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
Junaidu says
May 18, 2019 at 8:44 amI have installed 150*3 = 450 solar panels, which controller is the best for my installation. my inverter is 12v. 20A or 30A
Palacious says
May 14, 2019 at 12:27 pmHello, i have 48v battery and 4 numbers of 300watts solar panels, i grouped the 4 solar panels 2 by 2 and connected them serially, then connected the output of the pairs parallel to the outgoing cable, reading the output i am getting 100v, what charging controller should i use?
Billy Ryan says
April 6, 2019 at 8:12 amI could see some answers to most of the questions about selecting the right solar charge controller can be found here: https://alternativeenergysourcesv.com/best-solar-charge-controller/
Joy Xiang or 向凤乔 says
April 24, 2019 at 6:12 amStep 1- Voltage selection. Select a charge controller that is compatible with the overall solar panel output voltage. The standard configurations are 12, 24, 36 and 48 V
Step 2 – Current capacity. Select a charge controller that can handle the maximum output current of the solar panel (or solar array).
Below you will find a quick guide to choosing the proper charge controller for several popular solar panel sizes.
Our controller contains 2 types regarding voltage: 12/24V and 12/24/36/48V, Meaning for Type 1 12V and 24V are compatible in one system.
And for Type 2 12V, 24V 36V and 48V are compatible in one system.
12V PV system within 160W: 10A 12/24V, 24V will work
20A 12/24V 24V will work
24V PV system within 200W: 20A 12/24V
24V PV system within 240W: 20A 12/24V or 20A 12/24/36/48V
24V PV system within 360W: 20A 12/24/36/48V
24V PV system within 480W: 20A 12/24/36/48V or 30A 12/24/36/48V
24V PV system within 600W: 30A 12/24/36/48V
36V PV system within 600W: 20A 12/24/36/48V or 30A 12/24/36/48V
36V PV system within 800W: 30A 12/24/36/48V
36V PV system within 1000W: 50A 12/24/36/48V
36V PV system within 1500W: 50A 12/24/36/48V
36V PV system within and above 2000W: 80A 12/24/36/48V
48V PV system within 800W: 30A 12/24/36/48V
48V PV system within 1000W: 30A 12/24/36/48V or 50A 12/24/36/48V
48V PV system within 1500W: 50A 12/24/36/48V
48V PV system within 2000W: 50A 12/24/36/48V or 80A 12/24/36/48V
48V PV system above and within 2500W: 80A 12/24/36/48V
that girl nahavi says
March 2, 2019 at 8:15 amI am to build an Arduino based PWM solar charge controller with a rated charging current of 20A and am new to this and stuck on what calculations should guide me in achieving the charge controller. any guidance will be appreciated
Joy Xiang or 向凤乔 says
April 24, 2019 at 6:18 amIf your rate charging current is 20A, then you need to choose a controller with current 30A or above, namely 40A 50A or 80A. Then regarding the voltage, you can calculate in this way: V=P(SOLAR PANEL OVERALL OUTPUT WATT)/current.
For any more inquiry, please feel free to contact me.
bisaso daniel says
February 22, 2019 at 5:58 amI have a UPS inverter of 180v and mttp charge controller of 180v battery input, 420v maximum panel
40pcs of solar panel 48vlts 250 watts and 26 PCs of batteries of 12vlts 250imphrs how can I connect them b’se they have failed to charge
Dave says
January 22, 2019 at 5:22 amI have a 500 W solar and a 500 W wind. I want to get an MPPT charge controller. any tips
?
Joy Xiang or 向凤乔 says
April 24, 2019 at 8:42 pmHello, Dave, since i only deal with solar charger controller, i can only tell you for the 500W solar panel, you should know its output voltage, which is equal to the controller voltage. And then 500W/V=Current of the solar panel, the controller current must be bigger than it.
e.g. if the voltage is 36V, the current is 13.89A, then a 36V20A controller is OK.
