There is so much information that exists around solar, and with solar becoming more and more available to the consumer and for DIY projects, understanding how it works is a big first step to having your own solar project.
Solar Panels in the basic sense work by converting available sunlight into usable electricity. The way we define this power is by watts. Watts are made up of amps and volts. Different panels have different ratings for amps and volts, and it is helpful to understand what these numbers mean when you are looking at a system. You can imagine amps as the amount of electrons, and the voltage the amount of pressure pushing those electrons. Lear More
Equation: Watts = Volts x Amps
A solar panel is made up of different components as seen in Model1.1. Not all panels will have these specific components in the specific locations, but generally, our panels have this.
Solar Cell (a ): The solar cells can be seen on the front of the solar panel. They vary in color and appearance-based depending on the type of cell. The type of cell generally defines what kind of panel it is, for example monocrystalline, polycrystalline, amorphous, etc.
Frame (b): Most ACOPOWER Solar panels have an aluminum frame, but depending on the type of panel frame type can vary.
Junction Box (c): The junction box is generally located on the back of the panel. It contains bypass diodes to help with power loss due to shading. Also it serves as a connection and a holder for the panel wires.
Wire (d): Our ACOPOWER solar panels come with standard PV wire that is weatherproof and insulated (as long as there is no exposed copper wire).
MC4 (e): At the end of the PV wire is a MC4 connector. This MC4 connector is standard in the PV industry, is weatherproof and serves as a connection point to our other MC4 cable, such as an adaptor kit.
Specification Sheet (f): The panel’s specification sheet will tell you the electrical characteristics of your solar panel. It is very important when sizing systems.
MONOCRYSTALLINE VS. POLYCRYSTALLINE
Monocrystalline solar panels are slightly higher in efficiency than polycrystalline panels because each utilizes a different manufacturing technique. A monocrystalline cell consists of a single crystal ingot, whereas a polycrystalline cell consists of a growth containing multiple crystal structures. Both types of cells are made from silicon ingots, but the purity requirement of the silicon is higher on a monocrystalline base. Therefore, monocrystalline panels are more efficient, and thus, more expensive. By using a single cell, monocrystalline based silicon allows the electron greater freedom to move, so less energy is lost and higher efficiency is created. Most monocrystalline cells peak at 22% efficiency, whereas most polycrystalline cells peak at 18% efficiency. Monocrystalline cells are a dark blue almost appearing black, and polycrystalline cells are blue.
Even though this is true, there is a common misconception that monocrystalline solar panels will actually perform better than polycrystalline panels even in situations where they have the same wattage. This is not true. A 100W Mono Panel should perform just as well as a 100W Poly Panel, assuming the electrical characteristics are very close. A customer’s decision should be based on the price, the dimensions, and the color. Also due to common misconception, Poly and Mono panels should perform the same under low light conditions. They also should perform the same under high temperatures.
SOLAR PEAK HOURS AND IRRADIANCE
It is important to use the peak hours with the wattage of your system to calculate how many watt hours your system produces in a day. You can view peak sun hours as an average, as basing power off the hours of daylight during the day isn’t sufficient. The reason why is because sunlight in the morning and evening will not produce as much radiation as solar during midday. To calculate each states peak hours, the radiation is averaged based on the highs and lows and also other factors such as what is mixed into the atmosphere.
As you can see from the data gathered Model 2.1.2, the level of irradiance or W/m2 varies throughout the day. The panels output is directly related to the W/m2 at that given time. Most solar panels are rated at 1000 W/m2. If the irradiance level is let’s say 500 W/m2, like it is at 8am in the graph, then you should expect half the output (50%). Because of this fact, the solar peak hours of your state isn’t how long the sun it out, but an average from the lows and the highs so that it can be a reliable number in calculating energy generation.
12V VS. 24V PANELS
Panels come in compatibility of 12V and 24V, and you can wire them in various ways stay at 12V or wire them up to reach higher voltages. These methods are called series and parallel connections (which we will go into more later). A series connection will keep the amps the same, but increase the voltage. A parallel connection will keep the voltage the same and increase the amps.
