Solar Charge Controller Types, Functionality and Applications
A solar charge controller is fundamentally a voltage or current controller to charge the battery and keep electric cells from overcharging. It directs the voltage and current hailing from the solar panels setting off to the electric cell. Generally, 12V boards/panels put out in the ballpark of 16 to 20V, so if there is no regulation the electric cells will damage from overcharging. Generally, electric storage devices require around 14 to 14.5V to get completely charged. The solar charge controllers are available in all features, costs, and sizes. The range of charge controllers is from 4.5A and up to 60 to 80A.
Types of Solar Charger Controller:
- Simple 1 or 2 stage controls
- PWM (pulse width modulated)
- Maximum power point tracking (MPPT)
Simple 1 or 2 Controls: It has shunt transistors to control the voltage in one or two steps. This controller basically just shorts the solar panel when a certain voltage is arrived at. Their main genuine fuel for keeping such a notorious reputation is their unwavering quality – they have so not many segments, there is very little to break.
PWM (Pulse Width Modulated): This is the traditional type charge controller, for instance, anthrax, Blue Sky, and so on. These are essentially the industry standard now.
Maximum power point tracking (MPPT): The MPPT solar charge controller is the sparkling star of today’s solar systems. These controllers truly identify the best working voltage and amperage of the solar panel exhibit and match that with the electric cell bank. The outcome is extra 10-30% more power out of your sun oriented cluster versus a PWM controller. It is usually worth the speculation for any solar electric systems over 200 watts.
Features of Solar Charge Controller:
- Protects the battery (12V) from overcharging
- Reduces system maintenance and increases battery lifetime
- Auto charged indication
- Reliability is high
- 10amp to 40amp of charging current
- Monitors the reverse current flow
The function of the Solar Charge Controller:
The most essential charge controller basically controls the device voltage and opens the circuit, halting the charging, when the battery voltage ascents to a certain level. charge controllers utilized a mechanical relay to open or shut the circuit, halting or beginning power heading off to the electric storage devices.
Generally, solar power systems utilize 12V of batteries. Solar panels can convey much more voltage than is obliged to charge the battery. The charge voltage could be kept at the best level while the time needed to completely charge the electric storage devices is lessened. This permits the solar systems to work optimally constantly. By running higher voltage in the wires from the solar panels to the charge controller, power dissipation in the wires is diminished fundamentally.
The solar charge controllers can also control the reverse power flow. The charge controllers can distinguish when no power is originating from the solar panels and open the circuit separating the solar panels from the battery devices and halting the reverse current flow.
Applications:
In recent days, the process of generating electricity from sunlight is having more popularity than other alternative sources and the photovoltaic panels are absolutely pollution free and they don’t require high maintenance. The following are some examples of where solar energy is utilizing.
- Street lights use photovoltaic cells to convert sunlight into DC electric charge. This system uses a solar charge controller to store DC in the batteries and uses it in many areas.
- Home systems use a PV module for house-hold applications.
- A hybrid solar system uses for multiple energy sources for providing full-time backup supply to other sources.
Example of Solar Charge Controller:
From the below example, in this, a solar panel is used to charge a battery. A set of operational amplifiers are used to monitor panel voltage and load current continuously. If the battery is fully charged, an indication will be provided by a green LED. To indicate undercharging, overloading, and deep discharge condition a set of LEDs are used. A MOSFET is used as a power semiconductor switch by the solar charge controller to ensure the cut offload in low condition or overloading condition. The solar energy is bypassed using a transistor to a dummy load when the battery gets full charging. This will protect the battery from overcharging.
This unit performs 4 major functions:
- Charges the battery.
- It gives an indication when the battery is fully charged.
- Monitors the battery voltage and when it is minimum, cuts off the supply to the load switch to remove the load connection.
- In case of overload, the load switch is in off condition ensuring the load is cut off from the battery supply.
A solar panel is a collection of solar cells. The solar panel converts solar energy into electrical energy. The solar panel uses Ohmic material for interconnections as well as the external terminals. So the electrons created in the n-type material passes through the electrode to the wire connected to the battery. Through the battery, the electrons reach the p-type material. Here the electrons combine with the holes. When the solar panel is connected to the battery, it behaves like other battery, and both the systems are in series just like two batteries connected serially. The solar panel has totally consisted of four process steps overload, under charge, low battery, and deep discharge condition. The out from the solar panel is connected to the switch and from there the output is fed to the battery. And setting from there it goes to the load switch and finally at the output load. This system consists of 4 different parts-over voltage indication and detection, overcharge detection, overcharge indication, low battery indication, and detection. In the case of the overcharge, the power from the solar panel is bypassed through a diode to the MOSFET switch. In case of low charge, the supply to MOSFET switch is cut off to make it in off condition and thus switch off the power supply to the load.
Solar energy is the cleanest and most available renewable energy source. Modern technology can harness this energy for a variety of uses, including producing electricity, providing light and heating water for domestic, commercial or industrial applications.
What is a solar charge controller and why are they important?
As the name suggests, a solar charge controller is a component of a solar panel system that controls the charging of a battery bank. Solar charge controllers ensure the batteries are charged at the proper rate and to the proper level. Without a charge controller, batteries can be damaged by incoming power, and could also leak power back to the solar panels when the sun isn’t shining.
Solar charge controllers have a simple job, but it’s important to learn about the two main types, how they work, and how to pair them with solar panels and batteries. Armed with that knowledge, you’ll be one step closer to building an off-grid solar system!
Find out how much you can save by installing solar
Key takeaways
- Solar charge controllers allow batteries to safely charge and discharge using the output of solar panels.
- A charge controller is needed any time a battery will be connected to the direct current (DC) output of solar panels; most often in small off-grid systems.
- The two kinds of charge controllers are pulse-width modulation (PWM) and maximum power point tracking (MPPT).
- PWM charge controllers are less expensive, but less efficient, and are best suited for small off-grid systems with a few solar panels and batteries.
