SOLAR REGULATORS EXPLAINED! PWM versus MPPT – what’s best & why? PLUS upgrade your solar controller!

g'day guys and welcome back to another 12 
volt video now today i'm going to be talking   about solar regulators or solar controllers 
in particular the two most common types pwm   and mppt and in this video i'm going 
to be going through how they work   their differences and why one might be better than 
the other for your setup now a 12 volt solar panel   is generally putting out somewhere around 18 
to 20 volts which is why it's so important that   you need a regulator if you simply plugged your 
solar blanket or solar panel into your battery   it would work at first but then as the charging 
voltage climbs it'll eventually cook your battery   that's no good back in the day there wasn't 
much choice when it came to solar regulators   or solar controllers you basically had an 
on off switch so that when the sun was out   and your battery was discharged the switch 
would be on and it would charge up your battery   once your battery hit that high voltage 
point where it didn't need any more you'd   have to turn it off or it would turn off to stop 
cooking the battery now that wasn't particularly   efficient and it didn't charge the battery 
properly these days though you've got much   better options so let's see what you need for 
your setup to start with let's talk about pwm pwm stands for pulse width modulation 
and that's describing what this unit's   doing when it's charging your battery so to 
start with it pulses power into the battery   and it can actually change the amount of time or 
the length or width of that charge and that is   modulating so it's actually modulating the length 
of the pulse that might sound fairly technical so   let's take a look at a graph to make it easier to 
understand on the vertical axis of the graph it's   showing your voltage and on the horizontal axis 
is the time as you can see when the regulator   turns on it's at voltage then turns off for a 
short period of time before it turns on again   every time the regulator turns off it measures 
the voltage of the battery and adjusts for the   next pulse and you might have noticed that on 
this graph the charging voltage is 13 volts   that's because when you connect a pwm regulator 
to a solar panel and battery the large load of   the battery actually pulls the solar panel voltage 
down to just above the battery voltage they're not   able to actually boost that voltage any higher 
the voltage will simply increase as the battery   charges up then the regulator will output the 
higher voltage but shorten the width of each   pulse now let's talk about that in the real world 
so let's use this 200 watt solar blanket as an   example now i do have the exact specs but to make 
it easier let's assume it's putting out 20 volts   and 10 amps 20 volts times 10 amps is 200 watts 
once you connect this to your pwm regulator the   battery will pull that voltage down to around 13 
volts and because it's not actually able to boost   the output power you're now at 13 volts times 10 
amps for a total of 130 watts so your 200 watt   solar blanket is only able to put out 130 watts so 
as your battery is charging up and that internal   voltage does climb let's say it gets right up 
to 14.5 volts still getting 10 amps you're now   at 145 watts but unfortunately you're never going 
to get the full 200 watts out of a pwm regulator   so why would you want a pwm regulator well here's 
a list of pros and cons that might help you out   one massive advantage is their cost pwm regulators 
are fairly inexpensive which means you can get   into a solar setup without a massive entry cost 
secondly they're tested technology and they're   arguably more reliable and durable because they 
have much less complex technology inside now the   cons for a pwm regulator number one is that 
because they only charge at battery voltage   or just above it they're only around 70 percent 
efficient they can't boost the voltage or amperage   that's coming out of the unit secondly they 
can't use 24 volt solar panels so you can't take   advantage of a higher voltage for less voltage 
drop in your system these can only run with what's   called a 12 volt solar panel putting out around 
that 18 to 20 volt number finally they're not that   ideal for a larger solar system which doesn't 
matter too much if you're only talking about   camping or fall driving but you have to be mindful 
of it if you do ever want to grow your solar array let's get onto mppt regulators next now 
mppt stands for maximum power point tracking   but that's not all it does the first difference 
between an mppt and a pwm is where the pwm simply   connects the circuit and brings your solar panel 
output right down to your battery voltage and mppt   is two separate circuits so whatever's coming 
in is able to go through a computer and then be   outputted at a different level this is a more 
technically advanced system which means it's going   to charge your batteries much better now let's use 
the same example as before with a 200 watt panel   and take a look at a graph of an mppt regulator 
hypothetically let's say we've got 200 watts   that's going into the input side of your mppt 
regulator or controller if your battery needs 13   volts to charge the mppt will take that 200 watts 
divided by the 13 volt output that's required   and then output the same amount of power minus 
a tiny inefficiency as what it's receiving   so it'll put out 13 volts but at around 15 amps 
so as well as actually taking advantage of the   entire amount of power that's coming out of your 
solar panel and mppt has another advantage as well   and that is in the name maximum power point 
tracking so as an example let's say that   the maximum power point of this solar panel sits 
around here on this graph as a cloud passes over   it's going to drop the output considerably but 
the mppt regulator is able to constantly track   scanning for that maximum power point and output 
it a pwm can't do that it's simply a passive   system and what this means is that as the solar 
panel heats up or loses efficiency clouds pass   over or you might have a tiny bit of partial shade 
on your panel the mppt is always able to make the   most of it and output the maximum power so let's 
talk the pros and cons of an mppt regulator and   why you might want one well first of all 
they're much more efficient than a pwm regulator   secondly they're more able to use the entire 
output of your solar panel because they're   not just passively dropping the voltage to your 
battery voltage and then using as much current   as they can these are able to actually boost 
up that current to use the entire panel output   thirdly because they can track that maximum power 
point even in low light cloudy conditions or as   the panel heats up they're able to put out more 
power more efficiently than a pwm and last because   they're able to actually input a larger voltage 
you're not restricted to using 12 volt nominal   solar panels so you could use a higher voltage 
solar panel for less voltage drop in your system   which equals more power getting into your 
batteries now the cons of an mppt regulator number   one they're generally a bit bigger and heavier 
than a pwm of the same capacity but it's not   usually a big deal number two because they're more 
advanced inside they're generally more expensive it's all well and good to talk about the 
differences of these regulators on the bench   but what's much more important is to see their 
actual real load performance so let's take them   outside and compare them both batteries are 
discharged to around 12.7 volts or about 75   capacity and they've been sitting overnight we're 
using the same solar blanket both laying flat on   the ground which isn't ideal but it's a good 
comparison connecting both panels up the pwm   instantly connects the circuit while the mppt 
calculates that maximum power point after about   30 minutes in the sun you can see that the battery 
voltage is already climbing the panels are heating   up there's voltage drop in the system and it's not 
a perfectly bright day so we're not at full power   the pwm is putting in around 3 amps or 40 watts 
of charge while the mppt is taking advantage of   the extra power and charging it over 7 amps or 
just over 100 watts so in summary the mppt is   putting out more than double the power of the pwm 
the losses in the system the fact that it's not a   perfectly bright day and the heat of the panels 
mean that we're not getting a full 200 watts   but you can see that in the real world that's 
where the mppt makes such a massive difference   so if you want a simple inexpensive option 
that's going to work in most situations   then you can't go past a pwm however if you want 
to make the most of the entire amount of power   that your panel's able to put out and ensure that 
your battery is getting the highest charge it can   you'll need to step up to an mppt now this 
is a fairly shallow look at what is a very   in-depth topic so if you do have any questions 
make sure you throw them in the comments below   if you enjoyed this video make sure you 
hit like and remember to hit subscribe   and the notification bell so you don't miss 
our next one finally thanks for watching you

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