Which Solar Charge Controller?

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  • :sunsmile:
    I've ordered a 100w 12v monocrystalline solar panel and am looking at those solar charge controller jobbies.
    They seem to start in price at around £11 and then upwards.

    Does anyone have any thoughts on the best to go for, and whether they have differing efficiency levels, and whether a good LCD display of information is worth the extra outlay? Money is very tight (when wasn't it!) so I'd really appreciate the benefit of your wisdom.


    Thank you,


    Dave.
    :sun:
    PS I already have a little blue LED voltage readout connected to my leisure battery which for £3 is brilliant value (and funtustic use of spairce).

    Not a shred of evidence exists in favor of the idea that life is meant to be serious.

  • A voltage/battery state display is worth the extra money. If only for peace of mind that the sun is doing its job. If your happy with the LED voltage meter set up you have for battery state. I would look at facility to add more panels through controller and any overload/safety functions before going cheapest.

  • Lionheart,


    In principle, I'd say that if you pay a wee bit more, you'll ge a solar controller which will really take care of your battery.


    A basic controller will stop your batteries from being over-charged and will warn you when they are getting low then cut the load when the batteries are under (say) 11.5 volts.


    A good one (Steca, Morningstar, Phocos etc.) will do that plus it will will take your batteries up to a higher charge (Around 14.5v) to perform an equalisation charge. Equalization charging is the deliberate process of charging a battery or battery bank at a high voltage for a set period of time to remix the electrolyte and de-stratify the internal plates. Equalize charging helps to remove sulfate buildup on battery plates and balances the charge of individual cells. This will help your battery to last longer.

  • I totally agree No Fixed Abode ! I wouldn't buy a MPPT controller for a small 12v system - better to use the money (If you have it !) to buy an extra solar panel.


    I've installed a lot of very cheap controllers (£8 - £10) in vans and yurts etc. They're really difficult to work with, the tiny metal connection bars break easily and I've had several fail after only a couple of seasons. Batteries tend to last only a few years as they're simply run on a float charge and not de-stratified regularly.


    There are two Steca controllers at a good price on Ebay at the moment :


    £38 (Good for two 100 watt panels) : http://www.ebay.co.uk/itm/STEC…2020-20-AMP-/141127566953
    £45 (Will control up to 3x100w watt panels) : http://www.ebay.co.uk/itm/STEC…3030-30-AMP-/141127567560


    I have an old 30 amp Steca (This manages 300 watts of panel run in parallel with a little Rutland 910 wind generator) In fact, I'm typing this on a laptop charged with this system which does all our upstairs lighting and has worked perfectly for the past 15 years. I replaced the entire 600ah battery bank once about four years ago and two of the original batteries are still in use !


    old steca controller equalization charge.jpg


    What are you going to use the energy you produce to do Lionheart?

  • I have 2 x 170W mono panels going through a 30A pwm controller off ebay to 2 x 110ah batterys linked together. All seems well at the moment but only been using for a couple of months. I know feck all about electrics and wondering if I could add another battery

  • Hello Curro,


    You're the person in the best position to answer that question. ;)


    If your batteries are staying at or near a full charge at this time of the year as we're approaching the winter solstice, then I'd say that you could add another battery. If they are simply floating around 50% - 75% then you shouldn't add another battery.


    As the days lengthen again after the solstice, your panels will provide you with more energy and it's a shame to waste it. One of the big problems with solar is that in winter, having too much storage means that your batteries are not being charge enough to keep them in good condition. That's why many people advise charging the batteries in winter once or twice a month with a generator or a domestic battery charger. Some people even take batteries off the system and keep them charged with a charger ready for spring. Another way of assuring that the system balances out is having a wind generator which will keep your batteries topped when there's wind but not much sun - that usually works well for wintertime.


    Ideally, you should add a battery exactly the same as the ones you already have and as the system has only been running for a short time the age of the battery shouldn't need to be taken into consideration.


    A battery bank should consist of batteries all the same, otherwise the newer batteries (or the batteries with more a/h) will perform at the same level as the other ones and your system will be less efficient.

  • Thanks for that HWH, I think I need to get some meters ie. amp, volt, sure I have some stored somewhere and find out how to wire them in so I have a readable indication of whats going on. The controller I have only has an LED which is either green, orange or red and when I have the tv on at night it usually goes into the red but back to green in the daylight.


  • Thank you everyone for your kind input (pls excuse pun). Going to enjoy reading through for education and to put it to use.


    Hi HWH, my panel will go via the controller to a 110AH battery to power led lighting, a TV and the water pump - daily shower and general sink stuff. At the moment I charge it from home, from a crappy little 700w Chinese generator or from the split-charge relay.
    I keep a second battery, an 85AH one but I switch them over rather than making the mistake of trying to charge two differing batteries. I'm thinking 2 x 100w panels though only one on order at the moment.

    Not a shred of evidence exists in favor of the idea that life is meant to be serious.

  • I have a cheap charge control i got for under a tenner on ebay
    Works a dream looks after it seemingly well it looks and hooked up to my 100w poly
    It was still pulling amps at half 4 when it was pretty much almost black out

  • hi lionheart, have you seen this website, i was wondering how good these panels were, they seem pretty cheap!im now thinking of going for a 200)watt panel instead of a 100 watt. some control boxes on there too.
    http://www.bimblesolar.com/delivery

    Thank you everyone for your kind input (pls excuse pun). Going to enjoy reading through for education and to put it to use.


    Hi HWH, my panel will go via the controller to a 110AH battery to power led lighting, a TV and the water pump - daily shower and general sink stuff. At the moment I charge it from home, from a crappy little 700w Chinese generator or from the split-charge relay.
    I keep a second battery, an 85AH one but I switch them over rather than making the mistake of trying to charge two differing batteries. I'm thinking 2 x 100w panels though only one on order at the moment.

    Create Your Own Minority Cultures As The Majority Are Merely Sheep Meat For The Vultures!

  • I had one of these:
    http://www.ebay.co.uk/itm/Sola…dgets&hash=item3a85d6ce8e
    and although it did the job it was a bit slow on the uptake (its range wasnt so good).


    Got one of these:
    http://www.ebay.co.uk/itm/10A-…&var=&hash=item51aba66051
    They were £16 at the time :( but now cheaper.


    If you can afford one get something like this:
    http://www.ebay.co.uk/itm/5-10…&var=&hash=item43c00c1ef2
    (MPPT) - for a 100w panel into 12v the max/peak volts will be 18v. Max current therefore just under 6A. Get a bigger unit (say 20A) and when you add another panel you wont need to get a new controller.
    MPPT (if you dont know any physics) basically means that for each light level outside the controller adjusts itself so as to get the best off the panel. For those who do know some physics, it looks at the open circuit o/p (derived from the light level) and battery voltage, works out internal impedance of panel and adjusts the PWM so as to optimise power delivery (based on that formula that I cant remember for optimising power from a current generator that has internal impedance). Physics lesson over.


    BTW top tip: I got two of those domestic panels (300w) out of a skip becuase the glass was bust (so what - still works) - these are 36v open circuit / max power but arranged in 3 banks of 12v. So I use 2 banks (3rd bank disconnected) giving me 24v max. The max input on the controller is 25v... ok close I know but been working well for some time. And seeing as they came from a skip.


  • good info , but just looking at that thrird link, is that defo an MPPT box, it looks like PWM, and the price would suggest that too, humm just wanna make sure.

    Create Your Own Minority Cultures As The Majority Are Merely Sheep Meat For The Vultures!