- MPPT charge controllers are more expensive and more efficient, and are good for larger off-grid systems that can power a small home or cabin.
- The top off-grid charge controllers are made by brands like Victron, EPEVER, and Renogy, but non-brand-name charge controllers can be just fine if you know what to look for.
Who needs a solar charge controller?
A charge controller is necessary any time a battery bank will be connected to the direct current (DC) output of solar panels. In most cases, this means a small off-grid setup like solar panels on an RV or cabin. If you’re looking for information on how to use solar and batteries off the grid, you’re in the right place!
There are also charge controllers aimed at providing battery backup for an existing grid-tied solar system that is on the roof of a home or business. This application requires a high-voltage charge controller and usually involves rewiring the system to direct a portion of the solar output through the charge controller.
How does a solar charge controller work?
Fair warning before we get started: we’re about to discuss voltage, amperage, and wattage. If you need a refresher on how these things work together, check out our article on watts, kilowatts, and kilowatt-hours.
A solar charge controller is connected between solar panels and batteries to ensure power from the panels reaches the battery safely and effectively. The battery feeds into an inverter that changes the DC power into AC to run appliances (aka loads).
How a charge controller works within an off-grid solar system.
The four main functions of a solar charge controller are:
- Accept incoming power from solar panels
- Control the amount of power sent to the battery
- Monitor the voltage of the battery to prevent overcharging
- Allow power to flow only from the solar panels to the batteries
As a battery charges, its voltage increases, up to a limit. The battery can be damaged if an additional charge is applied past this limit. Therefore, the ability of a battery to provide or accept power can be measured by its voltage. For example, a typical 12-volt AGM lead-acid battery will show a voltage of 11.8 volts at 10% charged to 12.9 volts at 100% charge.
The main function of a solar charge controller is to ensure the amount of power that is sent to the battery is enough to charge it, but not so much that it increases the battery voltage above a safe level. It does this by reading the voltage of the battery and calculating how much additional energy is required to fully charge the battery.
Another important function of the charge controller is to prevent current from traveling back into the solar panels. When the sun isn’t shining, the solar panels aren’t producing any voltage. Because electricity flows from high voltage to low voltage, the power in the battery would flow into the solar panels if there was nothing in place to stop it. This could potentially cause damage. The charge controller has a diode that allows power to flow in one direction, preventing electricity from feeding back into the panels.
How solar power gets from panels to batteries
As we mentioned above, power flows from high voltage to low. So, to add energy to the battery, the output voltage of a solar panel must always be a little higher than the voltage of the battery it’s charging. Thankfully, solar panels are designed to put out more voltage than a battery needs at any given time.
Here’s an example: Say you have a single 100-watt solar panel and a 12-volt battery. Remember from above that a 12-volt battery is actually able to charge up to about 12.9 volts. 12 volts is what is called its “nominal voltage,” while the actual voltage of the battery depends on how charged it is. It might sink to 11.8 volts at low charge, and 12.9 volts when full.
The 100-watt solar panel can put out a maximum of 18 volts, which is a little too high for the battery to accept safely. Leaving it connected to the battery too long could result in a dangerous situation, eventually causing pressure to build up inside the battery and vent out the side as chemical steam.
You need a charge controller in between the solar panel and the battery to limit the voltage available to the battery. But it’s not just about the voltage. it also has to withstand a certain amount of current (amperage) flowing through it. That’s where the amperage rating of the charge controller comes in.
Charge controller amperage rating
The number of amps of current a charge controller can handle is called its “rating.” Exceeding the amperage rating can cause damage to the wiring within the charge controller. Let’s consider a charge controller rated to handle 30 amps of current. The single 100- watt solar panel described above puts out 5.5 amps of current at 18 volts. That amperage is much lower than the charge controller’s maximum of 30 amps, so the charge controller can easily handle the output of the singular solar panel.
In fact, it could handle the output of multiple solar panels wired in parallel (which increases current output). But there’s an important rule about charge controller ratings to consider: always make sure your charge controller is rated to handle 25% more amps than your solar panels are supposed to put out. That’s because solar panels can exceed their rated current output under especially bright sun, and you don’t want to fry your charge controller on the rare occasion when that happens.
Keeping that rule in mind, the 30-amp charge controller in our example could accept a nominal output of up to 24 amps. You could wire as many as four of those 5.5-amp solar panels in parallel to create a solar array capable of putting out 22 amps, staying under the charge controller’s rating plus the 25% cushion. If you think you might expand the size of your solar array in the future, get a charge controller rated for 50% more amps than your immediate needs.
Matching voltages
Another consideration when choosing a charge controller is the voltage of the battery bank you want to charge. Wiring batteries in series increases the voltage they can deliver and accept. For example, two 12-volt batteries wired in series will operate at 24 nominal volts. There are charge controllers on the market that can pair with battery banks of 12, 24, 36, and 48 volts. You need to make sure the charge controller you purchase can pair with the voltage of the battery bank.
Battery charging stages
There are three stages of charging a battery: bulk, absorption, and float. They correspond to how full the battery is.
- Bulk: When a battery charge is low, the charge controller can safely push a lot of energy to it, and the battery fills up with charge very quickly.
- Absorption: as the battery nears its full charge (around 90%), the charge controller reduces its current output, and the battery charges more slowly until it’s full.
- Float: when the battery is full, the charge controller lowers its output voltage just a bit to maintain the full charge.
Think of it like pouring water from a pitcher into a cup with a very slow leak: when the cup is empty, you start pouring and quickly increase the amount of water being poured until the cup is nearly full. Then you reduce the flow until the cup is full. In order to keep the cup full despite the leak, you pour just a trickle to keep it topped off.
The bulk/absorption/float process was developed for lead-acid deep cycle batteries. Some newer lithium batteries allow for higher current up until they’re quite full, meaning a charge controller paired with a lithium battery can be set to shorten or eliminate the absorption stage.