Although we signify a panel as "12V", the panel doesn't actually produce 12V. The voltage the panel produces is greater than 12V, but this is necessary in order for the battery to charge. Batteries must be charged at a higher voltage than what they are nominal, as electricity will travel from higher voltage to lower voltage.
How you end up wiring your panels depends on the voltage of your battery bank. The voltage of your panels need to match the voltage of your battery bank in order for it to charge properly (with the exception of the MPPT controller which we will discuss later). Most RV and Boats have 12V battery banks, so usually customers stick with the 12V panels in order to be compatible with these batteries.
100 Watt 12Volt Monocrystalline Solar Panel
Peak Power(Pmax): This is how much power the panel is rated at the Standard Test Condition, which is 1000 W/m2.
Open Circuit Voltage (Voc): This is the panel’s voltage level when it is not hooked up to a controller and battery. It is important when sizing systems with controllers as panels will have this value for a short period of time when the system is hooked up. Also, this is important when troubleshooting a solar panel.
Operating Voltage (Vmp): This is the voltage level of the panel when it is set up and operating. This is important for calculating wire gauge size and wire length.
Operating Current (Imp): This is the current being produced when the panel is set up and operating. This is important for calculating wire gauge size, wire length, and controller sizing.
Short-Circuit Current (Isc): This is the panel’s voltage level when it is not hooked up to a controller and battery. This is important when troubleshooting a solar panel.
2. HOW TO SET UP SOLAR KITS
The complete solar kit consists of all the components that you will need to charge and discharge your battery bank. In this section, you will learn how to set up the complete system.
There are two types of solar kits: On-Grid kits and Off-Grid kits. Depending on your application and power requirements, you will choose one or the other.
On-Grid kits tie into your electrical company's grid and typically work best with larger applications such as residential and commercial buildings. These systems require professional installation and city permits. Commonly used for smaller applications such as RVs, vans, boats, and tiny homes, Off-Grid kits are user-friendly, DIY kits that require a battery bank as they do not connect to the electrical grid.
HOW TO SET UP
The first step in setting up your solar system is to determine which type of solar system is necessary for your application. If you are trying to power a house, cabin, commercial building, or a large-scale structure, it will be more practical to go with an on-grid system than an off-grid one. On the other hand, if you are looking to power smaller applications such as RVs, vans, boats, tiny homes, etc., an off-grid system tied to a battery bank is ideal.
The second step is determining the size of the solar system. For on-grid applications, your monthly electrical bill contains all your electrical usage information. Please email or give us a call here and we can size an appropriate system based off that information. Off-grid systems, on the other hand, require a little bit more work. To size a system that will best fit your needs, we recommend making a list of all the devices you plan on running. Get the wattage information, or the amps and volts of the product, and provide an average run time per device. With that information, we can size an appropriate system that will run effectively and efficiently.
The third step is setting up your new solar system correctly. For an on-grid system, it is necessary to contact your local electrical company to inform them that you are planning on going solar and contact a licensed installer/contractor for the installation of the system. They will be able to walk you through the rest of the process. For off-grid kits, we would recommend consulting with an installer, electrician, or our technical support team here for guidance and support. All our off-grid kits are DIY ready with a user-friendly installation process; all our installation guides are available online.
Once everything is set up, your system will start generating power as soon as the sun comes up. Please email or call our Renogy team here for any support.
3. ENERGY AND POWER
One of the most important concepts to understand when sizing a system or figuring out how much your panel produces is Energy and Power. Below you will be able to find a description about each along with some examples.
Power is defined as rate of doing work. It essentially tells you how quickly you can produce energy. Power takes on different forms, but when dealing with electricity or solar, you will define power as a Watt. As stated before, Watts = Volts x Amps. Multiplying the panel’s voltage by amperage will give you a wattage value. This is also true for an appliance. You can also think of power in terms of how much money you make hourly at a job, ie. $8/hour.
