The importance of regulator on solar efficiency

[gauvins]

I've installed solar panels (3x70W) something like 5 years ago. I've never measured the number of Ah harvested, but plan to do it starting this year.

At the time I've purchased a regulator without thinking about it. I recently read that the way in which a regulator works had a considerable impact on solar panels' effectiveness.

Does it really make a difference? (i.e. worth spending the money on a new regulator)

[CatNewBee]

Originally Posted by gauvins

I've installed solar panels (3x70W) something like 5 years ago. I've never measured the number of Ah harvested, but plan to do it starting this year.

At the time I've purchased a regulator without thinking about it. I recently read that the way in which a regulator works had a considerable impact on solar panels' effectiveness.

Does it really make a difference? (i.e. worth spending the money on a new regulator)

Yes.

But as always it depends.

First of all, it depends on the electric specifications of your panels (Vmp,Imp),
Second on the way they are connected to each other,
Third on the type of batteries and voltage you use.

Tho controller must provide the maching charge regime for your battery chemistry, there are differences between FLA, GEL, AGM etc. or it must be programmable, so you can set it up propperly. The important values are ABSORPTION VOLTAGE, ABSORPTION TIME, FLOAT VOLTAGE, RECONDITIONING VOLTAGE, RECONDITIONING INTERVALL.

Reconditioning should only be enabled on unsealed FLA batteries, GEL, AGM and SMF FLA must not be reconditioned.

Then you have the choice between PWM and MPPT controller.
MPPT is only efficient, if the solar voltage Vmp / or the string voltage if you connect the panels in series - is at least 4V above the ABSORPTION voltage recommended for your battery type.

If the difference is less than 4 volts, a PWM controller might output the same or better results than a MPPT controller, especially in hot climates.

The specification of the controller must match or exceed the power ratings of your solar array output. Important parameters are max input voltage, maximum input current, maximum output current.

The wrong controller or poor configuration can wrack your batteries over time.

[gauvins]

Hmmm...

As I said, I have 3x70W panels. I am considering the Victron MPPT 75 l 15 A. (Read somewhere that the 30A was designed for systems up to 700W.

House batteries are 3x230Ah FLA.

Will this work?

[thomm225]

Amps = watts /volts gives you some idea...

So if you had 700W you'd probably need a larger controller than one rated at 30A (but it depends on the load to see how many amps (amount of current flow) would normally be drawn in your system)

You can look up all the details online as to how to properly figure out controller size.

I have 85 watts worth of panels and a 20W PWM controller charging two 12 volt batteries in parallel

[gauvins]

Well... Victron 30A is supposed to be handling arrays rated at 700W. A sales rep told me that their 75 | 15A MPPT could handle my setup...

[Pete7]

Yes and we have that model attached to a 150w solar panel, it will handle your 3 x 70w panels. However, it won't handle 700w of solar, see link below. Buy either the dongle or USB lead to connect it to a laptop and mount it somewhere you can reach it as the Victron display has some interesting information you will want to monitor regularly.

Pete

https://www.victronenergy.com/upload...-100-15-EN.pdf

[CatNewBee]

Originally Posted by gauvins

Hmmm...

As I said, I have 3x70W panels. I am considering the Victron MPPT 75 l 15 A. (Read somewhere that the 30A was designed for systems up to 700W.

House batteries are 3x230Ah FLA.

Will this work?

yes, it can. How are your panels connected to each other and to the controller and can you provide the panel specifications please. Otherwise it is guess work.

[thomm225]

Originally Posted by gauvins

Well... Victron 30A is supposed to be handling arrays rated at 700W. A sales rep told me that their 75 | 15A MPPT could handle my setup...

Yep, it's all in the details.

At 24 volts, spec's say this 30A Victron 100 / 30 Controller will handle 880 Watts but at 12 volts 440 Watts. (I was thinking 12 volts above)

https://www.amazon.com/dp/B073ZJ3L13...a-396611007572

[john61ct]

Yes, but don't think it's worth going to 24V just to save money on SCs 8-)

[gauvins]

(After some digging and reading)

Solar panels specifications indicate maximum Voltage and maximum Amps. In my case, the figures (printed on the panels' backsides) are 21V and 4.7A per panel. Multiply by 3, and the numbers should be less than the regulator's rating. Which is 75V | 15A in my case. (Panels connected in series of parallel will add Voltage or Amps)

So all is good.