Types of charge controller
There are two main ways to control the flow of power to a battery, and they correspond to the two types of charge controller: pulse-width modulation (PWM) and maximum power point tracking (MPPT).
Pulse-width modulation (PWM)
Pulse-width modulation is the simplest and cheapest automatic way to control the flow of power between solar panels and a battery. There are PWM charge controllers on the market for between about 15 to 40.
A PWM charge controller ensures the battery never charges to more than its maximum voltage by switching the power flow on and off hundreds of times per second (i.e. sending “pulses” of power) to reduce the average voltage coming from the solar panels. The width of the pulses reduces the average output voltage.
Here’s an image to illustrate how the pulses work:
For example, if the charge controller accepts 18 volts from the solar panel, it might adjust the pulses so they’re on 82% of the time, and off 18% of the time. This would reduce the average voltage by 18%, down to about 14.8 volts, which can be used to charge a half-full AGM battery. As the battery gets close to a full charge, a PWM charge controller shortens the pulses even further, down to around 77% of the time, or 13.8 volts, to prevent the battery from overcharging.
Unfortunately, the excess energy produced by solar panels is wasted to reduce the output voltage. In our example, the charge controller would average around 80% efficiency. This means it’s very important to make sure the output voltage of the solar panels is not too much higher than the voltage of your battery bank with a PWM charge controller to minimize wasted energy. If your solar array outputs a much higher voltage, the PWM charge controller will cut that voltage down to what the battery can accept, and waste the rest.
Something like 80% efficiency is fine for small off-grid applications like a few solar panels hooked up to a couple of batteries, especially at the low cost of a PWM charge controller. For larger systems with much higher output, it is generally preferable to use the other kind of charge controller technology known as maximum power point tracking, or MPPT.
Maximum power point tracking (MPPT)
An MPPT solar charge controller operates by converting the incoming power from solar panels to match the theoretical highest-efficiency output at the right input voltage for the battery. The charge controller does this by calculating the point at which the maximum current can flow at a voltage the battery can accept, then converting the solar panel output to that mixture of voltage and current.
The major advantages of MPPT charge controllers are greater efficiency and compatibility with higher voltage solar arrays. This means that you can charge a 12V battery bank with a larger solar array wired in series, as long as you stay within the limits of the controller’s amperage rating. You can calculate this limit by taking the total wattage of the solar array and dividing it by the voltage of the battery bank to get the maximum possible output in amps.
Let’s use the same example numbers as before. The solar panel is putting out 100 watts, or about 5.5 amps into 18 volts. The MPPT charge controller converts the output to 14.8 volts but loses about 5% of the power in the conversion process. So the MPPT controller’s output current is about 6.4 amps, times the 14.8 volts, or 95 watts.
Theoretically, in an hour of full sun, the MPPT charge controller will have delivered 95 amp-hours of energy to the batteries, compared to the PWM charge controller’s energy output of about 80 amp-hours. In practice, it isn’t quite that simple, as solar pro Will Prowse discovered in this video:
Common features and settings on a charge controller
The basic features of the simplest PWM charge controller include the ability to set the type of battery and battery bank voltage, and lights indicating the phase of charging (bulk, absorption, and float). advanced PWM and MPPT models come with a small LCD display for programming and data display, a heat sensor port to monitor battery temperature, and a communications port to connect the charge controller to an external display or computer. The most advanced charge controllers offer Bluetooth connectivity and an app for customizing settings.
Recommended prodcuts
There are tons of fine charge controllers available on the market. Search any solar supply or online marketplace like Amazon and you’re bound to turn up dozens of results.
The cheapest PWM charge controllers can be had for around 15, and are often rebranded versions of the same design. These lack many features but are relatively reliable for how inexpensive they are. expensive PWM charge controllers built with better quality materials can be had for under 50, while full-featured MPPT charge controllers are priced anywhere from 100 to 200.
Below are a few of our recommended charge controllers at different price points for a medium-sized off-grid setup.
Renogy Wanderer 30A 12V PWM
The Renogy Wanderer 30A PWM charge controller is a solid choice for a smaller off-grid setup. It can handle up to 30A of current at 12V, so it’s not meant for a large system.
It doesn’t have a screen, but it does pair with the three main kinds of lead-acid batteries as well as lithium ones. It has a connector port for an optional temperature sensor and includes an RS232 port that can be used to program the charge controller or even to add Renogy’s BT-1 Bluetooth module for connecting to the Renogy app on your smartphone.
The Wanderer can be had for about 40 from Amazon or Renogy direct.
EPEVER Tracer BN 30A 12V/24V MPPT
The EPEVER Tracer BN MPPT 30A charge controller is not the cheapest MPPT charge controller on the market, but it’s a very good one. With a die-cast aluminum body, sturdy connectors, and a DC output to power loads like DC appliances or LED lights, the Tracer BN is a robust piece of equipment perfect for handling solar charging of lead-acid batteries in 12- and 24-volt banks. It can accept an incoming power output of up to 2,340 watts of solar panels (that’s equal to three parallel strings of four 60-cell solar panels wired in series). The Tracer can be programmed to charge lithium batteries, but it doesn’t come with a preset charging profile for them.
This EPEVER Tracer BN kit at Amazon includes a temperature sensor, mounting hardware, and a separate screen for programming and monitoring the health and state of charge of your battery system. Price at the time of publishing was 179.99.
Victron Energy SmartSolar 30A 100V MPPT
Victron is one of the most trusted solar brands in the world, and its technology is now becoming more widely available in the United States. This 30A, 100V charge controller is known as one of the best on market. Just like the EPEVER controller, it works with 12- or 24-volt battery banks but allows for slightly lower voltage solar input. To stay under this charger’s rating, you could run as many as three parallel strings of three 60-cell solar panels in series to achieve an output of 90 volts at around 20 amps (1,800 watts of solar output).
It’s made with quality components, calculates maximum power point quickly and with high efficiency, and is very easy to use. The SmartSolar line of charge controllers all come with Bluetooth connectivity on board and can connect to the VictronConnect app on Android, iOS, macOS, and Windows for easy programming. Perhaps most importantly, you get a 5-year limited warranty that protects you against defects in materials and workmanship.