For more details, you can contact me by whats app, my phone no. is 17612164059
Jack Zahrly says
January 10, 2019 at 10:37 amI have a single, 100 watt panel and I want to get a good charge controller. Can you recommend a charge controller for my sityation.
Joy Xiang or 向凤乔 says
April 24, 2019 at 8:46 pmHello, Mr. Zahrly. For your panel, a 10A12V PWM controller is OK. Our controller provides 4-stage charging for maximum extension of battery life and 4 load working modes. For further enquiry, please contact me by what’s app 17612164059.
Samuel says
December 5, 2018 at 4:38 pmHie 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
Joy Xiang or 向凤乔 says
April 24, 2019 at 8:49 pmHello, Samuel. In your case, a 20A24V controlLer is OK for you, because the controller must be able to handle the maximum current of the system.
For more details, you can contact me by whats app, my phone no. is 17612164059
Manie du Plessis says
October 30, 2018 at 7:22 amI 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?
Berend says
December 23, 2018 at 7:10 amYour 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…
JOHN D BIRMINGHAM says
October 21, 2018 at 1:29 amAlright. 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.
tarn says
March 29, 2019 at 7:12 pmNot all charge controllers can run on lithium batteries some are made for lead only your solar panels set up at parallel rate 300watt house panels are usually 36v so parallel you need a controller that rates 50v pv input if you are series the controller needs to be 3x the panels 36v im a novice just learning but i do know alot of people forget to check the volts input and burn out controllers
Donald Dubuque says
October 16, 2018 at 11:41 pmMike- 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.
Mike says
September 28, 2018 at 10:21 amHi, 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.
Donald Dubuque says
October 16, 2018 at 11:43 pmIs your charge controller connected to the batteries as well? Some charge controllers are looking for a load so the batteries would be the load.
Dobson says
August 21, 2018 at 9:16 pmI 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?
Ziyad A Zaitoun says
July 26, 2018 at 4:02 pmIt seems the administrator is gone to sleep. Nobody received any answer to their inquiries.
Kelly Pickerel says
July 26, 2018 at 4:31 pmI’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).
Wayne says
July 17, 2018 at 1:48 amExample: 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.
Ziyad A Zaitoun says
July 13, 2018 at 1:52 amI 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?
Joey says
August 20, 2018 at 9:14 amhow 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.
Andrei says
July 10, 2018 at 12:58 pmHello, 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
tarn says
March 29, 2019 at 7:19 pmAre your solar panels set up parallel or series because the pv input volts need to match the the charge controller or you will cook it
M Shoaib Ghouri says
July 9, 2018 at 11:11 pmI 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
dennis says
June 30, 2018 at 5:35 pm50A is too small for your system. Get around 70-80 Amps.
Ged says
March 11, 2018 at 12:35 amp.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
Tina says
April 13, 2018 at 6:31 pmhow or why did it burn out?
Ged says
March 11, 2018 at 12:34 amHello,
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
Ed says
January 30, 2018 at 7:42 amIs it okay to have big amperage of charge controller than its normal ratings let say double its nominal amps.
Marlon says
December 27, 2017 at 9:57 amCommenters, 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.
NICK MCMILLEN says
December 20, 2017 at 5:26 pmWhat 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.
carl says
December 8, 2017 at 1:39 pmhey 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?
Jerome says
October 31, 2017 at 1:40 amI have a 60amp solar regulator, so how many solar panels and batteries I need to cater for 60amp regulator
Chi says
September 20, 2017 at 2:56 amThanks 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.
Egure sunday says
July 24, 2018 at 2:45 amHi,the formular you used at arriving at your answer is very correct
Donald Dubuque says
October 16, 2018 at 11:44 pmGo for the 100A controller
Mahantesh says
July 18, 2017 at 10:22 amDear 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
doaa says
July 10, 2017 at 6:19 amKindly, what are the problems and the difficults in designing the MPPT charger controller?