This post is a part 2 of my discussion about MPPT and solar charge controller with my Friend (SekteCinta). On part 1 we discuss about what is MPPT and why it’s exist but haven’t discuss about MPPT in battery charge controller.
SC: I still confuse about battery charger and MPPT
M: So, There is no direct connection between Battery charging voltage with MPPT.
SC: So, the relation between battery charge and MPPT is what confusing me. Here’s the quotation got from here:
“MPPT or Maximum Power Point Tracking is algorithm that included in charge controllers used for extracting maximum available power from PV module under certain conditions. The voltage at which PV module can produce maximum power is called ‘maximum power point’ (or peak power voltage).“
M: There is a battery charger beside an MPPT in charge controller. So you can imagine there is two block inside a charge controller,
1. MPPT
2. Charger Battery
SC:”The major principle of MPPT is to extract the maximum available power from PV module by making them operate at the most efficient voltage (maximum power point). That is to say:
MPPT checks output of PV module, compares it to battery voltage then fixes what is the best power that PV module can produce to charge the battery and converts it to the best voltage to get maximum current into battery. It can also supply power to a DC load, which is connected directly to the battery.“
From the quotation, I bolted the sentence which confuse me. Can you explain this?
M: Haaa. If you already understand MPPT, then there is another thing about MPPT we haven’t discuss and need to understand.
SC: OK OK, I already understand about MPPT.
M: Because now we can “control” PV power output by variating the PWM in Transistor
SC: And?
M: As a lot people already know electricity is consumed immediately after it’s produce. While we know the problem with electric storage (in this case battery) is it’s power storage rate are limited. So if the output produced by MPPT can’t consumed or absorb by the battery, why should MPPT acquired maximum power from the PV right?
SC: What? I still don’t understand………
M: Oooops, Please elaborate which part you haven’t understand?
SC: So if the power output produced by MPPT can’t stored by battery, why should MPPT acquire maximum power from PV right?
M: Yes!
SC: Isn’t MPPT always used or MPPT algorithm always running right?
M: Well to run correctly, MPPT need load. in our previous discussion we used Variable Resistor instead of Battery.
SC: So a Load to calculate algorithm MPPT only variable resistor right?
M: Well, if we only use variable resistor or transistor, Energy produced by PV will dissipated into heat in Transistor or Resistor. So, in reality, the load not only Transistor but Transistor series with Battery Charger.
This Battery Charger can be form by DC-DC Converter such as buck boost converter, depend on the specification needed by connected battery.
Hope you Understand.
SC: Hmmm, I start understand, Wait a minute I will read it again. But I forget how to read buck boost converter circuit!
M: For now, we don’t need to understand buck boost converter circuit.
What we need to understand is if output voltage or current from MPPT can matched with buck boost converter, then buck boost converter don’t need to work hard. If buck boost converter not working hardly, higher efficiency can be reach.
That’s it our discussion about MPPT and it’s relation with battery charger.
I know there is still some consistency in mentioning some name, peripheral and term. any correction is needed from you.
Hope you learn new thing from what i write