The SmartSolar 30A is the most expensive product on our list at around 225 on Amazon, but reading the reviews from its users, you can see why the expense might be worth it.
Solar charge controllers: are they right for you?
All the information above should give you a good basis of knowledge about how solar charge controllers work and how to pair them with solar panels and batteries, but there’s no substitute for practical, hands-on experience! If you have a few bucks to spend, you can set up a pretty simple off-grid solar “generator” using a single solar panel, a charge controller, a battery, and a cheap inverter. Choosing a charge controller that’s oversized for a small application gives you a chance to increase the size of the solar array and battery bank as you gain experience or find new ways to use the stored solar energy.
Now go out there and start making solar and batteries work for you!
Connect Solar Panels To Charge Controller (Calculated)
The function of a charge controller is to protect the battery bank from damage due to overloading and overcharging. Two solar panels are connected in series or parallel to a charge controller linking it to the battery bank. Assuming we have two standard-100 W (Watt) solar panels, each generating 20 V (volts) at 5 A (amps) charging a 12 V battery.
In series, the two solar panels generate 40 V at 5 A as the voltages add up for an output of 200 W. Wired in parallel, the current is added up, and the system will deliver 20 V at 10A for an output of 200 W. A charge controller regulates the current and voltage to the battery to 14 V at 14.28 A.
The charge controller will convert the power generated by the solar panels and adjust it to the requirements to charge the battery. A 12 V battery charges at 14 V; thus, the charge controller will adjust the output current to 14.28 A to deliver 200 W of power to the battery.
The input power in Watt will be balanced by the output power in Watt to suit the battery charge parameter.
We will look at the effects of the following criteria:
- Solar panel orientation; Series or Parallel
- Battery Bank Voltage
- Charge Controller Protection
Let’s look at how charge controllers protect and balance the power output from the solar panels to charge batteries and power loads.
Where Does The Charge Controller Fit Into A Solar System?
A solar panel cannot be linked directly to a battery or battery bank, as this will cause damage to the most expensive element of the solar system.
The main cost elements of a solar system are the battery bank and solar panels.
The solar panels are pretty rugged and are designed to be robust to survive up to thirty years of exposure to the elements. The battery bank is expensive but will not last as long as the solar panels.
Even modern Lithium Ion Phosphate batteries will last ten to twelve years before needing replacement. For older type flooded batteries, the lifespan is much shorter.
The charge controller is used to right-size the power generated by the solar panels to charge the battery under the most optimal input voltage and charge current parameters.
Overcharge Prevention
Once the battery nears full charge, the charge controller will lessen the charge rate to prevent the battery from overcharging and getting damage.
It is important to note that charge controllers are not used in solar systems tied to the grid but only where there is a battery bank to be charged. The primary role is to protect the battery bank by controlling the charge rate.
Some charge controllers also have DC load control, connecting DC applications to the charge controller.
The charge controller can thus manage the charging of the battery bank and the supply of DC power to DC applications connected to the charge controller.
When the solar panels do not generate power at nighttime, the charge controller will prevent power from flowing from the battery bank to the solar panels and only allow power to the DC loads.
Charge Controllers Manage Multi-Stage Charging Of Batteries
The charge controller will manage the power flow to the batteries by monitoring the batteries state of charge (SOC). If the SOC is low, the charge controller will allow the full flow of power to charge the batteries at the optimal voltage and charge current.
As the charge controller senses the batteries fill up, it will slow down the rate of flow to charge the batteries to prevent them from being overcharged and overheated. Overcharging will cause the electrolytes in the battery to boil off, damaging the battery and significantly shortening its lifespan.
As the charge controller detects that the battery SOC is full, it will continue to trickle-charge the battery to maintain its optimal SOC. This multi-stage charging is what a charge controller is designed to perform.
Multi-Stage Charging Key Points
- Bulk Charging – Send all the available power from the solar panel to the battery bank in optimal voltage and current.
- Absorption Charging – As the battery bank charge builds up, it regulates the voltage and the current to taper down to safe charging levels.
- Equalization Charging (Flooded Batteries) – The high voltage is maintained, and periodic boosts will agitate the electrolyte and level differences between cell voltages.
- Float Charging – Keeps the voltage to the battery low when the battery is fully charged.
Single Or Multiple Solar Panels Requires Charge Control
A charge controller must always be installed between a solar panel and a battery bank. Two solar panels can be connected in series or parallel to the charge controller to adjust the voltage and current at which the battery must be charged.
Batteries and battery banks can also be wired to be 12 V, 24V, 36V, and 48V systems. The charge controller will control the power coming from the solar panels in such a way as to optimize the charging conditions for the battery bank.
Standard Voltage Charge
The solar industry has standardized solar panels with 60 photovoltaic cells with a nominal voltage of 20 V.
The VOC is the “open circuit” voltage that you will measure directly from the solar panel using a Voltage-meter, and the Vmp is the “voltage at maximum power.”
Charge controllers will sense the voltage generated in ambient conditions and adjust it to suit the battery charging conditions. A solar panel will be more efficient in cold weather and generate more power.
The charge controlled will balance the solar-generated power from the solar panels to optimally charge the batteries.
What Are The Different Type Of Charge Controllers?
There are three charge controllers in use today, of which the Pulse Width Modulated (PWM) and the Maximum Power Point Tracking (MPPT) are the most widely used. Simple shunt-type charge controllers have become redundant due to limited functionality.
PWM charge controllers are much lower in cost than MPPT and are good for simple systems with similar voltage input and output. The PWM charge controller pulse charges the battery at the same voltage it receives from the solar panels.
Wiring Series
To charge a 12 V battery, you must use a 12 V solar panel. To charge a 24 V battery bank (two 12 V batteries in series), you will require two 12 V solar panels in series. To charge a 48 V battery bank (four 12 V batteries in series), you need to wire four 12 V solar panels in series.
