ghostlymoron
Well-Known Member
I'd go for as much solar as possible against sweating the assets of two panel. I've always been happy with PWM controllers. You can always upgrade to a MPPT controller at a later date.
Solar set up
- Thread starter stu9000
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Kelpie
Well-Known Member
Just watched a very persuasive video about PWM vs MPPT. Makes the advantages of MPPT looks like very little for a great deal of money.
MPPT seems to make the most sense when you have run out of space for more panels, or where your panels are remotely located and you want to wire them in series for higher voltage and lower losses.
The only charge controller I have owned yet was an unbranded PWM from eBay. Nearly five years on, and it hasn't let me down. It's very tempting to buy a bigger version of the same thing for my new setup- 60A for a tenner, seems too good to be true!
Baggywrinkle
Well-Known Member
The real advantage of MPPT comes from less than ideal conditions and bigger arrays. There are situations, as demonstrated by the video where there isn't much in it, especially when it's a small array, the panels are not at extremes of temperature, the battery is almost full and the sun is out. Introduce an overcast sky or poor weather and MPPT will harvest more power from the panels than PWM and as this is generally a percentage more, the bigger the array, the more difference it makes.
For simple battery charging at a mooring with a small array 50-100W then PWM will be a good cost-effective solution.
If you've got the time and inclination the differences are explained here ....
MPPT vs PWM Solar Charge Controllers
or here ....
Which solar charge controller: PWM or MPPT? | Victron Energy
Ultimately it's a question of budget and requirements.
I've got 300W in series on a Bimini (no shading) and a Victron MPPT in the Med and it gives me more than enough to be self-sufficient including a 24hr fridge - IMO if looking for energy independence (no shore power, wind, generator, or motor needed) then the basic 12v AWB with fridge needs around 300W to be able to forget about battery state (in the med). One of my panels failed and took me down to 200W and I was struggling.
I find any claim that PWM will generate the same amount of power as MPPT simply misleading, especially when all the variables start to change due to weather, battery state etc. and the array size starts to creep up above 200W
If PWM was that good, MPPT would not have a market.
IMO - for 50-100W to keep the battery topped up when not in use - PWM is fine, for off-grid living with no other source of charging and 300W and over, MPPT every time.
For simple battery charging at a mooring with a small array 50-100W then PWM will be a good cost-effective solution.
If you've got the time and inclination the differences are explained here ....
MPPT vs PWM Solar Charge Controllers
or here ....
Which solar charge controller: PWM or MPPT? | Victron Energy
Ultimately it's a question of budget and requirements.
I've got 300W in series on a Bimini (no shading) and a Victron MPPT in the Med and it gives me more than enough to be self-sufficient including a 24hr fridge - IMO if looking for energy independence (no shore power, wind, generator, or motor needed) then the basic 12v AWB with fridge needs around 300W to be able to forget about battery state (in the med). One of my panels failed and took me down to 200W and I was struggling.
I find any claim that PWM will generate the same amount of power as MPPT simply misleading, especially when all the variables start to change due to weather, battery state etc. and the array size starts to creep up above 200W
If PWM was that good, MPPT would not have a market.
IMO - for 50-100W to keep the battery topped up when not in use - PWM is fine, for off-grid living with no other source of charging and 300W and over, MPPT every time.
Pete7
Well-Known Member
For 12v panels I would agree. However, for those 300w panels you are thinking about the voltage is more like 33v which the MPPT can then convert down to increase the current. The one other thing the Victron MPPT does with the battery voltage and temperature widget, is raise the absorption voltage. My batteries are currently being charged with a 15.01v because the water temperature and therefore the batteries is 8c in the Solent.
