the roof would suggest you have some extra wiring between the panel and where your battery is located?. If so, could you have an open circuit somewhere? The normal MC4 solar panel connectors are not easy to temporary connect to using standard DMM probes. Is it possible you have blown the fuse in the DMM current input? If you accidentally connected the DMM across the battery, even momentarily, this will take out the fuse. Most DMMs will read over range if this happens, but some DMMs might read 0. Make sure your DMM is still set to read DC current (AC current will read 0 in this set up) I would forget about connecting to the battery for now and just check for the open circuit voltage first. Once you are happy that you are seeing the open circuit voltage at the correct place, then start looking at the current. Good luck. Link to comment Share on other sites More sharing options...
mikefitz Posted January 23, 2019 Share Posted January 23, 2019 As Phil suggests its possible that you have blown the fuse in the 10 amp circuit of the meter, its very easy to do this. There is a small fuse inside that can be replaced . The initial test you carried out with the panels on their own seem about right for the conditions, so the panels were working at that stage. Connecting directly to the batteries is possible for a limited period provided suitable precautions are made as suggested. Its quite difficult to damage a panel whilst testing unless its connected to the battery with reverse polarity. Damage may occur under this condition. Hopefully everything is OK, but I suggest you repeat the initial tests again with the panel connected to nothing else other than the meter, to ensure the panels are working, before you fix the panels to the roof. Mike Link to comment Share on other sites More sharing options...
pilchard Posted January 24, 2019 Author Share Posted January 24, 2019 Paul... it is the heater producing the CO. We have Fire Angel CO detector in the van and every time the heater is used for 30 or 40 minutes, it sets the alarm off. The alarm readings are relatively low, and according to the alarm instructions only dangerous if run like that for considerable time. I called it suspected CO because it is just possible the detector might be misreading, but the service guys have their own detector probes and... better safe than sorry. Link to comment Share on other sites More sharing options...
pilchard Posted January 24, 2019 Author Share Posted January 24, 2019 Plwsm2000 & mikefitz..... I think the defining caveat here is "unless you know exactly what you are doing". I don't. I give in. My brains are fried and I don't want to now fry any panels, controller, battery, or anything else. Time to pay someone who does. It decided to do this installation myself because all available info and advice claimed it was simple plug & play... providing correct proceedures were followed, which they were. The connection part was easy, it was the planning, optimizing roof space and wattage, and working out the best cable routes that was challenging. By following correct proceedure you don't need to be a PV expert, but when things go wrong you do. No, honestly... I've had enough. Link to comment Share on other sites More sharing options...
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