Ensure that the PWM charge controller is rated to handle the voltage of your battery bank system. The panel voltage must be in balance with the battery bank voltage.
How An MPPT Charge Controller Works
MPPT (Maximum Power Point Tracking) Charge Controllers are the most sophisticated and expensive, adding the most value to complex solar system setups. The MPPT tracks the optimum voltage/current ratio from the solar array.
An MPPT charge controller can increase charge controller efficiency by up to 30% over conventional PWM units, and more importantly, MPPT controllers can manage different input and output voltages.
MPPT charge controllers offer the best functionality when designing a solar system and higher voltages for long-distance power transmission when the solar panel array is far from the battery bank.
Connecting Solar Panels Together
Connecting solar panels together is a simple and effective way of increasing your solar power capabilities. Going green is a great idea, and as the sun is our ultimate power source, it makes sense to utilize this energy to power our homes. As solar power becomes more accessible, more and more homeowners are buying photovoltaic solar panels.
However, these photovoltaic solar panels can be very costly so buying them over time helps to spread the cost. But the problem then becomes how do we connect these extra solar panels together to increase the voltage and power output of what’s already there.
The trick here when connecting solar panels together is to choose a connection method that is going to give you the most energy efficient configuration for your particular requirements.
Connecting solar panels together can seem like a daunting task when you first start to look at how it should be done, but connecting multiple solar panels together is not that hard with a little thought. Wiring solar panels together in either parallel or series combinations to make larger arrays is an often overlooked, yet completely essential part of any well designed solar power system.
There are three basic but very different ways of connecting solar panels together and each connection method is designed for a specific purpose. For example, to produce more output voltage or to produce more current.
Solar photovoltaic panels can be electrically connected together in series to increase the voltage output, or they can be connected together in parallel to increase the output amperage. Solar pv panels can also be wired together in both series and parallel combinations to increase both the output voltage and current to produce a higher wattage array.
Whether you are connecting two or more solar panels, as long as you understand the basic principles of how connecting multiple solar panels together increases power and how each of these wiring methods works, you can easily decide on how to wire your own panels together. After all connecting solar panels together correctly can greatly improve the efficiency of your solar system.
Connecting Solar Panels Together in Series
The first method we will look at for connecting solar panels together is what’s known as “Series Wiring“. The electrical connection of solar panels in series increases the total system ouput voltage. Series connected solar panels are generally used when you have a grid connected inverter or charge controller that requires 24 volts or more. To series wire the panels together you connect the positive terminal to the negative terminal of each panel until you are left with a single positive and negative connection.
Solar panels in series add up or sum the voltages produced by each individual panel, giving the total output voltage of the array as shown.
Solar Panels in Series of Same Characteristics
In this method ALL the solar panels are of the same type and power rating. The total voltage output becomes the sum of the voltage output of each panel. Using the same three 6 volt, 3.0 amp panels from above, we can see that when these pv panels are connected together in series, the array will produce an ouput voltage of 18 Volts (6 6 6) at 3.0 Amperes, giving 54 Watts (volts x amps) at full sun.
Now lets look at connecting solar panels in series with different nominal voltages but with identical current ratings.
Solar Panels in Series of Different Voltages
In this method all the solar panels are of different types and power rating but have a common current rating. When they are connected together in series, the array produces 21 volts at 3.0 amps, or 63 watts. Again the output amperage will remain the same as before at 3.0 amps but the voltage output jumps to 21 volts (5 7 9).
Finally, lets look at connecting solar panels in series with completely different nominal voltages and different current ratings.
Solar Panels in Series of Different Currents
In this method all the solar panels are of different types and power rating. The individual panel voltages will add together as before, but this time the amperage will be limited to the value of the lowest panel in the series string, in this case 1 Ampere. Then the array will produce 19 Volts (3 7 9) at 1.0 Ampere only, or only 19 watts out of a possible 69 watts available reducing the arrays efficiency.
We can see that the solar panel rated at 9 volts, 5 amps, will only use one fifth or 20% of its maximum current potential reducing its efficiency and wasting money on the purchase of this solar panel. Connecting solar panels in series with different current ratings should only be used provisionally, as the solar panel with the lowest rated current determines the current output of the whole array.
Connecting Solar Panels Together in Parallel
The next method we will look at of connecting solar panels together is what’s known as “Parallel Wiring“. Connecting solar panels together in parallel is used to boost the total system current and is the reverse of the series connection. For parallel connected solar panels you connect all the positive terminals together (positive to positive) and all of the negative terminals together (negative to negative) until you are left with a single positive and negative connection to attach to your regulator and batteries.
When you connect solar panels together in parallel, the total voltage output remains the same as it would for a single panel, but the output current becomes the sum of the output of each panel as shown.
Solar Panels in Parallel of Same Characteristics
In this method ALL the solar panels are of the same type and power rating. Using the same three 6 Volt, 3.0 Amp panels as above, the total output of the panels, when connected together in parallel, the output voltage still remains at the same value of 6 volts, but the total amperage has now increased to 9.0 Amperes (3 3 3), producing 54 watts at full sun.
But what if our newly acquired solar panels are non-identical, how will this affect the other panels. We have seen that the currents add together, so no real problem there, just as long as the panel voltages are the same and the output voltage remains constant. Lets look at connecting solar panels in parallel with different nominal voltages and different current ratings.
Solar Panels in Parallel with Different Voltages and Currents
Here the parallel currents add up as before but the voltage adjusts to the lowest value, in this case 3 volts or some voltage value very close to 3 volts. Solar panels must have the same output voltage to be useful in parallel. If one panel has a higher voltage it will supply the load current to the degree that its output voltage drops to that of the lower voltage panel.
We can see that the solar panel rated at 9 volts, 5 amps, will only operate at a maximum voltage of 3 volts as its operation is being influenced by the smaller panel, reducing its efficiency and wasting money on the purchase of this higher power solar panel. Connecting solar panels in parallel with different voltage ratings is not recommended as the solar panel with the lowest rated voltage determines the voltage output of the whole array.
