burtonwisher Posted August 19, 2019 Share Posted August 19, 2019 Hello all I'm hoping that somebody can help me understand an issue I'm having with a Motorhome I've just purchased. It's a 2010 Autotrail Apache 700 which has at some point been fitted with a solar panel and regulator which is connected directly to the leisure battery. The regulator is a generic PWM unit as in this link: https://www.amazon.co.uk/gp/product/B01J5A6X92/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1 Over the first couple of weeks that I had it, with much bright sunshine every day, I noticed that the leisure battery voltage dropped gradually from 12.6v to 12.1v, as displayed on the regulator, despite not being used at all (switched off at the control panel) The regulator has only ever shown the PV current as 0.0A So it seems to me that the regulator isnt charging the leisure battery. To be sure I replaced it with an identical unit, and got the same reults. Having disconnected the solar panel from the regulator, using a multimeter directly connected to the cables from the solar panel I measured: - Open circuit voltage = 48.9v - Short circult current = 2.03A So I'm now trying to figure out if this is 'normal', which would seem odd as the leisure battery voltage keeps dropping every day despite not being used. Or is there a problem somewhere, and if so, where? Any help appreciated! Kevin Link to comment Share on other sites More sharing options...
Charles Posted August 19, 2019 Share Posted August 19, 2019 The first thing I would do is get the battery on a mains charger before it gets any lower. That will also test if the battery will take a charge. Oh and welcome to the forum B-) B-) Link to comment Share on other sites More sharing options...
david lloyd Posted August 19, 2019 Share Posted August 19, 2019 Kevin, welcome to the forum. I am by no means an expert on these matters but if there is an output from the solar panel of +48v and yet the regulator is showing 0.0a flowing into the battery - coupled with the fact that the battery voltage is actually dropping - then I would think you are right and the regulator is not charging the battery. On one occasion this happened to me it turned out to be as simple as a plastic connector block being too loose and disconnecting the supply - easily and temporarily rectified by taping the connector together. Since then I have invested in a good MPPT regulator and upgraded the wiring to heavier cable which has improved the solar charge significantly. One other obvious cause of no charge to the battery is, of course, a blown fuse which should be located between the solar panel and the regulator. Hope this helps, David Link to comment Share on other sites More sharing options...
747 Posted August 19, 2019 Share Posted August 19, 2019 A solar panel output is usually in the low twenties volts, not 48. Is there just one panel or two? That sort of output would suggest 2 panels wired in series. I would imagine it would also fry a PWM regulator and probably some types of MPPT regulator. Link to comment Share on other sites More sharing options...
spospe Posted August 19, 2019 Share Posted August 19, 2019 747 is right. A solar panel intended for working in a 12 volt system, will have an off-load output voltage of about 22 volts. If you are measuring 48 volts, that says two panels connected in series, not parallel and the regulator has been fried. Link to comment Share on other sites More sharing options...
Charles Posted August 19, 2019 Share Posted August 19, 2019 spospe - 2019-08-19 7:25 PM 747 is right. A solar panel intended for working in a 12 volt system, will have an off-load output voltage of about 22 volts. If you are measuring 48 volts, that says two panels connected in series, not parallel and the regulator has been fried. That was my first thought but the regulator can take up to 50v in the specifications. Link to comment Share on other sites More sharing options...
plwsm2000 Posted August 19, 2019 Share Posted August 19, 2019 A couple of things that may be worth checking before changing the controller. 1) The controller you linked to has a temperature sensor. Is this sensor and its wiring ok? If not, the controller may think the battery temperature is too high and so shut down the controller. 2) The controller is for 12V and 24V systems. Generally you MUST connect the battery first AND THEN the solar panel, otherwise the controller could go into a weird state. Even if you get it working, you system is far from being optimized. A very basic PWM controller such as this doesn't use an inductor and is only a VOLTAGE converter (the output current is about the same as the input current). A MPPT (and some better PWM controllers) act as POWER converters and will boost the current while regulating the voltage and will be much more efficient with series connected panels. Your setup seems to be two panels wired in series so your controller will be dropping lots of volts and be wasting most of the power that could be generated. For example, if you have 2x 100W panels in series giving about 48V open circuit, these will be outputting about 40V when a reasonable amount of current is drawn. Your battery will only need around 14V so you are losing 26V or about 65% of the available power. In effect, your 200W solar panels will only provide 70W under perfect conditions. You should at least wire the panels in parallel (with blocking diodes) to have twice the current if you still wish to use this controller. Obviously a decent MPPT controller would be a better option. Link to comment Share on other sites More sharing options...