Energy is the capacity for doing work. It essentially tells you how much work can be done. Energy can take different forms, but when dealing with electricity or solar, you will define energy as Watt Hours. Watt Hours = Watts x Hours. Multiplying an appliances wattage, by how long it will run for will give you its energy value. Multiplying a panel’s wattage by the peak solar hours will give you its energy value. You can also think of energy in terms your paycheck, if you make $8/hour and work for 5 hours, you have $8 x 5 Hours = $40.
Energy in Panels
For Solar Panels, the energy produced is dependent on how much sun you get in your location. Sun hours will vary from state to state, but it is important to have an idea of what your state's peak solar hours are. For example, let’s look at a 100W panel in Texas vs. Nevada. Using Texas’s low value of 4.5 peak hours and Nevada’s low value of 6 peak hours we can calculate the energy or Watt-Hours produce by the panel. For Texas, 100 Watts x 4.5 Hours = 450 Watt-Hours. For Nevada, 100 Watts x 6 Hours = 600 Watt-Hours. As you can see the state location does have an impact on energy production, in this case by 150 Watt Hours.
ENERGY IN APPLIANCES
For appliances, the energy produced is dependent on the wattage value of the appliance along with the hours of run time. It is very important that you have the wattage, not just the voltage or amperage as those aren’t complete power values. For appliances, you can take the voltage and multiply it by the amperage. For example, an 8 Amp Fridge at 110V will be 8 Amps x 110 Volts = 880 Watts.
Let’s take two 35 Watt fans. One we will run for 2 hours and the other for 5 hours. The first fan consumes 35 Watts x 2 Hours = 70 Watt Hours and the second fan consumes 35 Watts x 5 Hours = 175 Watt Hours. As you can see, given the same fan, the second one takes more energy since it is ran for longer.
ENERGY IN BATTERIES
We can also relate energy to our batteries as well. Often times we get told that a customer has a 12V or 6V battery. As from what you saw earlier, this is not a complete form of energy, so just having this information is not enough to determine how much your batteries can store. We need to find the Watt-Hours value. Luckily most batteries are rated in a term called Amp-Hours. Although this has hours in it, it still isn’t energy. To get Watt-Hours we must multiply Amp-Hours by Volts.
Amp-Hours x Volts = Watt-Hours
For example let’s say we have two batteries, one 6V and one 12V. The 6V battery is rated at 100 Amp-Hours and the 12V battery is rated at 75 AH. The energy of the first battery is 6Vx100Amp-Hours= 600 Watt-Hours. The energy of the second battery is 12V x 75 AH = 900 Amp-Hours. As you can see even though the first battery has more Amp-Hours, it does not have more energy or storage.
Please view section （SYSTEM SIZING） on sizing systems to learn how to relate all of this together.
4. SOLAR ELECTRICITY BASICS
Knowing how to relate energy and power together is a very important concept, but it is also important to have a more in-depth understanding of electricity as well. This section will go over what electricity is made up of along with different forms of application. Learn More
CURRENT, VOLTAGE, AND WATTS
Current, Voltage and Watts are all related to electricity. Current is measured in amps. You can imagine current as the amount of electrons. Voltage is measured and volts. You can image the voltage being the amount of pressure pushing those electrons. More electrons or more pressure pushing electrons means more energy, just like more mass or more velocity for an object means more energy.
Just like you will need mass and velocity to calculate the power or energy of an object, the same is true with current and voltage. Just having one is not enough. Wattage is a measure of power in an electrical system, and is made up of amps x volts. Watt-Hours is a measure of energy in an electrical system and is made up of amps x volts x time.
ALTERNATING AND DIRECT CURRENT
Electricity by default will travel in one direction, which is called Direct Current, or DC. In a direct current circuit, electrons flow continuously in one direction from the source of power through a conductor to a load and back to the source of power. Originally electricity traveled by these means. The problem is, DC is not sustainable as it is hard to transfer electricity over large differences without power loses due to the low voltage level.
