MPPT What do they actually do

[frygood]

Hi all

 

AS the title could somebody please tell me what a MPPT actually do.

in layman terms please.

 

Thanks in advance.

 

 

[cuthound]

They ensure that the maximum amount of solar energy is converted into electrical energy by wasting less energy in the regulating process.

[WotEver]

To expand slightly...

 

A panel will at any one time have a 'sweet spot' voltage where it is generating the maximum power that it can. This voltage varies according to the heat of the panel and the amount of sunlight it's receiving. An MPPT controller varies the panel's voltage (by varying the load) to track that 'Maximum Power Point'

[Justme]

They isolate the input from the output so that as above the panel can run at its sweet spot.

 

Whilst a PWM chops the power/voltage in to match the voltage out.

They also allow you to have a much higher array voltage which means you can use thinner cable from the array to the controller.

[nicknorman]

They do 2 things really. One is to convert power from one voltage to another in an efficient way. The first voltage being the panel voltage, the second voltage being whatever is needed to charge the batteries. So as you may know, power = volts x amps. Or rearranging that, amps = power/volts. So bearing in mind power is (roughly) the same going into the MPPT as coming out, if the battery voltage is lower than the panel voltage, the current going into the batteries is more than the current coming out of the panels. So the MPPT can step down the voltage and step up the current.

 

Secondly, the panels will have a certain voltage at which they produce maximum power. In other words, if you vary the load and hence the voltage from the panels, there will be a point where the panels are producing maximum power. More voltage gives less power, less voltage gives less power. The trouble is that this maximum power voltage varies according to conditions (amount of sun, temperature). So the MPPT varies the voltage from the panels (by varying the load) and measures the power (being volts x amps) and settles on the load/voltage where the power is maximised. It keeps "sniffing" around this point, adjusting the load so as to maintain maximum power as conditions change.

 

Well maybe that wasn't in layman's terms but it is hard to explain simplistically though hopefully someone else will be better at it than me!

[cereal tiller]

They isolate the input from the output so that as above the panel can run at its sweet spot.

 

Whilst a PWM chops the power/voltage in to match the voltage out.

They also allow you to have a much higher array voltage which means you can use thinner cable from the array to the controller.

Thinner cable is one advantage

 

Another is that MPPT will go into Float Mode,PWM controllers generally do not

 

CT

[nicknorman]

Thinner cable is one advantage

 

Another is that MPPT will go into Float Mode,PWM controllers generally do not

 

CT

?? Well the two I have experience of do go into float mode.

[cereal tiller]

?? Well the two I have experience of do go into float mode.

The ones I have don't,can only be set manually by adjusting input voltage

 

CT

[matty40s]

Err, yes, those answers pretty much nail it.

Well worth the extra expense if you want a large array.

[nicknorman]

The ones I have don't,can only be set manually by adjusting input voltage

 

CT

This is the data sheet on the one I have in my caravan: http://www.bimblesolar.com/docs/epsolar-LS1024BP.pdf

 

You'll note that it has float mode.

[tree monkey]

Magic, just accept its magic

[Dalslandia]

Very good information guys, thanks.

[frygood]

HI guys

 

I have a Victron MPPT 75/15 which has a green flashing light on it.

I also have a colour controller i can see the PV power box on the controller but it always shows 0w

When i go into the devise list i can see the Mppt on the list click on that and various lists come up one of which is the state which says Off

So how do i turn it on?

Looking at the MPPT there is no cables in the Load terminals i`m not sure if this is correct.

 

Any ideas Guys

[matty40s]

Load terminal is designed for street lighting and other uses. You could rig up a timed night light from it, or similar, but most people do not use it.

[nicknorman]

HI guys

 

I have a Victron MPPT 75/15 which has a green flashing light on it.

I also have a colour controller i can see the PV power box on the controller but it always shows 0w

When i go into the devise list i can see the Mppt on the list click on that and various lists come up one of which is the state which says Off

So how do i turn it on?

Looking at the MPPT there is no cables in the Load terminals i`m not sure if this is correct.

 

Any ideas Guys

 

Can't help you with how to turn it on (not without going away to read the instructions anyway) but it is normal to have nothing connected to the load terminals.