Connecting MPPT with Solar Inverter

The small discussion presented in this article explains whether or not it is advisable to Connect parallel MPPTs with Solar inverters for increasing the net current value of the MPPTs.

The question was raised by Mr. Ahmed Qaid

Want to Convert Home Inverter to Solar

I have many questions and I hope you to answer them because I'm really in need of your advice

1) If I want to convert any inverter into solar, many products are available in Indian market:
a) SU-KAM solarcon
b) Luminous solar retrofit charge controller
c) Amberroot REhub PWM
which one is better for an inverter of 12V battery system?

2) my friend bought Amberroot REhub MPPT and he has an inverter with 24v battery system this solar charge controller charges the battery with 15 amp but if he wants to add 24 batteries in parallel to the system the charging current must increase too so can he use mppt solar charge controller with 400wp to get another 15 amp to make the charging current upto 30 amp? and Is it safe for the system?

3) I'm planning to buy an air cooler, all I know is that ---- is a good company in air conditioners field but in air cooler I don't have any idea, I searched ----- website and I think their products are overpriced so which company is good in air cooler?

MPPT will only Convert Excess Volt to Current

My Reply:

The dealer will know better about those products than me, so it's better to consult them.

2) An MPPT circuit will only convert the excess voltage from the panel to an equivalent amount of current if the load operating voltage is lower than the panel output voltage....MPPT will never manufacture current by short the V x I of the MPPT at any instant can never exceed the Panel's V x I value.

so you can measure the existing MPPT output and check it as per the above fact...if it agrees with it then no additional MPPT would be required neither would it work.

If you find the V x I of the MPPT is much lower than the solar panel's V x I during the given instant, then you may think of replacing the "Amberroot" with some other higher rated MPPT, or you can connect another MPPT in parallel

I can only discus about electronic concepts, I'll never want to recommend or endorse a particular product.

More on MPPT Converters:

Unlike solar trackers, MPPT function may be limited only to ensure that the recommended wattage from the panel is fully delivered to the load without losses.

This limitation becomes true because the MPPTs have access only to the solar panel's output, and not the sun rays, therefore whatever processing and optimization it may do is limited upto the solar panel specs.

On the contrary solar trackers are much efficient since they are able to track the sunlight at every instant and make sure that every bit from the sunlight is delivered to the load.

Having said this, a solar tracker may be helpless and waste precious power if the load is not correctly matched with the panel's, specs.

For example if the panel voltage is 24V then the load voltage must be close to this value, may be at around 20V, otherwise there could significant losses and the tracker efficiency may get seriously hampered, and the purpose of the solar tracker may fail.

A better idea is always to use an MPPT in conjunction with a solar tracker, which produces a double impact and makes sure that the high tracking efficiency of the solar tracker is met with the high processing efficiency of the MPPT and these together could finally help to achieve the most favorable response from the available sunlight.

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Akinbi Oluwadamilare said…
Helo sir,am having issue with my Solar charge controller.
I noticed that the controller am using(though pwm) is under charging my inverter battery (float charge at 13.7v maximum) and when i use solar to charge directly without controler and the charging reach up to 14v,it stays longer before it discharges compare to 13.7v.
And as a result of this.
I want you to give me a circuit diagram that can address the charging issue.
Also I want to know the float charging voltage for every battery of 12v DC.
Swag said…
Akini, you can remove the charger and use a 14V fix regulator to charge your battery, no need of any auto cut-off circuit. You can specify the Ah value of your battery, I'll try to figure out an appropriately rated 14V regulator design
Akinbi Oluwadamilare said…
Which 14v fixed regulator can i use and
can I get an mppt circuit from you?
Swag said…
please provide the battery AH spec, I may try to find it for you.
Akinbi Oluwadamilare said…
My battery is 100amps deep cycle battery...
Akinbi Oluwadamilare said…
Please sir,how can I configure SG3524 as a solar charge controller in a circuit that can trip off voltage at 14v with the help of a relay?
Swag said…
SG3524 is an oscillator IC, it cannot be used as cut off circuit for batteries.
Swag said…
You can try the following simple concept, this will charge your battery as long as it does not reach 14V or 14.4v and shunt the supply by grounding the excess power.
Akinbi Oluwadamilare said…
Sir which IC can I used to cutoff voltage for solar charge controller?
Or which circuit can u recommend for me?
Swag said…
Most of the battery charger circuits presented in this website are auto cut off type, please check the battery charger category to get the full list of those.

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