Solar controler

Discussion in 'Mech Tech' started by Rich83, Jul 16, 2019.

  1. 100 watts of panels has a max of about 8 amps of output in perfect conditions so you need a 10 or 20 amp controller max. 20amps will allow expansion if you want to.
    garethpuk likes this.
  2. Lovely thanks.
  3. That eBay controller will do. Its quality Pearl River Opium wars revenge ..
    Its MPPT brand with a China Export mark on it..

    I have one because its really cheap and nasty. Dont bother with the switched output just connect the solar panel and the battery to it. To save a few pennies, it switches the negative side, all the positives are joined together, so put a 10A fuse between the battery and the battery connection of the regulator.

    The EPEver Tracers which are the real deal cost a lot more. I was keeping the cost down because my panels were free, corroded secondhand ones.. now I am sure they work I will chuck this regulator on the boat to go with a 20 watt panel and buy or build an MPPT controller to go with my 2x100 watt panels on the bus roof.
  4. Currently got a cheap PWM controller that came with the JK solar panel kit - reading around, I'm thinking to upgrade to the EPEver Tracer MPPT controller as you suggest. For one 100 watt panel, and possibly adding a second 100 watt panel at a future date, which EPEver Tracer would you go for?. Would a 10A one suffice? Like this...? Thanks!
  5. The rating of the controller is based on the output current. So for a PWM controller, you will get about 10A max from two 100 watt panels , based on 5 amps each at 20 volts from the panels. Its just a switch connecting or disconnecting the panels.

    With MPPT, it stores energy at 20 volts and dumps it at 12 volts, effectively a step down transformer, so each panel can push about 8 amps (100 watts) to the battery. A 20 amp MPPT regulator is needed.
  6. If you’re looking at an initial 100w, but definitely thinking of adding another in the future, you’d be better going for the 20a controller as 10a is fine for up to a 120w panel but not anything over that.

    Edit, ha just realised Mike beat me to it, and much more scientifically!
  7. Thanks Mike - 20 Amp MPPT it is then. I just ordered a Leoch 110Ah AGM battery - with one 100 watt panel, and the 20A MPPT controller, do you reckon I'll have enough power to keep a new Dometic CRX50 fridge going? (fridge is 40 watt power consumption). Thanks again for the help.
  8. Appreciate the help mate, all this solar panel stuff is a steep learning curve!
    scrooge95 likes this.
  9. According to Dometic, your fridge uses 0.25 to 0.5KWh of power a day.
    A 110AH AGM battery stores effectively about 1kWh of energy, so enough for a couple of sunless days.
    A 100 watt solar panel might be able to put in say maximum of 0.8KWh : 8 hours of bright sun, in the UK often much less.

    The numbers all work out but you MUST recharge the AGM battery when it goes flat or it will be dead a couple of days later - a price you pay for the deeper cycle capacity.
    This would mean turning off everything if on solar and hoping...
    theBusmonkey likes this.
  10. ^^^
    ...and that's why 200w, if you can afford it, is a much more suitable set up in the long term.
  11. Thanks for the advice Mike, will be sure not to let the battery stay flat for too long, and once summer is out the way will fit an extra 100w panel. I'm off to France for 3 weeks so hopefully will get plenty of rays.
  12. Cheers, yeah I reckon it has to be done.
    theBusmonkey likes this.
  13. By the way, is there any merit in getting the WiFi Box with the EPEver MPPT controller? Where I'm putting the controller is in a semi-accessible place, does the WiFi box gives you any extra data (or better presentation of data) that's worth getting it for? If any of you have it...@mikedjames @theBusmonkey @scrooge95
  14. I don't but @pkrboo has a remote meter that he can't drag himself away from on sunny days:p
    Lasty, scrooge95 and Ged Richardson like this.
  15. Last edited: Jul 19, 2019
  16. Once it's all up and running and working what is there to do? must be like watching paint dry :rolleyes:
    theBusmonkey likes this.
  17. The Victron brand is also well thought of - used by professionals too..
    Ged Richardson likes this.
  18. It sort of turns into this weird competition of comparing efficiency and output.
    I imagine its a little bit like fishing....
    pkrboo likes this.
  19. Yeah it looks like decent gear. Cheers

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