How many solar panels does it take to charge a 150 AH battery?

If you’ve been planning to install an off-grid solar energy solution, it is an obvious thing one can ask: How many watts of solar panels do I need to charge a 150 AH battery? Or how much time it takes to 600 watts of the solar panels to charge a 150 AH battery full?

Solar Panels
150 Ah Solar Battery

In this article, we’ll explain the basic calculation of the solar panels’ capacity or wattage requirements to charge a battery bank.

First, let us calculate the battery watts. Inverter batteries come in 12 Volts capacity, let’s say you have a 150 AH battery bank then multiply the battery’s AH with its Volts to calculate the total battery wattages.

150 AH * 12 Volts = 1800 Watts

Battery AH * Battery Volts = Battery Watts

Second, in how many hours you want the battery bank to charge full using just solar panels. Let’s assume to charge a 150 AH battery full in just 4 hours. So divide the watts of battery by charging hours.

1800 Watts / 4 Hours = 450 Watts

Battery Watts / Charging Hours = Watts Required

So, we would require more than 450 watts of solar panels to charge a 150 AH battery around 4 hours under a clear and sunny sky.

But no inverter will charge the battery with such a high current.

A 150 AH battery rated with C10 will be charged with 15 (+1 or 2) Amps of current. Thus, for the battery’s long life you should not charge it more than that. Even an inverter won’t do that even if you supply more than the required current, rather the inverter moves those additional energies to direct output for day load.

Let’s adjust the formula little bit:

A 180 Watts of solar panel will generate around 8-9 Amps and 2 Panels in parallel will generate more than 15 Amps, which will be enough to charge an inverter battery. So assume we have a 2 * 180-watt panel.

1800 Watts / 360 Watts = 5 Hours (theoratical)

Battery Watts / Watts Required = Charging Hours

You just need 200+ Watts of solar panels to charge a 150 AH 12 V battery in 5+ sunny hours. This may take more than one and a half days to charge completely. So, in the end, just add 30% additional solar watts if you stick to a minimum, as there are some current losses in electricity conversion.

Smart Note: Better use MPPT (Maximum Power Point Tracking) solar charge controller over PWM (Pulse-Width Modulation) to extract the most from solar panels. Power losses are negligible in MPPT and over 97% efficient, whereas, PWM loses around 20 to 30% of its energy.

When we are talking about a clear and sunny sky, things are not bright always. Weather conditions like clouds, rains, and winter season also affect solar energy generation, we need to take such conditions into account as well.

If you’re relying completely on solar power, then add more watts of the solar capacity. This way you can rely on solar power in the day time and use the battery bank power at night time.

Related Posts

Published by Atul Kumar Pandey

Atul Kumar Pandey is a creator of atulhost. Being a business management graduate, he has a flair for business writing but also likes to dabble in technological trends. He is a voracious reader and an avid tech tester and loves to try new things.

    Comments and feedback

    • Hello Satheesh, you can charge 2 batteries at the same time while they are connected in parallel. Whenever we connect 2 batteries in parallel we achieve double ampere and same voltage. About charging with solar, yes it will be affected. Since the battery AH has increased to 300 AH (150 AH * 2) the charging time will be double, so the backup will be double.

      If you haven’t bought anything, I’ll recommend 24 volts setup, it will give you higher output.

  1. Hi, In how much time 320 watt solar panel can charge 150 Ah battery? Can you please suggest something as my battery is charging and discharging very quickly as per the inverter’s indicators and backup is very poor now 😔.

    • Hi Arpit, to charge a 150 Ah battery using 320 watt solar panel, it will take more than 6 hours. But only when you get clear sunlight and using MPPT charge controller. PWM based charge controller will take 10-20% more time. Also keep in mind that you cannot use 100% capacity of a lead-acid battery, it is meant to used up to 60-65%. For better backup, either increase the capacity of a battery bank or switch to a lithium-ion based battery.

    • You need a minimum of 300 Watt or more of solar panels for better charging. 100 Watt solar panel can charge a 150 AH battery but in an inefficient way to do so as it may take more than 20~30+ sun hours. If you increase the capacity by 200 Watt more you can charge the battery fully in a day or more to use it on regular basis.

  2. Please I have a solar panel of 12v450 watts connected in parallel and I’m charging a 150ah battery, should I use an MPPT or PWM charge controller.

    • Hello Prince, I’ll recommend you always use the MPPT charge controller. On small setups, MPPT shows better results. Use PWM charge controller only when there is no other better option available.

  3. Hi, I have a 150 ah battery and a luminous inverter. I want to buy a solar panel and a solar charge controller. Please suggest to me:

    1. Solar panel company, watts, volts (if I can’t find exact watts in a single panel I have to buy two pannel. So how to solve voltages problem i.e 12+12 volts = 24 volts…will that may cause problems to charge 150 ah 12v battery? Or this problem will solve by a solar controller? If so how many amps the solar controller must have).

    2. Solar control company and Amps.

    Badly need help. it’s urgent. Thanks.

    • Hi and thanks for sharing your query. Coming to your scenario, you said you have a 150 AH battery and an inverter. Since you said a battery, I’m assuming you are using a 12V setup. In that case, I’ll suggest you use a 12V solar setup. Max, you can go with 180 Watt solar panels and 2/3 panels are more than enough. About solar charge controllers, you can use any made-in-India controllers like AshaPower or LoomSolar. I’ll recommend using only MPPT charge controllers for small setups as they are more efficient and can give more power. These controllers come with multiple options in one like 12V and 24V configuration so upgrading to a higher one wouldn’t be difficult.

  4. Hello, I have two 320 Watts solar panel in series. Is it okay to my 12v battery 150AH? I’m using PWM solar controller. Please advice me.

    • Hello Raynold, it seems you have wrong configuration for just single 12V 150AH battery. 320 Watts solar panels are used for 24V setup although you can use it for single battery too if it allows you. But I’ll recommend you using parallel connection of solar panels that way you will get more AMPs. Please read solar charge control manual as well, it will guide you better.

Leave a reply

Required fields are asterisked and email address will not be shared.