MPPT on small solar panels, an interesting concept The MingHe MPPT solar charge controller

[rin67630]

I have already explained a couple of times here, why one should NOT use an MPPT controller between a nominal 12V solar panel (Voc~17-18V) and a 12V battery.

MPPT controllers need a good voltage difference to be able to find the right MPPT value under all weather conditions.
Nominal 12V solar panels are optimized to be used with 12 V batteries with a PWM controller, not an MPPT controller.

Now what could you do if you have to start with a nominal 12V solar panel and want to get all the advantages of MPPT operation?
You basically have two solutions:

a: Use a 6V battery (or a 7,2V one) That solution works quite well if your MPPT controller can be adjusted to that battery voltage.
b: Use a 24V or higher voltage battery, together with a boosting MPPT solar controller.

A boosting MPPT solar controller ???

Yes, boosting MPPT solar controllers exist and will permit you to charge 24V or 36V batteries or even higher (like what you have in e Bikes) from a single 12V 100W panel, and they do it quite well !
Counter-intuitively, in the world of DC-DC converters, boosting converters are the most efficient ones, easily reaching 98% where a voltage reducing buck converter will do hard to get better than 92%.

An example of a boosting MPPT solar controller is the MingHe Solar Charge controller.
Boosting MPPT
Okay, it is a cheap Chinese stuff, but I know the company, it is the company behind the JUNTEK and the DROK DC-DC converter which I have been using and I know they are doing seriously engineered products.

That is surely worth to give a try...

 

[Atomic Ed]

I have already explained a couple of times here, why one should NOT use an MPPT controller between a nominal 12V solar panel (Voc~17-18V) and a 12V battery.

MPPT controllers need a good voltage difference to be able to find the right MPPT value under all weather conditions.
Nominal 12V solar panels are optimized to be used with 12 V batteries with a PWM controller, not an MPPT controller.

Now what could you do if you have to start with a nominal 12V solar panel and want to get all the advantages of MPPT operation?
You basically have two solutions:

a: Use a 6V battery (or a 7,2V one) That solution works quite well if your MPPT controller can be adjusted to that battery voltage.
b: Use a 24V or higher voltage battery, together with a boosting MPPT solar controller.

A boosting MPPT solar controller ???

Yes, boosting MPPT solar controllers exist and will permit you to charge 24V or 36V batteries or even higher (like what you have in e Bikes) from a single 12V 100W panel, and they do it quite well !
Counter-intuitively, in the world of DC-DC converters, boosting converters are the most efficient ones, easily reaching 98% where a voltage reducing buck converter will do hard to get better than 92%.

An example of a boosting MPPT solar controller is the MingHe Solar Charge controller.
Boosting MPPT
Okay, it is a cheap Chinese stuff, but I know the company, it is the company behind the JUNTEK and the DROK DC-DC converter which I have been using and I know they are doing seriously engineered products.

That is surely worth to give a try...

Maybe this is a silly question but forgive me I am new to solar. If you have what you say 12v panels but put them in series string to increase voltage much higher then why does it make a difference if their are 17 or 18v individually?

I'm trying to learn all I can right now and I zm actually now putting together an mppt based system using 17v vmp panels but should be somewhere around 121v in series.

 

[rin67630]

Maybe this is a silly question but forgive me I am new to solar. If you have what you say 12v panels but put them in series string to increase voltage much higher then why does it make a difference if their are 17 or 18v individually?

I'm trying to learn all I can right now and I zm actually now putting together an mppt based system using 17v vmp panels but should be somewhere around 121v in series.

You are fully right. If you put together several 17Vmp panels in series (and they are irradiated similarly), its equivalent to a panel with multiple Vmp voltage.
Then you can use any MPPT controller (in your case one withstanding 150V input) to feed a 12V battery.
You were probably be better off building 2 strings series / parallel to get 60V input, the MPPT controllers withstanding 75V input are cheaper.
Then you could also orient the 2 strings south-east and south-west, which would give you a flatter day curve, that is nicer to the battery.

I was speaking of low-power solutions with a single e.g. 100W panel that is usually 12V nominal.

 

[Atomic Ed]

thanks for the reply. Just trying to learn all I can and there seems to be so many variables with solar that its confusing at times. Experts like yourself, clearly explaining things and reassuring what we believe to be the case is extremely helpful to us new to it all.

Thanks again for your help.