Then when connecting solar panels together in parallel it is important that they ALL have the same nominal voltage value, but it is not necessary that they have the same ampere value.
Connecting Solar Panels Together Summary
Connecting solar panels together to form bigger arrays is not all that complicated. How many series or parallel strings of panels you make up per array depends on what amount of voltage and current you are aiming for. If you are designing a 12 volt battery charging system than parallel wiring is perfect. If you are looking at a higher voltage grid connected system, than you’re probably going to want to go with a series or series-parallel combination depending on the number of solar panels you have.
But for a simple reference in regards to how to connect solar panels together in either parallel or series wiring configurations, just remember that parallel wiring = more amperes, and series wiring = more voltage, and with the right type and combination of solar panels you can power just about any electrical device you may have in your home.
For more information about Connecting Solar Panels Together in either series or parallel combinations, or to obtain more information about the different types of solar panels available, or to explore the advantages and disadvantages of using solar power in your home, then Click Here to order your copy from Amazon today and learn more about designing, wiring and installing off-grid photovoltaic solar electric systems in your home.
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I have read on the web that there should be a diode (blocking reverse flow of current) inserted between PV panels arranged in parallel. I have two small 12v panels (50W 30W) and I want to chain them in parallel to get 80W @ 12v. Do I have to put a diode somewhere in the wiring between the panels and the battery? Or just between the two panels?
Hi I have 4.2 kw controller(ups) and 8 solar panel of 545 watt each. each panel 48 volt. each panel current is 10 amp at its peak Now. i have a question How can i arrange these panels to get max output? If i put 6 panel in series and 2 panel in parallel then connect these together. what is my output ? I require max output Kindly guide me
hello some advice please i have 4 x 235w panels voc 37v rated 29.5v to power 4 x 130 ah wet battery bank wired series and parallel via a 100amp mppt controller and 24v 6000w invertor would i be better off wiring the panels in parallel or series thanks for your help and advice
Please I have 2 Panels 270Watts each, connected to a charge controller that charges a 12Volts 200AH battery. I just bought another 2 Panels 300Watts each to be connected together with the existing system. I am thinking if I pair 270W panel with 300 W panel in series before connecting them all in parallel will reduce the loss?
We expect that there would be very little difference in the I-V characteristics between your 270W and 300W panels, as there is such a small difference in wattage, 270W compared to 300W. Thus the Vmp and Voc voltages would be very similar. But the Imp and Isc values would be more different. Then 2 x 270W in one series string, and 2 x 300W in a second series string, with both strings in parallel. That way the voltages would balance out but you would still get different branch currents relating to the wattages.
Currently, I have a 24v system with 24v panels connected in parallel. I want to step down to 12v system without changing the 24v panels, I just want to buy one 12v panel and connect in parallel. 1) What is the effect of 12v panel besides reducing the voltage output of other 24v panels to 12v? 2) Would the 24v panels retain their qualities in case I return to the 24v system after a few years?
1) It does not work like that. Your output would be around 18 volts and your 24 volt panels would be feeding current directly into the smaller 12 volt panel due to such a large mismatch. 2) Probably not, as they would deteriorate over time anyway, and would see your 12 volt panel as the load
Ok. Can I step the 24v panels down to 12v using my PMT 12v/24v Charge control? I want to scale down to 12v without throwing my active panels into the bin.
Hi If I got 2 x 200w Omega OSP201 Panels connected in series VOC – 22.2; SCC(A) – 8,6; VMP(v) – 18; Max VMP – 8,11 Connected to 2×180 amp/h batt in Paralel with 2000w Pure Sine inverter and 20 Amp Solar control charger. Is it the correct way? Thank you, I’m following
I have 24 x 230 W 37 volt 7.8 Amp panels. In order to fit these panels into my all-in-one EGR 120/240 6000 inverter I have to have a 500 volt max. I believe the only way to meet the 500VOC max requirement, I would need to wire 12 panels in Series and 12 panels in Parallel giving me 12 x 7.8 = 93.6 amps and 37 volts in Parallel 12 x 37 Volts = 444 Volts and 7.8 Amps in Series Can I combine the 2 Arrays?
12 panels in parallel with 12 panels in series, No. 12 panels in one series string equals 444 volts, and 2 series strings in parallel (12S2P) equals 15.6 (7.8 7.8) amperes.
If I connect two 18v panels in series creating 36v output, then connect this array in parallel with two other 36v panels, if one of the 18v series panels is in shade, how will it affect the total output.
The connection solar Panels was useful to me, so I am saying thank you, and hope to learn more from you
Hi I have a few 70 volt solar panels and they are very low amperage, I want to Connect to batteries however don’t as yet have an inverter, how are inverters rated and are there inverters that will take high voltages and give 12volt battery Charging Outputs,? I see many 12 volt and 24 volt inverters but cant seem to find one that accepts 70 plus volts input, these panels were sold with LED lights and i was told to connect 3 lights to one panel and they will act as day time down lights but there is no voltage on the light fittings and was told less than 3 lights will be too little and the panels out put would blow them up, so I decided not to operate this way as it sounds unsafe instead I want to use the panels to Charge batteries but the High voltage output is Confusing as other panels I used had 6-12 volt output not 70 volts
It seems you are confused. Solar Charge Controllers, also called Battery Charge Controllers take the voltage and current generated by photovoltaic panel(s), and/or wind turbine generators and produce a standard output voltage of between 12 to 48 volts DC (depending on model) used to charge a single battery or a larger battery bank. The configuration and wattage of any connected pv panel, or array would depend on the DC input characteristics of the contorller. Inverters take the DC voltage and convert or invert (hence their name) it into AC mains voltage and power, either single-phase 240V or 3-phase for use in the home or to feed the incoming mains power. Thus you would have two different controllers, one to produce the required DC voltage, 12V, 24V, etc. from the panels and another to create the higher mains AC voltage for the home. Nowadays, there are all-in-one MPPT Solar Regulators or System Voltage Controllers which have both units within one controller. Again, the DC input and power rating of the regulator will decide how you configure your panels, or array.
