Hi guys, I am installing a new solar panel on my boat and I wish to know the difference between a pwm and a mppt controller.
Any other information would be most appreciated.thanks jm
MPPT is able to convert the excess voltage into amps.The more amps you produce the quicker the battery will charge.
Bigger the solar panel is the more gain is achieved by using mppt.
Good quality mppt is more expensive than pwm.
If you are only using the panel to keep the battery charged while the boat is not in use, pwm would be adequate.
Select to expand quoteseabird said..
MPPT is able to convert the excess voltage into amps.The more amps you produce the quicker the battery will charge.
Bigger the solar panel is the more gain is achieved by using mppt.
Good quality mppt is more expensive than pwm.
If you are only using the panel to keep the battery charged while the boat is not in use, pwm would be adequate.
Use a 24 volt panel with a MPPT controller, you will get more useful charging hours. Mine kicks in half an hour after daybreak and is still OK on a cloudy day. Or use 2 or more 12 volt panels in series. Chinese MPPT controllers seem to be OK and cost around $340.
MPPT solar controllers usually are PWM but not always vice versa.
To get the most power out of a given solar panel you need to give it the right load. For example an 80W solar panel connected directly onto a 12V battery might only produce a charge current of 2A (which power wise is 12x2=24W) because the solar panel is being forced to work at an output voltage of 12V. That particular solar panel might have a maximum power point of say 40V. If the solar panel is connected directly onto a 40V battery you get 40x2 = 80W. ie heaps more charging power. But because we dont have a 40V battery PWM electronics is used to reduce the 40V to an amount that produces the charge current we want for a 12V battery by at the same time boosting the charge current.
So get an MPPT unit. It will find the best load to put on the panel to get the most power out of it for a given amount of sunlight. Some of the really good ones can even charge a 12V battery in really dim light by stepping up say 6V from a solar panel to over 12V.
Theres a good Australian made MPPT one (from Seven Hills Sydney I think). But its not water or salt proof. My first one lasted a year and failed because of that. I got another one and put it in a good polycarbonate box. All good now.
My boat came with one of those cheap E Bay Chinese MPPT controllers fitted i the aft cabin and I had no idea how it worked so in comes Google surprise surprise someone had bought one dismantled it and provided a review:
It is very simple...MPPT, is overcharging cut off switch ,
simple, cheap and bulletproof, / internal voltage drop is 0.3 - 0.5 volts, negligible considering
-no load voltage is close to 20 volts/
PWM is pulse - width - modulation , bat. charger using some voltage from the panels
/ if excessive is available / and converts to get a bit more current for charging the bat.
Select to expand quoteWander66 said..
My boat came with one of those cheap E Bay Chinese MPPT controllers fitted i the aft cabin and I had no idea how it worked so in comes Google surprise surprise someone had bought one dismantled it and provided a review:
The review seems fairly positive and at least I know how to operate it now, mine has probably been there since 2009 does a good job charging the house battery with the 3 solar panels.
Well that's good mate. When you have figured out how to start your engine you will have some juice in the batteries to do it with. 
www.jaycar.com.au/12v-24v-30a-mppt-solar-charge-controller/p/MP3735
Bought mine off eBay a few years back still going strong
Select to expand quoteWander66 said..
My boat came with one of those cheap E Bay Chinese MPPT controllers fitted i the aft cabin and I had no idea how it worked so in comes Google surprise surprise someone had bought one dismantled it and provided a review:
The review seems fairly positive and at least I know how to operate it now, mine has probably been there since 2009 does a good job charging the house battery with the 3 solar panels.
Its good you got a good one of the Chinese ones. I bought 10 of one kind on Ebay because the specs were good, they were cheap and I thought I might sell them. The first one I tested didn't work, the next one didnt work and when I dissected the next one it wasn't MPPT, had no PWM system and could never have worked at all. I got done like a roast dinner. I buy a lot of stuff on Ebay from China and I think some sellers rely on making their junk so cheap no one is bothered chasing the refund for faulty products.
Thanks for the info gents .I have some more questions to ask but I will wait until I get some photos together of how it is wired up now .
Hi you can get a maximum power point tracking (mppt) solar regulator how it works is like a garden hose flowing then you put your finger over it and it puts pressure on the flow .The maximum power point tracking tracks the power in the battery and squeezes it out.Pulse width modulators (pwm) once the battery starts to fill with amps it starts to gently ease back and charge the battery in a gentler way thus increasing the life of the battery.I have a programmable pwm turns on at dusk of at dawn perfect for anchoring.All of the solar regulators are very easy to install most having diagrams on the regulators themselves, battery.regulator and lights.
When I am on the boat my solar panels goes directly to the batteries
/ chance to overcharge bat. is ZERO/ I don't wont any device reduce charge ,
if someone claims ..this device increase the charge defies the logic and law of physics .
when I am away small panel with cheap cut off switch charging all batteries
through Schottky diodes, simply If there is NO charge and I have for house
and start differen bat....they do not discharging each other.
Reasonably easy reading regarding the operation and benefits of an MPPT
www.solar-electric.com/learning-center/mppt-solar-charge-controllers.html/
Select to expand quoteTrek said..
Theres a good Australian made MPPT one (from Seven Hills Sydney I think). But its not water or salt proof. My first one lasted a year and failed because of that. I got another one and put it in a good polycarbonate box. All good now.
is it the GSL Electronics mob?
Select to expand quotefishmonkey said..
Trek said..
Theres a good Australian made MPPT one (from Seven Hills Sydney I think). But its not water or salt proof. My first one lasted a year and failed because of that. I got another one and put it in a good polycarbonate box. All good now.
is it the GSL Electronics mob?
Yes it is. Its a good design and works well but its totally exposed to the air. After my first one failed I bought another and put in an a polycarbonate box from Jaycar with decent water proof cable glands. The box was around $20 and the glands $3 each. Should have done that the first time 
Select to expand quoteTrek said..fishmonkey said.. Trek said..
Theres a good Australian made MPPT one (from Seven Hills Sydney I think). But its not water or salt proof. My first one lasted a year and failed because of that. I got another one and put it in a good polycarbonate box. All good now.
is it the GSL Electronics mob?
Yes it is. Its a good design and works well but its totally exposed to the air. After my first one failed I bought another and put in an a polycarbonate box from Jaycar with decent water proof cable glands. The box was around $20 and the glands $3 each. Should have done that the first time
so no drama with heat build-up in the sealed box?
Not so far. The box is a fair bit bigger than the GSL. Its outside feels very slightly warm sometimes but I don't mind that, it keeps it drier if moisture did get inside.
I bought a 10A Tracer MPPT a couple of years ago and am delighted with it. It was quite cheap ($100-ish iirc). It is a true MPPT (as proved by an A/B test showing 30% more current than the existing PWM regulator in slightly hazy sun). The remote display is great - shows house battery volts and regulator output.
Explaining MPPT to non-electrical people is quite hard. The best simple analogy I could come up with is the gearbox in your car - matching the revs to the road speed is sort of like matching panel volts to battery volts in the sense that it allows greater efficiency. If this sounds like gobbledegook, well at least I've done no harm, but some might find it useful.
Cheers, Graeme
This is the controller on my boat. Not sure what type it is. it mentions taper charger. Seems to work like on off switch
