# 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 for 600 watts of the solar panels to charge a 150 AH battery full?

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 wattage.

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 a 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 2 Nos * 180 watts solar panels.

1800 Watts / 360 Watts = 5 Hours (theoretical)

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.

Critical 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 (calculate house load and match that load by solar panels). This way you can rely on solar power in the daytime and use the battery bank power at nighttime.

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### Responses to “How Many Solar Panels Does It Take To Charge a 150 AH Battery?”

1. Satheesh

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

1. 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

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. 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

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

1. 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. Muhammed Aliyu

Please sir, can I used 2 solar panels 24v/ 200w to charge two 100ah of battery connected series.
Can I get productive results and many hours can make complete charging.

1. Yes, but use decent charge controller and connect solar panels accordingly as some controllers require just parallel connection and some can handle series of multiple panels. About results, 400 watts is enough for just battery charging and very small running load. If the load is high then install more panels, otherwise it is okay for very small load.

4. 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. 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

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. 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

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. 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

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. 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

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. 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

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. 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

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. 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.

1. Uwem

Hello Sir. I just bought 3 units of 200w 12v panels to be connected in parallel with 150ah battery… I’m yet to install.

1. PL what gauge of wire did you use for your 600w solar array set up. Distance btw my panels and controller is 8 meters/27 feet and I would like to know what wire size would be appropriate and efficient.

2. Also on days that I won’t use any load in the daytime. Is there a disadvantage/danger in having such a large array because of the excess energy? I.e. will I be better off using 400w if my kids will be minimal.

3. Lastly, Will having 600w panels charge the 150ah batteries faster than 400w in good sunlight?

1. You can just use 4SQ MM DC wire from solar panels to solar inverter or solar controller. If you think length is very long, simply jump to 6SQ MM. But I think 4 SQ MM would be fine here. If you’re still confused what to use, simply use the same thickness of DC cable which is available behind the solar panel. Please only use DC cable which is durable and more heat/weather tolerant and not the regular house wiring AC cable.

2. Since your load is minimal during daytime, it will charge the battery faster. I didn’t get that kid thing.

3. Yes, it will be faster as you get more Amperes (30 max and 15~25 average) to convert and store. 200 Watts PV usually produces around 10 AMPs max current, and 3 units of it in parallel will generate around 30 AMPs max in full capacity.

But all days are not equal, so you’ll be getting around 15 to 25 AMPs and you need at least 16 AMPs to charge 150 AH battery faster.

2. Uwem

***if my loads will be minimal

1. Oh, got it now.

Yes, it will be fine.

With minimal load, the battery charges faster and reserves enough backup for night.

For better and extended backups, use only efficient lights and BLDC fans.

This will extend the backup time by twice.

1. Uwem

Thank you sir for your immediate response and clarification.

My reason for asking about the wire size is because most websites and online calculators I’ve used for that distance (8m/27ft) say I should go for a 10mm wire to keep voltage drop at or below 3% according to NEC standard and avoid energy loss/ system inefficiencies.

But like you my electrician also advised to go for a 6mm wire, saying even 4mm could still do the job.

So my question is:

1. Is this voltage drop/energy loss in my set-up not an issue. Is it negligible that I should just ignore it?

2. Will going for 10mm wire just be a waste of my precious limited money?

3. Whatever the wire, is a dual-core (two-core) wire ok to use, or is it better to use separate single core PV wires to run positive and negative terminals?

2. Welcome back. Here are the answers:

I suggest you to avoid using calculators here because they are meant for large scale setups. 2~3% loss would always be there (even when high gauge wires are used) as we are using a just 12V setup with limited Watts. Our inverter just need 12V while 12V solar panel produces more than 20V which is more than what we need. Make sure the distance between the controller/solar inverter and solar panels are always less than 10–15 meters.

1. Voltage or current drop doesn’t happen on just less than 10 or 15 meters if you use the right wires and connectors.

2. 10 SQ MM wire is overkill here and expensive too because it is meant to handle 52 AMPs and in your case maximum is 30 AMPs. So save your money here and go with 4 or 6 SQ MM.

3. Usually, solar wires come in separate cores and not in joint. Avoid using 2 cores unless your setup is too small.

I am also using around 760 Watts (Read: https://www.atulhost.com/luminous-solar-nxg-1400-inverter-ups-review), I had never faced any issue with it. If I’m counting right, it had been over 4 years and everything is working very well even today.

3. Uwem

Thanks a lot. Now I can proceed with confidence.

4. Uwem

Hello again sir, just to confirm, will the 6mm cables used to connect panels to the charge controller be sufficient for a 45a charge controller to connect to 150ah battery for 600w panel system? The charge controller manual specifies 16mm cables on its manual to connect to battery terminals.

5. Yes 6SQMM cable is enough for solar to charge controller, but from charge controller to battery connection use more thicker cable as battery operates on much higher amps current. Usually your setup is not too large or small so you can go with 10-12SQMM (as finding 16SQMM is difficult) also. But go with recommended one if you able to find that size of wire in market.

