See also: What is a solar charge controller’s function?
What is the most important factor in choosing the perfect solar charge controller for your project?
When picking a controller there are a few steps that you must follow to make
sure that you get the right controller for the job. The best thing that you can do is to use
the manufacturer’s sizing tools that are offered on their web sites.
The most important job of all solar charge controllers is to properly charge the batteries and to give them as long a life as possible. There are two types of charge controllers:
Pulse width modulation (PWM)
Maximum power point tracking (MPPT)
The difference between these two types of controllers is that the PWM is not as efficient the MPPT. The MPPT is the most common these days and can gain you up to 30% more power than the PWM controllers. The MPPT controllers also allow the strings of panels to be connected in series for higher voltages, keeping the amperage lower and the wire size smaller, especially for long-wire runs to the PV array.
When picking a charge controller there are a few steps that you must follow to make sure that you get the right controller for the job. The best thing that you can do is to use the manufacturer’s sizing tools that are offered on their web sites. The other option is to give the manufacturer a call — their salespeople will usually be happy to help you to pick the best controller.
If you need to make some quick calculations, the following information will be needed to manually figure out the amperage of the controller needed:
The wattage of the solar array
The battery-bank voltage (12, 24, or 48). Typical bank voltage because inverters are offered in these voltages.
Now Ohm’s Law comes into play: Amps x Volts = Watts
Example: 3,000watt array/48volt battery bank = 62.5 amps, so you would need a controller capable of 62.5 amps. Most controllers out there are either 60, 80 or 96 amps so you would pick the controller with the next higher rating. In this case, it would be the 80 amp controller.
Now if you know the amperage of the controller, and you would like to figure out how the maximum solar array wattage that can go into the controller, you would also use Ohm’s law:
Example: 80 amp controller x 48 volt battery bank = 3,840 watts of solar panels. Note that most of the controllers will allow a bit more wattage to go into the controllers. This is where the sizing tools or a call to the manufacture can help out.
The next thing that you must ensure is that we do not exceed the input voltage the controller can take. Again the manufacturer will dictate what the input voltage should be included in the design. Temperature and open-circuit voltages have to be considered. Since PV open-circuit voltage (Voc) goes higher as temperature drops, you will need to make sure the controller’s input voltage ratings can handle this in the cold of winter. Manufacturer’s sizing tools will give you the best design for the controllers.
There are many makes and models of charge controllers available, but it’s best to get the most options for the best price. The following is a list of features available on charge controllers — but not all controllers. The best will offer every option.
- 150,200,250,600 V
- Manual and auto EQ
- Built in GFP and arc fault
- Online status monitoring
- Hyper VOC extend VOC limits
- 12-72 volt battery charging
- Solar, wind and hydro MPPT modes
By boB Gudgel & Kim Silva, MidNite Solar
I have a single, 100 watt panel and I want to get a good charge controller. Can you recommend a charge controller for my sityation.
Hie guys. I’m having a 255watt solar panel and 2× 12volt batteries. how many Amps of a controller can I use please. Thanks for your help
I am new in this solar charge business. I have 2 X 60 watt solar panels, a 10 amp controller and a 120aH deep cycle battery. Will this be sufficient to run my 5 amp 12 volt freezer?
Your 120ah / 12v battery has 1440w when fullly charged
Your 12v / 5amp freezer will use 60w When running
It Can run 16hrs On a Full battery continously
With 2x 60w panels you are safe…
Alright. I have tried to figure out the math calculations and I am getting NOWHERE. My question is: I am using 3 305 watt residential panels on my RV and mating them to 1K ah Lithium bank (Battleborns !) Can someone PLEASE tell me which MPPT charger/controller/inverter (?) I need to focus on. PLEASE. Thank you.
Mike- Did you have your batteries connected to the charge controller as well? Some controllers will not display voltage unless there is a load on the system…IE The batteries would be the load as they are the ones being charged.