Thanks for that one last question the panels are 67.9v at 1.07 amps and 72.5 watts how is the best way to wire them all in Parallel, or 3 in series 3 in series then both sets of 3 in Parallel? I am thinking all 6 in Parallel from my Understanding is there a calculation for the best size Battery or number of Batteries that this will Charge? Thank you for your assistance
If your panels are rated at 70 watts each, and you state you have 6. Then that gives a total of 6 x 70 = 420 watts. This 420 watts is ONLY available during “full sun” conditions, about 4 to 5 hours per day. Thus assuming 4 hours gives 4 x 420 = 1680 watt-hours per day. Since its a DC system, watts are equal to volt-amperes (VA) in this case. Thus you have 1680 VA per day max. Assuming a 12 volt system, that equates to 1680/12 = 140 amp-hours per day max. Assuming a 50% depth of charge per day, then you would need a 280 Amp-hour battery. That is, your battery discharges to 50% capacity each day, and your panels recharge it during the 4 hours of full sun. Clearly, system losses and efficiency are not considered here.
I have two 100ah 12v batteries connected in parallel. I have a 100 watt thunderbolt solar kit connected to both batteries. I plan to add another 100w solar panel kit. Should I connect each solar kit to both batteries or connect one kit to a single battery and the other kit to the other battery?
Solar kit implies panel and charge controller. Then it is not advisable to connect two or more charge controllers to the same battery terminals as they will compete against each other and the battery bank may not be charged or protected correctly. Instead connect all the pv panels to the input of one battery charge controller.
not connect in paralel,you just connect your batteris in series and connect the pannels in series in order to increase the current,your system will run perfectly
Incorrect information. Series connection increases voltage, not current. He has a 12 volt system, not a 24 volt system
Hi there,I have 2x 330w in parallel with 36v,20a output.Can I run this through a 24v, 20amp. 440 watt voltage inverter/dropper/converter??
Please bear with me, I man not a total newby, but I do still have a lot to learn about this… I am changing / adding to my RV solar system. It currently has a single panel that I think is 175 watt with a 30 amp PWM controller and 2 12-volt 100 AH RV batteries that were not properly maintained and need to be replaced. Controller and batteries will get changed out, as I change/add panels on the roof and upgrade the wiring to the controllers and battery bank. I want to build the system so I can add to it in equal increments as I discover just how much power I need and if needs change. (Unit not yet in my possession so I don’t know exactly how I will be consuming power.) My original plan was to build the system with three 200-watt panels and a 60 amp MPPT controller (or 2 panels and a 40 amp controller), keeping everything balanced and add to the system in these increments. I have plenty of room for controllers and batteries, with a fair amount of room on the roof and plan on using Tilt Brackets to maximize collector exposure This is where I fall down…. Panels in Series or Parallel? Parallel would give me 27 volts. Series would give me 81 volts. I would really like to stay with 12-volt system so I don’t have to change anything else in the RV, Can this be done with the higher voltage / lower current feeds from the panels? Will the controllers be able to take the higher voltage and adjust accordingly or should I go with the lower voltage and higher current? Also, I don’t yet know at what my Charger/Inverter is rated at so I may have to change that as well. At this point the only thing I have purchased is batteries that were removed from my previous RV’s system. These are FLA 6-volt GC2 batteries that were connected in series/parallel giving me 12 volts, 420 AH (allowing for a 50% draw-down), giving me 210 AH. I will eventually switch over to Li Batteries and add additional cells as the system increases I am considering 200 Watt panels, up to 2000 watts MAX. The manufacturers spec’s on these panels have a Voc of 27 volts, Short Circuit Current of 9.66 amps. In your opinion, would I be better to consider more panels with a lower wattage (100 watts) or continue with the 200 watt panels? This is a large RV and mostly Boondocking / Dry Camping expected for 1 night stays and up to 2 weeks or more. (I have a portable generator, but would prefer to use it only when necessary).
The size of chosen panels would depend on the available installation space as 2 x 100W panels would take up about 40% more area than one single 200W panel. The configuration of your 2kW array would depend on the DC input characteristics of your charge controller. Higher voltage and lower current would be the preferred option as lower current means smaller diameter cables. Your 60 amp MPPT controller may have a DC input voltage of 150VDC, then your panels Voc of 27 volts would mean 5 panels in one series string (5 x 27 = 135V) and two parallel branches (5S2P) giving a Isc of 19.32 amperes (2 x 9.66) for your 2kW (10 x 200W) array. Clearly, you would need to consult your charge controllers specifications first.
I have 12 – 250 Watt solar pannels. Voc 37.6 and Rated current 8.27 Amps I have a 80A MPPT solar charge controller wit a Max PV input 2000W (Max. PV Array OV). I Have 24V 3KVA, with input voltage 65-140VAC/95-140VAC. Wich would be the ideal way to set up the solar panels to produce the most for my battey bulk and inverter?
We assume you have bought the solar items you have bought for a reason because you have some knowledge or have been previously advised. If not or you have no idea what you are doing but want us to tell you. Clearly, a 250W panel is for 24 volt battery charging. Thus 2000/24 = 83 amperes as you have stated. Then you need a 48 volt system with 6 branches of two panels per string. This would give a maximum array Voc of 75.2 volts, and a maximum array current of 50 amperes.
I have two panel 545 watt and one panel 150 watt l have 2.8 kva inverter 24watt how I connect these panel serial or parallel.
Clearly with such a large mismatch between panels, you cannot use the 150W panel with the two 545W panels.
