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

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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.

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22 responses to “How many solar panels does it take to charge a 150 AH battery?”

  1. Satheesh Avatar

    Can I charge 2*12 Volts 150 AH battery (two batteries same time use) with 12 Volts and 540 Watts solar panel?

    1. Atul Kumar Pandey Avatar

      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.

  2. Arpit Avatar

    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 😔.

    1. Atul Kumar Pandey Avatar

      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.

  3. AGBORTABOT Avatar

    Hello am from Africa,I have just 100watt panel to change 150ah battery can it be possible?

    1. Atul Kumar Pandey Avatar

      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.

  4. Prince Michael Avatar
    Prince Michael

    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.

    1. Atul Kumar Pandey Avatar

      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.

  5. Th GUIBAMANG Avatar

    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.

    1. Atul Kumar Pandey Avatar

      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.

  6. Raynold Avatar

    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.

    1. Atul Kumar Pandey Avatar

      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.

  7. Soleh Laharwal Avatar
    Soleh Laharwal

    I have a 1/1/2yrs old Exide Invatubular 12v battery and I want to connect it to the solar panel.

    1. How many panels are required with wattage.
    2. Which solar controller is best?
    3. MPPT or any other?

    Please suggest the best panels available in India. Mostly made in India.

    I am from Srinagar JK.

    1. Atul Kumar Pandey Avatar

      Hi Soleh Laharwal, first make sure what is the maximum load in your house and how many wattages you use in a day. Just get a little bigger capacity panel. Since you are using a single 12V battery you cannot connect 24V solar panels (bigger panels are only possible with 24V) to it unless the charge controller supports it. So first choose a solar charge controller (MPPT > PWM, but the cost of MPPT is high) based on your load demand then pick solar panels 20-30% extra to your whole demand.

      Extra note: Please chose Monocrystalline solar panels as they can generate more energy in cold locations. Some known brands are LoomSolar, Luminous, TATA, VikramSolar, and Exide.

  8. Hillary Avatar

    Hello, can you please advice on the system I can get for my 100ah deep cycle battery for better usage. Solar panel, charge controller, and inverter size, I am in East Africa.

    1. Atul Kumar Pandey Avatar

      You can go with what is best available in your country. Choose MPPT charge controller, and solar capacity based on the load and voltage setup you have (12V max 400-600 Watts and for 24V max 600-1000 Watts). Please read out other articles on solar.

  9. Nagendra Kumar Avatar
    Nagendra Kumar

    Hi, plz suggest me, I have 2 solar panels 150+160W both are connected in parallel to 150Ah 12V battery there are no any type of using charger controller, can you plz tell me that it is good connection for battery or solar panels because inverter also connected on same battery. I am using same configuration last 4 year with higher backup, one think’s are always run in my mind that the solar panels does not damaged?

    1. AtulHost Avatar

      Hello Nagendra Kumar, thanks for raising your query. It seems you are using solar setup without a charge controller, and your inverter is also a normal one (non-solar inverter). In that case always use a charge controller. You can damage your panels, battery, and even inverter. A charge controller is always needed to protect your battery from overcharge.

  10. Raj Avatar

    I have 160 ah luminous battery.
    How many solar plates I needed to charge this battery with 50 watt 2 fans also run during daylight

    1. AtulHost Avatar

      Hello Raj, keep in mind that in 12V system 600~800 watts is the limit anything over than this is not useful. Battery only needs 400~500 watts solar panels to charge itself rest you need to plan yourself with 30-40% additional load capacity. I myself running a 12V inverter with 600 watts solar setup and everything is running smooth for me. My day load is handled by solar and it is able to charge for little night backup so I can survive.

  11. Shadrack Mutinda Avatar
    Shadrack Mutinda

    Hello, can 200 Watts solar panels charge 150 AH full enough?

    1. AtulHost Avatar

      It will, but the setup will take more time to charge a 150 AH battery full.

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