The importance of regulator on solar efficiency

[john61ct]

Real ones have heavy heatsinks.

[Quincofish]

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)

Have a read http://www.blueskyenergyinc.com/uplo...cal_Sailor.pdf

Worked very well on my last sailboat..

[CatNewBee]

Originally Posted by 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.

Well, that is a very unscientific explanation. The truth is something different.

First of all, a solar panel can be considered a current source, not a voltage source, that said with rising radiation the current rises somehow proportionally while the voltage stays almost constant. The inner resistance of a battery is usually much lower then the inner resistance of a solar panel or even a grid of panels. So if you connect a battery, that is not full yet, to a solar panel directly, the voltage of the panel will drop to the voltage of the battery and the panel will yeld all current that is produced at the moment with this voltage in the voltage/ current diagram. If the Vmp is relatively close to the Absorption voltage of the battery chosen (+2...3V), then the panel operates almost at its peak capabilities and there is no energy loss at all. You can easily shortcut a solar panel and measure the Isc, the current is always between 0A at Voc (open circuit) and Isc at V=0V (short cut), the power output is V*I between this two ends and has a maximum at Vmp * Imp.

That is exactly what PWM controller do. They connect the panels directly to the battery and yeld the maximum amps of the panel at a given battery voltage. Due to heat, panel voltage and current degrades, that is the reason for having 2-3V higher Vmp on the panels. A PWM controller would beat in normal conditions (sun shine, hot weather) with the right panels chosen any MPPT.

The pulsing starts at the point, when the battery voltage climbs over the Absorption set point. Then the PWM controller turns the solar off and on to reduce the current output. A MPPT controller would also start to waste energy at that point, otherwise the battery would start boiling.

So why pay more for an MPPT then?

First of all, you can use any panel with an MPPT, as long as the voltage is much higher than the battery voltage, then the solar current to the controller will be much lower and you can use smaller cabling, additionally you may have advantages in partial shading, where the bypass diodes short shaded strings and use the other cells with full amps on a lower voltage set point. This is something an MPPT can handle well, itsearches always for the maximum possible power output between battery voltage and Voc of the solar strings connected.

This comes with a tradeoff of course. The MPPT controller must transform incomming variable voltages and currents to the voltage of the battery and there are some losses by heat during the transformation ( reason for the heat sinks ). This energy is really burned.

However, MPPT controller have advangages in cloudy conditions and shading and outperform in the long run the PWM controller by 5...15%, but also cost at least double as the PWM.

[travellerw]

Originally Posted by gauvins

Thanks for your explanation. Very clear and helpful.

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

The "counterfeit" ones are usually sold on Ebay. Quite easy to spot as they are sold at much lower prices than other MPPT controllers.

IMHO, just stick with Victron (or another recognized brand like Genasun, Midnite, Morningstar, ect). We have had a couple of different brands of Chinese MPPT controllers on our boat in the last 3 years. Although they were fine, the Victron's are just a better product. Better built, better support, better service and better features. Personally, I think they are worth the extra money over Chinese controllers.

[thomm225]

Originally Posted by travellerw

The "counterfeit" ones are usually sold on Ebay. Quite easy to spot as they are sold at much lower prices than other MPPT controllers.

I think they are worth the extra money over Chinese controllers.

I used one of those $12.00 PWM Chinese Controllers for about 4 years. It held the voltage at 14.4 after charge up.

Mine was hooked up with alligator clips so I would unplug it after the voltage on the panel side reach 18-19 volts

I later bought a Windy Nations PWM Controller with float setting that failed in less than a year due to moisture with the freezing cold weather this past winter. I still have two of the Chinese Controllers and they still work

They use LED's to indicate level of charge but the rest (the batteries true SOC) you probably need to verify with a meter

[travellerw]

Originally Posted by thomm225

I used one of those $12.00 PWM Chinese Controllers for about 4 years. It held the voltage at 14.4 after charge up.

Mine was hooked up with alligator clips so I would unplug it after the voltage on the panel side reach 18-19 volts

I later bought a Windy Nations PWM Controller with float setting that failed in less than a year due to moisture with the freezing cold weather this past winter. I still have two of the Chinese Controllers and they still work

They use LED's to indicate level of charge but the rest (the batteries true SOC) you probably need to verify with a meter

We were talking about MPPT controllers. PWM controllers are completely different. Yes there are cheap PWM controllers that work. Hell there are cheap MPPT controllers that work (I have had 2)... However, I will say again. The Victron controllers are hands down better, for the reasons I listed above.

Its just my opinion after 3 years of full time use. I have no affiliation with Victron.

[thomm225]

Originally Posted by travellerw

We were talking about MPPT controllers. PWM controllers are completely different. Yes there are cheap PWM controllers that work. Hell there are cheap MPPT controllers that work (I have had 2)... However, I will say again. The Victron controllers are hands down better, for the reasons I listed above.

Its just my opinion after 3 years of full time use. I have no affiliation with Victron.

Yeah, I was just pointing out the alternative especially for those that aren't living aboard with refrigeration etc and don't need so much power

I have 85 watts of solar (65 and 20 watt panels in parallel) hooked up now to a PWM Controller I bought for $18.00. I have the float set at 13.7 volts. So far so good with this one.

None of my solar is mounted either so sometimes the 20 watt panel is stored in the lazarette locker while underway. The larger 65 watt panel is on the aft lazarette locker cover and secure with some leach line

https://www.amazon.com/dp/B01MU0WMGT...a-584565296832