I’ve recently switched to MPPT based charge controller and that too recommends me 16SQMM, but I couldn’t find that size in my local market so I’ve combined 2 wires as 1 for both pairs (like 6SQMM*2=12SQMM). I recommend using wire lugs and battery terminals in wire if you are making one by yourself as thicker wires are not easy to fit in controllers directly.

We need little thicker cable at battery end because AMPS are higher, never use less than 10SQMM for 150AH battery. Also keep the length as short as possible between charge controller and battery, less than a meter or one and half meters would be good.

6. Uwem

Thanks very much Sir.

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

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

12. Joseph

Hello Sir, I just installed 600w panels on a 12v 150ah battery system and wanted to know if everything was working appropriately. (ie the charge controller and panels ) as I’ve already been using my inverter without them for about 3yrs

From my observations,
a. My PV’s highest amperage reading on charge controller was 18.6A. And when battery is full or load is reduced or turned off, it reduces almost immediately to about 4a or 3.7a and vice versa.

Question: I thought CC is to to give readings of what solar panels are producing regardless of whether it is being used by inverter or not. I’m I mistaken?

Also, the max current rating for my panels (3pcs 200w) is 10a each for ideal conditions offcourse and I was expecting to get at least twenty sthg amps or something close to 30amps on a very clear sunny day in West Africa but the max was 18.6 even with a lot of my loads on when battery was like half way drained. We’ve made sure all wire connections etc are correct and tight. is this normal also, as I suspect my system isn’t working in it’s full potential?

b. Also, the PV volt is usually & mostly btw 13/14V but when battery is full, the PV voltage stays at 23v. I also found out this doesn’t seem to affect the amperage reading. eg I’ve registered PV 23V, 15A (when battery was full and I decided to put a good load on it ie d amperage would go up from about 4A to 15A) and PV 14V,15A (when battery isn’t full). Pl is this normal too?

c. lastly thus far, the PV amperage and battery amp have always been reading same value on the CC. Eg even when PV got to 18.6A, battery was same. is this also normal. I though battery charging amp was to be limited to 15/16a or thereabout?

1. Hi Joseph, welcome to my blog.

Coming to your situation, you look confused about variation of charging current. If you are using decent charge controller then it will only focus on the battery bank. While some expensive charge controllers come with floating charge feature that allows you to draw as much as power from solar energy as it has a job to constantly monitor the diminishing energy from battery and charge it immediately using available solar power.

But it is okay that charge controller reduces the voltage and current to battery when it is full or not used. It still charges the battery bank in very low power to maintain the 100% charge level, because lead-acid battery tend to lose power quicker when not used.

About the voltage and current drop, it would be there as we are utilizing 12V range, while solar system would be generating 20+V. If you are using PWM controller then 25~35% drop will be there and in case of MPPT only less than 5% is lost.

Lastly, the battery voltage will always be close to 12V (+2V or 3V when it is being charged) and 15/16 AMPS no matter how many additional amps are produced by the solar panel. This is controller setting to save the battery life and you shouldn’t change it unless you know what you are doing.

1. Joseph

I’m using a 45A Epever Pwm charge controller. From what I gather from ur response, the reason behind the variations and readings on the controller is because it favours what is really going on at the battery end, Hence the fluctuations based on battery level/ load applied. I suspected so as that seems logical. Thanks

And the controller settings for the battery are auto and can’t be changed. Yes, the max is usu btw 14.4 – 14.6V while charging on the battery reading.

However where I want to be 100% clear is in the PV amperage reading on the controller (and not the battery’s reading) Am I right to infer that no matter what the panels are producing eg even if it were producing the max 30A that that’s not what the controller will reflect but what it is making use of and giving to inverter or battery? ie is this why the max I observed was 18.6A? Sorry to press the matter further

1. Right, it is the controller that only allows necessary voltage and current for the battery. I’ll suggest to use heavy load in early day time so that you have enough charging hours and energy backup for rest of the day.

13. Idim

Hi… I want to install a solar system that will not need mains supply except in rare situations. I’m in Africa where the sun is abundant. PL can u help me verify if the set up is ok. I’ve calculated my load requirements to be ok. Just lights, tv, freezer etc. I opted for 5kv over 3kv inverter for the occasional and rare use of a 1.5hp pumping machine and perhaps a 1 or 1.5hp Air Conditioner (not simultaneously). I understand to use these, one will generally need to put off all other things.

1. 5kva/24v inverter
2. 220AH battery 2units
3. 420/450w solar panels 4units
4. Charge controller 80a or 60a preferably.

Also,
a) is there need to add anything such as breakers or fuse to the set up?

b) is there any real advantage of using a hybrid inverter over the regular one?

c) And half cut solar panels over standard panels?

Thanks

1. I will recommend at least 48V system for such loads, because in 24V system you cannot run heavy loads for long time. If you can find the same load inverter with 4 battery system or 48V battery system, go with it.

a. Yes, in every heavy setup breakers and fuse is required.
b. It is just ease of using one setup, nothing much.
c. As you have more enough sunlight, there is no big benefit unless you have less space on roof. Normal ones (multicrystalline) are cheaper, but monocrystalline (half cut) saves space.