Mickt Posted August 20, 2019 Share Posted August 20, 2019 Why do you take it back to where you bought it. Link to comment Share on other sites More sharing options...
burtonwisher Posted August 20, 2019 Author Share Posted August 20, 2019 Thanks to everyone for the replies so far. I'm going to bring the van home later and check the things that have been suggested, then I'll update. There is definately only one solar panel on it but I'll have a closer look at all of the wiring. Link to comment Share on other sites More sharing options...
spospe Posted August 20, 2019 Share Posted August 20, 2019 burtonwisher - 2019-08-20 11:45 AM Thanks to everyone for the replies so far. I'm going to bring the van home later and check the things that have been suggested, then I'll update. There is definately only one solar panel on it but I'll have a closer look at all of the wiring. You will never get 48 volts out of a 12 volt panel, so something is wrong here. The normal off-load output from a nominal 12 volt panel is about 22 volts. It is possible that your panel is indeed a 24 volt panel (and thus has a 48 volts or so, off-load output). Are you sure you have your multi-meter set to read the right scale? All the 12 volt regulators that I have had, have had the ability to work on 24 volts as well. This has been done by connecting the regulator to the battery before the solar panel, if you do it the other way round, the regulator will assume a 24 volt system and fry the battery. It is quite likely that a 24 volt regulator could also have 48 volt working and the same effect apply. Is it possible that your regulator is in fact a 24 volt unit? Link to comment Share on other sites More sharing options...
plwsm2000 Posted August 20, 2019 Share Posted August 20, 2019 burtonwisher - 2019-08-20 11:45 AM .... There is definately only one solar panel on it but I'll have a closer look at all of the wiring. With an open circuit voltage approaching 50V, you must have a panel designed for 24V or domestic applications. A panel is made up of many cells all wired in series to increase the voltage up to a useful level. Most 12V panels have between 32 and 36 cells in series to give an open circuit voltage of between 20V to 23V. 24V panels have double the number of cells to give around 46V open circuit. This does not mean your panel is unsuitable for 12V systems, but as I said earlier, you need a suitable controller to get the full benefit of the panel. Link to comment Share on other sites More sharing options...
mikefitz Posted August 20, 2019 Share Posted August 20, 2019 Interesting. A number of points, firstly if the battery voltage is falling from 12.6 to 12.1 over a few weeks then something is draining the battery, there is some circuit active, perhaps the controller? The type of solar panel installed would be useful information. Nearly all 100 watt panels have a nominal OC voltage around 20 volts and with strong sun will have a SC current approaching 6 amps. One way to get an idea of the panel voltage is to count the cells and multiple by 0.6, thus a typical 36 cell panel will have a OC voltage around 0.6 x 36 = 21 volts. Is there a miss type on the 48.9 volt reading or a faulty meter reading, as this type of voltage would only be seen with large domestic panels over 300 watts or multiple panels in series. There are some very uncommon flexible solar panels that generate this type of output but not normally available in the UK. The generic type of PWM controller installed will have a hard time dealing with almost 50 volts if this is the panel output. In fact for a motor home installation this type of low cost controller is not recommended as it will most likely not drop to a float voltage once the battery is charged, possible leading to battery damage. They are designed for remote applications like lighting where the battery will be depleted over night. Fitting anything other than a quality MPPT controller from Victron or Voltronic is false economy. Not just for the improved yield but for the correct control of the charge process. Where there is doubt about a solar controller performance it is acceptable as a test to connect the output of solar panels of lowish power, say max 200 watts, directly to the battery for test purposes, continually monitoring the battery voltage and disconnecting when the battery reaches over 14.4 volts. Mike Link to comment Share on other sites More sharing options...
burtonwisher Posted August 20, 2019 Author Share Posted August 20, 2019 Hi everyone So after physically checking it in some more detail I can give an update. Firstly, there is definately only 1 solar panel, and I checked the readings again directly at the connectors coming from the panel on the roof, with a different multimeter to be sure. The readings are the same at 48V. So after doing some serious stretching with a barely-high-enough step ladder and using my inspection camera to reach under the panel to view the label, this is what it says: Panasonic HIT Power 240S Photovoltaic Module Maximum power = 240W Short circuit current = 5.85A Open circuit voltage = 52.4V Max power current = 5.51A Max power voltage = 43.7V Max system voltage = 1000V So not what I'd expected as the dealer had told me he believed it was a 100W panel, but I guess based on the replies already this would explain both the readings and the reason the cheap regulator it came with isnt working? I had already planned to install a Votronic MPPT controller following the advice that I'd seen in other posts on this forum....Is this is still possible with this panel? Attached are a couple of photos just so you can see it. Link to comment Share on other sites More sharing options...
spospe Posted August 20, 2019 Share Posted August 20, 2019 This panel is not suited to a 12 volt system as it is nominally a 48 volt unit.. The full specification for the panel can be read at: https://midsummerenergy.co.uk/pdfs/panasonic_240W_data_sheet.pdf You need a 12 volt panel and a suitable regulator as I suspect your regulator has been fried by now. Link to comment Share on other sites More sharing options...
plwsm2000 Posted August 20, 2019 Share Posted August 20, 2019 Unfortunately the Votronic regulator that most people recommend (Votronic Duo dig 250 etc) is only rated to 50V. Although your panel is only giving out 48V open circuit now (during summer), you will find that the open circuit voltage RISES at LOWER temperatures. On a cold winters day, the open circuit voltage will be above 50V and may damage the Votronic. As a minimum, you should look at the Victron Energy Bluesolar MPPT 75/15 that has a 75V max. input and 15A max output. The Smartsolar version is similar if you want the Bluetooth monitoring functions. Your panel will be fine with this controller. On a slightly different note, this panel seems to be designed to go on the roof of your house. This obviously doesn't see the same shocks and vibrations as your motorhome roof (although it can withstand a 140mph wind!). I don't know if there are any significant differences in their design for this. Link to comment Share on other sites More sharing options...
