MPPT Controller Explanation For Dummies

[noelex 77]

Originally Posted by goboatingnow

It's cam provide anything up to 25% boost which has been confirmed by several posters.
Dave

(my emphasis)

The average gain of a MPPT controller is what most boat owners want to know. How much more AHrs will their solar panels potentially produce thought the day. (Let's assume correctly chosen panels)
I got the impression from your posts that you felt the correct average figure was about 25%, but maybe we are just taking at cross purposes, and you were referring to a maximum. The maximium figure will, of course, be much higher and I agree 25% or even 30% will be seen in some conditions. However, most of the time the gain will be less, and there are conditions where a non MPPT regulator will actually produce more.

I believe the average gain a boat owner will see switching to MPPT (assuming correctly matched panels and no regulation so all the power is utilised) will be in the order of

5-15%

Perhaps if other posters could list what they believe is correct average figure it would help members plan their solar system and allocate the budget wisely.

[MarkJ]

Originally Posted by noelex 77

I believe the average gain a boat owner will see switching to MPPT (assuming correctly matched panels and no regulation so all the power is utilised) will be in the order of

5-15%

Mine does what appears to be 10% aprox. I don't really believe it.
Mine is the Solar Boost 2000E (Its not a three stage step down regulator either... it just reduces the amps when 'full')

What is essential for a solar array is an amp meter and a volt meter... and digital meters put in some convenient location are really quite expensive. I used to use my Multi Meter. A digital ammeter is $271 and a digital voltmeter is $229 but the Solar Boost 200E is $297 with both! Even analogue is above $100 for both.

So one can "save money" by buying an MPPT controller...


BTW PS The Solar Boost with 3 stage charging is $500.
I was a bit annoyed to find mine wasn't 3 stage charging. The instructions kinda lie.

[s/v Jedi]

Originally Posted by MarkJ

Mine does what appears to be 10% aprox. I don't really believe it.
Mine is the Solar Boost 2000E (Its not a three stage step down regulator either... it just reduces the amps when 'full')

What is essential for a solar array is an amp meter and a volt meter... and digital meters put in some convenient location are really quite expensive. I used to use my Multi Meter. A digital ammeter is $271 and a digital voltmeter is $229 but the Solar Boost 200E is $297 with both! Even analogue is above $100 for both.

So one can "save money" by buying an MPPT controller...

BTW PS The Solar Boost with 3 stage charging is $500.
I was a bit annoyed to find mine wasn't 3 stage charging. The instructions kinda lie.

Well, this thread has taught me it has this secret phase at night where it quietly consumes energy from your batteries so that they are run down extra in the morning...

[colemj]

Originally Posted by noelex 77

Perhaps if other posters could list what they believe is correct average figure it would help members plan their solar system and allocate the budget wisely.

I don't think there is an average - it completely depends on the installed system and area of operation. GBN makes the very good point of it depends on how mismatched the Vmp and Vo are.

Maybe a good rule of thumb is that a MPPT controller is the same as adding another panel? That was true for us - they both cost the same and produced the same increase. The MPPT was easier to mount .

Mark

[colemj]

Originally Posted by s/v Jedi

Well, this thread has taught me it has this secret phase at night where it quietly consumes energy from your batteries so that they are run down extra in the morning...

You are forgetting that old thread here where it was stated that moonlight gave positive output - thus negating the nighttime draw.

Mark

[noelex 77]

Non MPPT regulators should only be installed with panels of appropriate voltage. Fortunately most smallish panels are 36 cell nominally 12v panels which are ideal for a non MPPT regulator and a 12v boat system.
The Vmp of these panels is reasonably close under standard test conditions.
In practice, in real world conditions, the Vmp will vary a bit more primarily due to temperature and shadowing, but the variation (if we ignore unusual cases such as people cruising arctic areas) should be reasonably slight at least when averaged over typical operating parameters. The Vmp does not alter much with illumination.

As there is very limited, unbiased, published data, especially on boat systems I think the opinion of CF members may be a useful means to get to the truth.

The only proviso I would suggest is that people with controllers that display the input and output parameters don't base their estimation just on the display which will tend to suggest a gain greater than is really being achieved.

Sorry Mark I don't remember your system, lucky people with cats have room for lots of panels, but does equivalent of one more panel mean one more on top of 2,3,4,5,6, or ...?

[colemj]

Originally Posted by noelex 77

Sorry Mark I don't remember your system, lucky people with cats have room for lots of panels, but does equivalent of one more panel mean one more on top of 2,3,4,5,6, or ...?

Four 120W panels - 2 mounted on each side of a hardtop bimini. Wired 2 in series on each side with both sides in parallel.

Mark

[s/v Jedi]

Threads like these make it very difficult for those who want to buy into solar, so I'll write what I know really works here to give those readers an anchor point to tie their dynamic climbing rope to:

There are basically two possible setups: a few panels or lots of panels:

A few panels would be 3 or less. For this, buy the biggest Kyocera panels you can fit and a Genasun MPPT controller for each. This works better than anything else.

With 4 or more panels, it starts to make sense to buy one big controller for all of them. Again, buy the biggest Kyocera panels you can fit and an Outback MPPT Flex60 or even Flex80 controller. For panel wiring, make it flexible so that you can switch serial to parallel or any combination. The best setup is probably going to be with 2-6 panels on starboard all in series and the same (exact same number and type of panels) for port side and connect these two strings in parallel. The controllers can handle 150Voc which means 6 panels in series (check to confirm). If you have 4 panels on starboard you could put the two forward ones in series and the two aft ones in series and connect those two in parallel en mirror on the other side. Experiment a week or so with a setup and compare the kWh figures on the Outback controller.

I know there are cheaper panels and controllers; you can take your chances with them, I see no harm in that.