All is spoken and all is said ,but I just want to know we have six 150watts panels,a 60A charge controller and 4 200A batteries which right way would you recommend us to use in connecting the panels and the batteries /which installation style will give something that is better that we may be able to use a 240-300 volts inverter and 60 12volts bulbs
You have 6 x 150 watt panels. Then you have a total of 900 watts maximum at full sun, no matter how you connect them. 150W panels are for charging 12 volt batteries, thus their Vmp is usually about 18 volts. 3 x 18 = 54 volts plus 25% for Voc equals about 68 volts. If your 60A charge controller can handle a maximum DC input of 68 volts, then 3 panels in a series string, and 2 parallel branches (3S2P). If not, 2S3P. Your 12 volt light bulbs will require a 12 volt supply from the 12 volt batteries. Then your 4 batteries are connected in parallel.
If both solar panels (120w and 200w) have a charge controller fitted do I need to remove one of them to charge two 12v 105A batteries
Each panel can be used to charge a single battery. But as the characteristics of each panel is different, each battery will charge at a different rate.
or join the the wiring below the two controllers to the battery bank. in this way should one panel, controller or wiring fail, the other panel will carry the load
Hi I have 8 solar panel of 545 watt each. each panel 48 volt. each panel current is 10 amp at its peak Now. i have a question How can i arrange these panels to get max output? If i put 6 panel in series and 2 panel in parallel then connect these together. what is my output ? I require max output Kindly guide me
I have 3x 215 watt panels victron. using a 50amp victron controller i will be fusing a 50amp from controller to battery.can you tell me do i need to fuse each panel to controller or can i just use one fuse.which size fuse.plus what would you recommend series or parallel.many thanks.
215 watt panels are generally for 24v systems, thus have an output voltage of around 36 volts. 215w/36v equals about 6 Amperes. 3 in series equals about 108 volts (check panel specs for max Voc). If you controller can handle upto 120VDC input go series at 6 amps. If not 3 in parallel at 36 volts, 18 amps at full sun. For series, obviously one fuse. For parallel, one fuse per branch (panel) if you want, or just one for the whole set.
If I have two solar pannes of same voltage(18v×2) but different amperes(80w,120w) and I use two different charge controller on one battery of 150AH.will my connection add up as expected?
Introduction: DIY AUTOMATIC SOLAR CHARGE CONTROLLER
Today I am back with another project called DIY AUTOMATIC SOLAR CHARGE CONTROLLER.
It’s an automatic switching circuit that used to control the charging of a battery from solar panels or any other source. It’s a 555 based simple circuits the charge the battery when the battery charge goes below the lower limits, and stop charging when the battery reaches it’s upper limit voltage
Step 1: My Goal
“To make a cheap and efficient solar charge controller”
Step 2: Circuit
This is the driving circuit of the DIY AUTOMATIC SOLAR CHARGE CONTROLLER.
To make this circuit you need
NE555 IC with IC holder
One 2N2222 or PN222a Transistor
One 330 Ohm 100 Ohm resistors
Two 330 Ohm 1/5 w resistors(optional)
Two 10K variable resistor
two, 3-Pin PCB connector
Two capacitors(i am using.1uF,you can use any)
This is the finished circuit (Fig)
The 5v relay is the main component of this circuit; it’s an SPDT (Single Pole Double Throw) relay. It have one common (pole) terminal and 2 contacts in 2 different configurations. One is N.O (Normally Open) and other one is N.C (Normally closed)
In our case we connect the ve of the solar panel to the pole of the relay and ve of the battery to N.O when the battery is connected to the SCC (solar charge controller) the circuit check the battery voltage the voltage is less than or equal to lower limit the current is flows to the battery and battery start charging. When the battery voltage reaches the upper limit, the rely is activated and the current is redirect to N.C for dumping
Step 3: Calibration
After finishing the circuit you need to set the upper and lower limits. Batter calibration is required to avoid the overcharging and over discharging of the battery. I am using 12v as lower lower limit and 14.9v as upper limits. that means when the battery charge reaches the 12v battery start charging.wen the battery voltage reaches the upper limit or 14.9 volt.the relay is activated and circuit start dumping
To set the limits you will need a multimeter and a variable power supply or two power supplies. one with 12v and other one with 15v.first you will need to set the lower limit. for that set the voltage to 12v and connect it to the circuit. connect the ground weir to the conmen of the multimeter and touch the testing probe to the pin 2 of the 555 IC. Adjust the voltage by adjusting the VR to get 1.66 volte. Then set the voltage to 14.9v and touch the probe to the pin 6 of the 555 IC. adjust the voltage to 3.33v.check once aging.now over SCC is ready for use
Step 4: Wiring
The Fig show the wiring diagram of the SSC
First connect the ve from the solar panel to the centre pole of the relay then connect a red wire from battery to N.O of the relay. connect the –ve wire from the solar panel to the.ve of the circuit then connect the battery’s–ve to the circuit.
Step 5: Working
when the battery voltage is less than 14.9 v the it start charging by passing current through N.O of the relay. when the batteries voltage reached 14 volt its automatically switch the relay to N.C.if you are using solar panel you don’t need an dummy load to dump the excess power. you can add an extra battery to the N.C to harvest the excess power
Step 6: Moment of Truth
this is a quick video of the DIY AUTOMATIC SOLAR CHARGE CONTROLLER
Step 7: Thank You
I will give thanks to you Mr. Mike Davis. this DIY AUTOMATIC SOLAR CHARGE CONTROLLER is based on the his design. I just modified it a bit to make it more compact. I will give all credit to Mr. Mike Davis
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1 Комментарии и мнения владельцев
Please is this a PWM or MTTP charge controller
Also the 2nd wire outputting from 7805 is 5volts going to relay and also directly to Ground (Pin #1 of 555)?
The Relay is backwards on this diagram. When the Relay is activated the NO pins will close, not the NC, The Dump should be on the Normally Open, so when the relay is energized it will Dump out the NO pin that will be closed at that point.
I think relay connection is wrong.when the charging voltage coming upper limits relay is on and when its comes lower limits relay is off.
I tride this circuit but it is not working, Please share complete details.