(My confusion was rooted is assuming that the critical Amp value was calculated at the nominal 12V. Not so)

[travellerw]

Originally Posted by gauvins

(After some digging and reading)

Solar panels specifications indicate maximum Voltage and maximum Amps. In my case, the figures (printed on the panels' backsides) are 21V and 4.7A per panel. Multiply by 3, and the numbers should be less than the regulator's rating. Which is 75V | 15A in my case. (Panels connected in series of parallel will add Voltage or Amps)

So all is good.



(My confusion was rooted is assuming that the critical Amp value was calculated at the nominal 12V. Not so)

No hold onto your hat... You are about to get a ton of responses on Parallel vs Series)..

In case you want the TLDR: version.

Series - Mostly good on Catamarans with minimal to no shade. Advantage of using smaller and less wire.

Parallel - Great on Monohulls and Catamarans that have numerous shading items (booms, stays, ect). More expensive install due to needing heavier wire.

[CatNewBee]

Originally Posted by gauvins

(After some digging and reading)

Solar panels specifications indicate maximum Voltage and maximum Amps. In my case, the figures (printed on the panels' backsides) are 21V and 4.7A per panel. Multiply by 3, and the numbers should be less than the regulator's rating. Which is 75V | 15A in my case. (Panels connected in series of parallel will add Voltage or Amps)

So all is good.



(My confusion was rooted is assuming that the critical Amp value was calculated at the nominal 12V. Not so)

it is on the output side. There is another much lower current parameter on the input, but it is not represented in the victron type name. The numbers are maximum input voltage / maximum output current.

[hellosailor]

All conventional regulators are "dump" regulators. That is, any time the panels are putting out more than 14.4 volts (the exact voltage will vary) the panels literally DUMP the extra voltage. Either into a dump load, or burning it off as heat. Thrown out, goodbye, wasted.

An MPPT controller is a specialized type of PWM controller. It does not put out pure DC, the way a dump controller does. It puts out pulsed DC, like PWM controllers do. And actually, pulsed DC can be 10% more efficient than plain DC at charging the batteries, because it does not boil the electrolyte, does not cause constant microbubbles, does not drive up the internal resistance and actually slow down charging the way excess pure DC does.

But MPPT goes one step further. Since pulsed DC is basically a kind of AC power, the MPPT controller can adjust the pulses, put them through a transformer and capacitor, and instead of throwing out the excess voltage, they convert it ALL into exactly the right amount of voltage for the battery AND extra amperage. Think of it as an instant recycling program for that "wasted food" that the others throw out.

As a result the MPPT controllers gain about 10-15% over the PWM controllers, and over the plain dump controllers.

Some MPPT controllers actually do not use a "three stage" charge logic. Instead of doing the first bulk charge at 14.4 volts, they will look at your battery (they have to be programmed for it) and supply just 1/2 volt more than what your battery is actually at. All the rest of the power gets turned into amperage. As the battery voltage rises, every minute or so they readjust and again, supply just 1/2 volt more at the maximum amperage. This actually charges the batteries faster than plan "bulk, absorption, float" logic does.

So yes, MPPT (beware the counterfeits online) should gain you 10-15%, perhaps a little more. It may be cheaper to add another panel--if you've got room for it. It also means that you can recharge 10-15% faster, if there are gray skies or nightfall coming in.

[gauvins]

Thanks for your explanation. Very clear and helpful.

I've ordered online, where else? How to give out if it is counterfeit?

[hellosailor]

I haven't heard of any counterfeit MPPT controllers, but have heard that some controllers advertised as MPPT and sold online, simply are plain PWM chargers. You'd have to open them up, or observe exactly how they are charging, to find out if they are for real. I'd just stick to a reputable vendor, someone with solid reviews and praise online.