Hi, I have a question regarding Charge Controllers, I have a simple solar set used to power a small tool shed on my property. I have (2) 12V / 100W Solar Panels and 8 marine type deep cycle 12V battery’s. When I use a multi meter and check voltage coming out of the panels I’m getting 19.30 volts but when I connect to a charge controller it shows 0 voltage coming in ?..I had 20amp charge controller that worked for a long time then got hot and stopped showing input voltage, I just purchased a cheap 100Amp controller on ebay and it does same thing, no input voltage from panels. Ive checked the out put of the panels together and individually, both show them putting out 19V, Any suggestions, anything I am missing or could it all be the fault of cheap charge controllers …thanks for any input.
Is your charge controller connected to the batteries as well? Some charge controllers are looking for a load so the batteries would be the load.
I have a 240 volt freezer with a power of 115 watt. What size panel, battery & charge controller will I need if I were to use a solar system of 12 volts?
It seems the administrator is gone to sleep. Nobody received any answer to their inquiries.
I’m afraid I’m not the best at math! I would suggest anyone with questions about charge controllers reach out to charge controller manufacturers like MidNite Solar (featured in this story).
Example: 80 amp controller x 48 volt battery bank = 3,840 watts of solar panels. Note that most of the controllers will allow a bit more wattage to go into the controllers but you must ensure that you do not exceed the input voltage the controller can take.
93Amps exceed the 80A limitation that thr charge controller can handle.
I have an 80 Watts solar panel made by Sharp
to use for two lights at the beginning of my long driveway.
1-What kind of controller do I need?
2- Do I need more a 12 Volt battery?
how much is the wattage of the two lights that you will use. is it 5 watts or 20 watts? A PWM 12 V Charge Controller is enough with one battery 12 volts 35 A-H is enough.
Hello, I’m new to solar panel installations. I have 4 solar panels of 245W each. A power bank of 102 AH on 12V and a PWM regulator with 40A. On the regulator it says Max PV Input power 480 W for 12V but I connected all 4 solar panels and now the regulator won’t charge the batteries any more (most likely I burned it). Should I just leave 2 solar panels connected? Thank you
I have 24 volts batteries bank in series of 200 Ah and have two solars of 24 volts which are giving out volts of 36 max so which charge controller is best to charge my batteries to get best result and also simultaneously get load for appliances
50A is too small for your system. Get around 70-80 Amps.
p.s. the controller i have burned out details can be find here https://www.ebay.co.uk/itm/Hybrid-Wind-solar-charge-controller-wind-regulator-12V-24V-charge-controller/122019286305?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
how or why did it burn out?
Hello,
I have 2x12v 240a batterys, i have connected them 12v 480a (paralel connection). I need information what charger controler i need for it, as i got 160w solar panel and 400w wind turibine. I have just burned my Hybrid Wind solar charge controller, wind regulator 12V 24V charge controller, everything inside melted – couple lines burned out and one of the brains completely burned out. Is it because of the powerfull batteries i have or its just kind of faulty charger? Any help will be nice. Dont want to buy another one just to burn it again.
Many Thanks
Ged
Is it okay to have big amperage of charge controller than its normal ratings let say double its nominal amps.
Commenters, the author makes an effort to supply the formula (and if you don’t believe him, look up ohm’s law, watts law). Learn to fish, and eat forever.
What charge controller do I need for an 12 volt 9 – 100 watt solar panel array? 900 watts and 12 volts. I want to wire panels in series.
hey there .. fishing here .. i am in the philippines. i have an off grid system … 14panels @ 100 w each. MPPT CONTROLLER 50A .. 24V SYSTEM BATTERY BANK .. 10 100 AMP BATTERIES.
IS MY CONTROLLER TOO small in amps? will it hurt my batteries .. i suspect not .. but am i wasting charging current?
I have a 60amp solar regulator, so how many solar panels and batteries I need to cater for 60amp regulator
Thanks for sharing. I want a you to take a cross check my calculation. I have a 3600Wp array with 48V battery bank. Am doing 3600/48 = 75A X 1.25 = 93A. Is it ideal to use an 80A CC.
Hi,the formular you used at arriving at your answer is very correct
Go for the 100A controller
Dear sir ,
I have installed 600watt solar panel and I want to increase the back up time of the system kindly suggest me what is the best way to improve it. the present solar system description as follows
Pwm 12V/24v 30A charge controller
1400VA inverter 24v
24V 150AH*2=300Ah battery
Kindly, what are the problems and the difficults in designing the MPPT charger controller?