MPPT Solar controller questions

The difference is far from minimal, especially in the morning when the panels are cold, battery is low and sun is low.

Also my MPPT charger runs without any noise in the HF.

Have you ever tried a MPPT or going by your feelings? I have had both and the MPPT for over 2 years now. Love it.

Ah the old MPPT vs PWM debate, I thought it might pop up again !

For my use - 2 x 80W panels and a quite efficient Trailblazer fridge - I tend to agree that MPPT may not make much difference.

However, I'll buy one, and pay a little more for it, but only if it has the same display and switching capability as the Steca PR series. I'm rapidly reaching the conclusion that the Steca is worlds ahead of most in these areas.

Steca do make an MPPT controller, but only a basic model with a rudimentary display and no switching. I suspect they will eventually make what I'm looking for, so it's just a matter of timing - isn't it always ?

Yes, I do have one and have done extensive experiments to confirm what I have stated. I agree that it works best when the battery is well discharged.
As the battery charges, the benefit is less and I would on a fully sunny day get 42 Ah from my panels with the MPPT controller, and 38Ah with my standard controller. That is with the battery discharged to 11.5V. When I start with a battery at 12V, the difference is about 2Ah in favour of the MPPT. The money would be better spent on another panel if your setup allows it.
As for RF interference, it is real and it may or may not always appear on the frequencies you use. Because the MPPT is a variation of a switch mode power supply/charger, it WILL generate noise on HF. It is possible to minimize this, but out of the box mine was quite noisy.
So, no, it is just not my "feelings".

Hi Sorry to hear you have had such bad experiences with a MPPT controller. I have certainly had better experiences and regularly see gains of 25% in charge current.

I think you will also find that almost all solar controllers use switch mode / PWM / Pump charge type characteristcs and the interference is probably more a function of the quality of the controller. If you got lots of interference and poor charge improvement then perhaps it was the brand of controller at fault. Dunno, but I see no issues like that with mine ( Outback 60). I could not be happier. What model and brand is yours?

Hi Bookbbok,

Don't get me wrong, I am not saying that they don't work, it is just the the cost/benefit may be questionable. I have also seen a 25% increase in charge current, but that would only apply if the battery is quite flat. Over a whole day and with the panels in a fixed location, I have not seen what I would consider a worthwhile benefit. Having said that, the flexibility to use higher voltage panels in a 12V system or even connecting 2 12V panels in series is certainly a good feature. My unit is the small GSL MPPT12-1. They have gone to a bit of trouble to minimize RF interference, but they clearly acknowledge that additional measures may be required. They say "GSL MPPTs produce far less interference than conventional regulators DURING THE ABSORPTION and FLOAT stages and that is DURING MOST OF ITS OPERATING TIME"
I find that a bit strange, to me most of its operating time would be actually charging. You certainly don't need MPPT when the battery is already full!

Thanks guzzi, good info, and would make me feel better about buying one of their products if I go that way.

Hi Mick,

If you recall I bought the Travelander without fridges or panels so the MOF has indeed approved the necessary for a 40L Trailblazer, a panel or two, and a controller.

Thanks for the suggestions, and yes I have looked at the BMS, but it's a pretty pricey proposition, especially as I already have a solidly reliable SureCharge isolator and some heavy cable to the camper battery, thus making the BMS' isolation and DC>DC charging functions somewhat superfluous.

The Steca is only 220 clams, and the GSL combo is about 450, whereas from rough memory the BMS is over a grand, ain't it ?

However, I'll definitely talk to Redarc to see if their new unit has all the displayed info I want, in addition to having a main switch function.

Hey, your excellent online diaries are surely now publishable as at least one book, are they not ?

Will you be in the big smoke between Xmas and NY ? We're trying to get down to your fair state for a bit then, and will be in/near the city for a coupla days.

Please say a big hello to QV for me,

Cheers,

Nic

Hi jdwynne,

Yes, I admit to being very impressed (and perhaps spoiled !) by the excellent Steca PR-series controllers and their displays, which is why I'm finding it difficult to buy anything else (I sold my Steca with the old camper, fridge and panel) !

Thanks for your suggestions, I have seen the NASA monitors, but one of those and an MPPT controller from Steve is the same price as the total for the two GSL units, which also provide load switching. I could easily add a manual switch myself, but that'd be 3 separate units, whereas the Steca does all this in one !

Cheers,

Nic