My current solar system for home:
1. 12V 100W polycrystalline Solar Panel.
2. 12V 75Ah Lead Acid solar tubular Battery.
3. PWM 12V 10A Solar Charge Controller.
4. 12V Input and 200VA Output Inverter.

Current Problem:
Battery not getting charged fully daily because solar panel is getting around 3-4hours sunlight and that too includes sunlight at non-90 degree conditions.

So, I want to add an additional solar panel[preferably 200W or more] which will get 90 degree sunlight from 1pm to 5pm. Also, we get around 50 minutes of on grid supply. During this time inverter charges the battery too.

My questions as per my whole day research:

  1. If I add a 24V 200+W solar panel, I have to connect the panels in series because
    parallel means same voltage but ampere gets added.
    series means same ampere but voltage gets added.
    In this cases what changes are needed to charge the 12V battery?
    I guess someone will suggest MPPT controller. What is the best controller available in India? budget max6000INR

  2. To avoid huge costs and hastle for the above requirement if I go with 12V 150W panel, then I will just need to connect my 12V 10A with a new 12V 20A controller in parallel to draw 8.6+12.5A=22A approx. current from solar panels.Am I correct here?

  3. During a hot and shiny summer how much watts does a 100W panel produce in 90 degree sun conditions? What is the worst output that I will get in rainy season?

  4. While charging battery from the inverter during grid supply, I see the inverter shows around 6A-9A current supply to the battery. Is it the current only that counts how fast the battery goings to be charged. Does change in voltage play any role?

  5. I want to pull as much current as possible from grid and put it to my battery during that 50min time. What device will let me do so? Logically to charge a 12V 75Ah battery from 0-100 we will need something that putts 900W of power into the battery in an hour.
    900/12=70A approx. How much Ampere is safe for longetivity of battery?

P.S: In any circumstances safety and device efficiency is my priority.Please excuse any non-sensical thing if I mentioned above.

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Hello dear,
First of all I would like to know in which region you are living.
If you have 3 hours of sunlight then you must add extra 2 panels of 100W in parallel.
1) you can’t add it in series because it will increases voltoage to 24 V which may damage your charge controller or battery. So connect new panels in series. And you need to buy charge controller of 12V/20 AA which will not cost more than 2500.
2) Panels connected should be of same ratings. Your previous panel is of 100 W. So you must buy panels if same rating.
3) In peak condition, 100 W panel will gives you approx. 62.5 W/hour if you are using PWM controller. &
Gives 85W /hour if you are using MPPT charge controller.
If no sunlight, no energy will produce.
4) yes. Current plays all role. Increasing voltage beyond limit may damage your battery

Thank you,
Sagar Kudale

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