Paul- Posted August 20, 2019 Share Posted August 20, 2019 As the panel comes from midsummerenergy.co.uk and they are a decent and respected firm, I would give them a ring and ask what they would recommend, I bought my latest Morningstar controller from them (and it was a genuine one) at a very good price ;-) Link to comment Share on other sites More sharing options...
mikefitz Posted August 20, 2019 Share Posted August 20, 2019 I suggest fitting the Victron Smart Solar Charger 100/20 https://www.onboardenergydirect.co.uk/shop/Victron-Smart-Solar-Charge-controller-MPPT-100-20.html#SID=276 with Bluetooth, this allows you to check the status and history of the solar charging performance with an app on a smart phone. The system you have may just exceed 15 amps on a good day, the lower cost 75/15 will not be damaged by the panel power but I suggest going for the model with greater capacity. No connection with Onboard energy, a main Victron outlet, other than a satisfied customer. ( for a 15% discount use discount code JONOPROMO) Mike Link to comment Share on other sites More sharing options...
seaside-bill Posted August 20, 2019 Share Posted August 20, 2019 You’ve clearly got some issues with the solar panel fitted, but for what it’s worth, apart from your excessive voltage, the symptoms you describe are identical to a problem I had. I can get remote vehicle status reports via my Truma iNet so was able to easily check leisure battery status on a regular basis. I was getting the same voltage drop readings as you. Voltage would be about 13.4v after alternator charging and then reduce by about 0.1v every day or so, despite wall-to-wall sunshine. My solar panel was delivering about 22v on an average bright day. My EP Duo Solar Controller appeared to be charging the van battery, but not the leisure battery despite the indicator light suggesting otherwise. I swapped the controller for an identical replacement and, hey presto, problem was solved! I wouldn’t waste your money on a fancy expensive controller, just source the correct solar panel, replace the controller and I suspect all will be well. Link to comment Share on other sites More sharing options...
burtonwisher Posted August 20, 2019 Author Share Posted August 20, 2019 Thanks again for all of the input.....it's clear now where the issue is and what is needed. As a next step I'm going to replace the solar panel with a 'correct' 12v unit. It's a shame as it was a nice bonus getting a van seemingly complete with solar system already, but I'd rather pay for the right one than wing it with one that's not really intended for this purpose. Once that's done I'll be going for the Votronic dual controller in order to provide charge to both leisure and vehicle batteries. I've already got the extra cable from Sargent to connect to the EC225 control unit. I do like the spec of the Victron units but really want the dual charge functionality. Link to comment Share on other sites More sharing options...
mikefitz Posted August 20, 2019 Share Posted August 20, 2019 Why change a quality panel with the 'potential' to generate in excess of 15 amps with the correct controller, for a panel with a much lower output, you cannot have too much solar! There is nothing wrong with the panel you have, it seems to be well fitted with corner and central support brackets. You will find that its bonded to the roof and wont be easy to remove. I dont know why you think 'not really intended for this purpose', its just a solar panel slightly larger than the low cost Chinese 100 watt panels that seem for some strange reason to be the 'normal type'. I have fitted similar sized 200 to 300 watt panels on mobile installations with good reliability. The Voltronic dual controller does not charge the engine battery, it just provides a maintaining small current. This trickle charge facility can be provided by other small devices from Voltronic and CBE. if the solar controller has a single output. Mike Link to comment Share on other sites More sharing options...
spirou Posted August 21, 2019 Share Posted August 21, 2019 Exactly, the only thing to change is a good controller and I'll add another vote for a suitably sized victron. Link to comment Share on other sites More sharing options...
burtonwisher Posted August 21, 2019 Author Share Posted August 21, 2019 So if I go for the Victron 100 / 20 controller, can you point me to the additional device that could be used to trickle charge the starter battery? Link to comment Share on other sites More sharing options...
Paul- Posted August 21, 2019 Share Posted August 21, 2019 My vote would be to check all the connections before buying anything, and quick release battery connections would be replaced with good quality clamps. Oh and if its still the same phone midsummer energy :-S Link to comment Share on other sites More sharing options...
Wasnt Me Posted August 21, 2019 Share Posted August 21, 2019 Most importantly, go careful on the roof. Especially if you don't have the ideal ladder. There have been cases of people falling off and injuring themselves. I'm sorry if this sounds obvious and I do not mean to patronise :-D Link to comment Share on other sites More sharing options...
Alanb Posted August 21, 2019 Share Posted August 21, 2019 burtonwisher - 2019-08-21 7:03 AM So if I go for the Victron 100 / 20 controller, can you point me to the additional device that could be used to trickle charge the starter battery? Somthing like this. I am shure that there are others. Alan Link to comment Share on other sites More sharing options...
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