[SVNeko]

Thank you, Nick. That sort of thing is needed. But what kind of knot do we use to attach our climbing rope?

[hellosailor]

Hey Dave. "It's cam provide anything uptp 25% boost" Sure, the magic weasel words "up to". As a consumer I don't want to know what it might be able to do it the best possible situation, I want a number I can be sure of hitting. And from what I've seen in casual testing, and heard from different makers, "up to 25%" translates into "10% or better" and that's why I say 10%. Because you can pretty much expect a 10% gain from MPPT alone. Now according to one battery maker you can add another 5%+ gain just by switching from pure DC battery charging (which is what naked solar cells do) to any type of PWM charging (which is what MPPT controllers do) so perhaps that 10% should be restated as "15% gain over pure DC chargers or 10% gain over PWM chargers".
Numbers can be deceiving, installations will vary. If folks expect a ten percent gain over whatever else they had, in the worst case they'll be pleasantly surprised.

Mark-
I'm pretty sure the 2000E is the unit I spent a day testing and measuring. And no, it wasn't a "three stage" or any conventional "stage" type at all. What the folks at BS said is that it will measure battery voltage, and then apply maximum amperage at a slightly higher voltage, all the way through bulk phase. So if your batteries are down to 11.8V, it might apply 12V. As the batteries come up to 11.9, it might go to 12.1, and continue pumping maximum amperage into the batteries as it keeps staying ahead of the voltage. Exactly what they do is based on their own proprietary algorithm, which they considered a trade secret. (Yawn.) My hazy memory is that their logic is at least partly based on a look-up table on one of their chips, as opposed to doing just live calculations, but I may be misremembering that.

But from a battery maker, that was also confirmed as being better than any 'stage' charger, as apparently this scheme of "max amps, just enough volts, and keep changing it up" is also another way of adding charging efficiency. All MPPT controllers won't necessarily be the same that way either, the charging portion of each one, and the logic they use, may vary.
Give it another five years, ten years, and when you say "Three stage charger" people will look at you like you're fondly remembering the horse and carriage.

[Group9]

This has been a very informative thread. I have a Blue Sky controller for my two K-135 panels. I'm going to have to study it and this thread and figure out exactly what kind I do have.

I have to admit, that when I bought the panels I just asked them what I needed and what I needed to do with it and that's what they gave me.

[MarkJ]

Originally Posted by hellosailor

Mark-
I'm pretty sure the 2000E is the unit I spent a day testing and measuring.
.

Interesting stuff. Thanks for that

[hellosailor]

9-
When I was testing a setup, monitoring voltage and amperage every 15 minutes for most of a half day, one of the quirks I found was that my two multimeters were 0.4v different when reading the same voltage. So while monitoring the panels and charger output are a good idea, "Trust but verify". If you are monitoring raw panel output versus MPPT controller output and using two meters to compare them live, first compare and calibrate the meters.
FWIW.

[Mystic38]

Completely agreed..

So i will add my own input to your practical list.. the portable single panel setup.

I own a Sabre 38.. no real room, $$, or interest in a permanent installation.. and, as its impractical to have enough solar to satisfy offshore passages, prior to my first bahamas trip I scaled a system for self sufficiency at anchor..

I have.. One single 130W panel. it measures 56" * 26".. chosen as its the max size that is easily manageable... ie this can live under a single bunk when on shore power or passsagemaking.. When at anchor it can be on the boom, tied to the lazy jacks, or placed on the foredeck.. 12ft leads go below to the MPPT charger, which simply plugs into a cigarette lighter socket, either in the V-berth, or at the nav station.

like many, 90% of the daily consumption at anchor is the fridge/freezer, in my case its an air cooled adler barbour, and in sunny conditions, batteries are easily to 100% by 2pm.

I could read the well intentioned opinioned debate in this thread 500 times, but for me, the facts are still the facts... charging current increased by 25% due to the MPPT controller... and without that I would have had no reserve charging capacity to recover from partly cloudy or full rainy day....

Originally Posted by s/v Jedi

Threads like these make it very difficult for those who want to buy into solar, so I'll write what I know really works here to give those readers an anchor point to tie their dynamic climbing rope to:

There are basically two possible setups: a few panels or lots of panels:

A few panels would be 3 or less. For this, buy the biggest Kyocera panels you can fit and a Genasun MPPT controller for each. This works better than anything else.

With 4 or more panels, it starts to make sense to buy one big controller for all of them. Again, buy the biggest Kyocera panels you can fit and an Outback MPPT Flex60 or even Flex80 controller. For panel wiring, make it flexible so that you can switch serial to parallel or any combination. The best setup is probably going to be with 2-6 panels on starboard all in series and the same (exact same number and type of panels) for port side and connect these two strings in parallel. The controllers can handle 150Voc which means 6 panels in series (check to confirm). If you have 4 panels on starboard you could put the two forward ones in series and the two aft ones in series and connect those two in parallel en mirror on the other side. Experiment a week or so with a setup and compare the kWh figures on the Outback controller.

I know there are cheaper panels and controllers; you can take your chances with them, I see no harm in that.

[foggysail]

Originally Posted by goboatingnow

Yes but that has nothing to do with pwm solar regulators. There's no inductor and they are not buck or boost

Dave

My comment on PWM does apply to solar power regulation. Suggest that you look at the MorningStar ProStar PS-30 PWM.

And sure, on the cheapy side of regulation one can configure a plain old power mosfet as a switch giving the same function as a piece of wire until the load voltage reaches the desired voltage. At that time the mosfet can be modulated or simply left as an open circuit. Very crude!

MorningStar uses the buck instead. I installed one last year on my boat. No clue how others achieve so called PWM.

Foggy