How many watts can a 100 amp charge controller handle?

The watt limit of any charge controller will give you an idea of how many watts of solar panels it can handle or what size solar panels you can connect with it

So in this blog, we’ll see how many watts a 100A charge controller can handle and what size battery will be suitable with a 100A charge controller

100 amp charge controller can handle 1200 watts in 12v system, 2400 watts in 24v system and 4800 watts in 48v solar array By multiplying the amps of a charge controller with voltage nominal of battery

100 Amp charge controllers are mostly designed to use for 24v or 48v solar arrays not for 12v solar systems or batteries.

Now let’s see how you can calculate the watt limit of the charge controller

How charge controller work

First of let’s discuss what is the job of the charge controller and how they work and why are they important.

a regulator or charge controller regulates the DC current produced by the solar panels to charge the batteries

if you have 12v batteries and your solar panels are producing 18 volts so a charge controller will decrease the volts to match the input voltage of the battery (12V)

here’s a PWM and MPPT charge controller that makes the difference. A PWM charge controller will only decrease the volts and the amps will stay the same which will cause a loss of power. Power formula amps x Volts = Watts

An MPPT charge controller decreases the volts to match the battery and will also increase the amps to get the maximum watts from the solar panels to charge the battery

If you’re using a large-sized charge controller like 100A then it is always recommended to use an MPPT charge controller

How to calculate regulator watt limit?

The calculation of watt limit of a charge controller will be determined by the nominal voltage of the battery

use this formula to calculate the regulator watt limit

amps (Charge controller) x Volts (Battery) = Charge controller watt limit

let’s suppose if you’re using a 24-volt battery and 24v array solar panels then multiply those volts with the amps of the charge controller

  • 24 volts x 100 amps = 2400 watts
  • 48 volts x 100 amps = 4800 watts
  • 12 volts x 100 amps = 1200 watts

This is how you can calculate the watt limit of any charge controller. And keep in mind some charge MPPT charge controllers would be able to handle a little bit more watts but most of the experts recommend using a charge controller at it only 80% of capacity for safety factors

in winter at low temperature, the volts coming from solar panels can increase which will cause a fluctuation in the voltage so if your charge controller is already using its 100% capacity so a little spark of a high volt can damage the controller or batteries or even solar panels

With MPPT charge controller keep in mind about the battery or power bank voltage if the battery is 12v then the watt limit of the controller will be according to 12v even if the solar panels are producing 24 or 48 volts

Using a 100A PWM charge controller will cause a huge loss in power due to their only 70%. because it will only reduce the high voltages coming from the solar panels to match the input voltage of the battery or power bank but amps will stay the same

to calculate the power we use this formula amps x volts = total power

eg if you have a 48v 1000w solar panel under ideal sunlight conditions it will produce about 55-60 volts and amps will be 16.6 amps so and PWM charge controller will reduce the volts to 48 volts to charge the battery with 16.6 amps

16.6 x 48 = 796 watts which will cause 200 watts of power.

On the other hand, an MPPT charge controller will reduce the volts but will increase the amps which result make them 95-99% efficient which is 30% more than the PWM charge controller

How many solar panels can a 100A charge controller handle?

To calculate the size of solar panels for a 100A charge controller, the rule of thumb is that the total amps of solar panels should not increase by 100 amps and the volts should match the battery volts

so if you’re connecting 200w 12v solar panels how many of them you can connect in parallel or series?

as we know that a 100a solar charge controller can handle 1200 watts maximum on a 12v array and 2400 watts on a 24v array

Let’s assume that your 200w solar panels are producing 200w of power under ideal sunlight conditions but the voltage will be high so if you’re charging a 12v battery and using an MPPT charge controller it will automatically decrease the voltage to match the ax input volt of the battery which a 12v battery can handle 14 volts

1200/200 = 6

you can connect 6 12 volts 200w solar panels in parallel to charge a 12v battery with the help of a 100a MPPT regulator but you can not excide beyond 6 200 solar panels because it will increase the total amps of solar panels than what a charge controller can handle (100 amps)

to calculate the amps (amps = watts/volts) 200/12= 16.6 amps / per solar panel

16.6 x 6 (no fo solar panels) = 100 amps

so you’ll be using your controller’s 100% capacity with 6 200w solar panels connected in a 12v array

But make sure that you’re using a high-quality wiring size that can handle that much of amp load I recommend using a 6 AWG wire size

2400/200 = 12

you can connect 12 24v 200w solar panels with a 100 amp charge controller to charge the 24v battery

I’ve discussed in detail about connecting solar panels in parallel or series Read More…

just to be quickly connecting your solar panels in parallel will add the amps but the voltage will stay the same in series the voltage will add up and the amps will stay the stay

What battery size for 100A charge controller?

as we know that a 100a controller can handle 100 amps per hour so if your solar panels are producing 100 amps per hour in total they will produce about 500 amps of power in total in a day

so you can charge a 500Ah battery in a day with a 100a charge controller and right size solar panels

you can connect 5 200Ah deep cycle batteries in series with a 50% limit of discharge

you’ll need a double-sized battery that a 100a charge controller will pass because most deep cycle batteries are only allowed to be discharged by only 50%.


a 100a charge controller can handle a huge load of power so it’s very important to keep in mind the few points so you should know how much exactly it can handle and what size of solar panels you can attach with it.

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Chris Tsitouris is a renewable energy professional with 10+ years of experience as Director of Engineering at Solar Spectrum, previously working as Project Manager at SunPower and Energy Analyst at the National Renewable Energy Laboratory. As a thought leader, Chris has authored numerous articles and research papers.

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