Eventually Alternating Current, or AC was discovered. An AC generator makes electrons flow first in one direction then in another. In fact, an AC generator reverses its terminal polarities many times a second, causing current to change direction with each reversal. AC can create a higher voltage level depending on how you utilize it. This provides advantages for utility companies to transfer electricity over hundreds of miles with little loss by utilizing over a million volts at times, since voltage travels easier than current. Eventually when the power reaches back to your house it is outputted to 100-120VAC, or sometimes 200-240VAC. Because of this, most household appliance are AC, and when you read the specification sheet, you will see the voltage in these ranges.
Now that you know the general differences, it is important to understand the difference of Power in Direct Current (DC) and Alternating Current (AC). Ignoring efficiency loses from either, power should remain relatively constant in both. For example, we can take a 200W TV and look at it in terms of DC (12V) or AC (110V). In terms of direct current the TV would produce 200W/12V = 16.6 Amps. In terms of alternating current the TV would produce 200W/110V = 1.8 Amps. Although the amp and the voltage values differ, the overall power is the same, so the rate of energy consumption, not counting efficiency loses, would be the same.
5. SERIES AND PARALLEL
This section will go into more depth on series, parallel and series-parallel connections. The purpose of this section is to explain why certain connections are utilized, how to set up to your desired connection, as well as going over what is the most beneficial connection to utilize based on your situation.
This section will go into more depth on series, parallel and series-parallel connections. The purpose of this section is to explain why certain connections are utilized, how to set up to your desired connection, as well as going over what is the most beneficial connection to utilize based on your situation.
Strictly parallel connections are mostly utilized in smaller, more basic systems, and usually with PWM Controllers, although they are exceptions. Connecting your panels in parallel will increase the amps and keep the voltage the same. This is often used in 12V systems with multiple panels as wiring 12V panels in parallel allows you to keep your charging capabilities 12V.
The downside to parallel systems is that high amperage is difficult to travel long distances without using very thick wires. Systems as high as 1000 Watts might end up outputting over 50 amps which is very difficult to transfer, especially in the systems were your panels are more than 10 feet from your controller, in which case you would have to go to 4 AWG or thicker which can be expensive in long run. Also, paralleling systems require extra equipment such as branch connectors or combiner box.
Strictly series connections are mostly utilized in smaller systems with a MPPT Controller. Connecting your panels in series will increase the voltage level and keep the amperage the same. The reason why series connections are utilized with MPPT controllers is that MPPT Controllers actually are able to accept a higher voltage input, and still be able to charge your 12V or more batteries. Renogy MPPT Controllers can accept 100 Volts input. The benefit of series is that it is easy to transfer over long distances. For example you can have 4 Renogy 100 Watt panels in series, run it 100 feet and only use a thin 14 gauge wire.
The downside to series systems is shading problems. When panels are wired in series, they all in a sense depend on each other. If one panel is shaded it will affect the whole string. This will not happen in a parallel connection.
Solar Panel arrays are usually limited by one factor, the charge controller. Charge controllers are only designed to accept a certain amount of amperage and voltage. Often times for larger systems, in order to stay within those parameters of amperage and voltage, we have to be creative and utilize a series-parallel connection. For this connection, a string is created by 2 or more panels in series. Then, an equal string needs to be created and paralleled. 4 panels in series need to be parallel with another 4 panels in series or there will be some serious power loss. You can see more in the example below.
There isn’t really a downside to series-parallel connections. They are usually used when needed and other options are not available.
HOW TO SET UP YOUR SYSTEM IN PARALLEL.
A Parallel connection is accomplished by joining the positives of two panels together, as well as the negatives of each panel together. This can be accomplished by different means, but usually for smaller systems this will be utilized via branch connector. The branch connector has a Y shape, and one has two inputs for positive, which changes to one, along with two inputs for negative, which changes for one. Please see picture below.
As you can see you have a slot for the negative terminal of panel #1 and the negative terminal of panel #2. As well as the positive equivalents. Then the negative out and the positive out will be utilized to connect to your charge controller via a solar PV cable.
Please see diagram below.
Let’s look at a numerical example. Say you have 2 x 100 Watt solar panels and a 12V battery bank. Since each panel is 12V and the battery bank you want to charge is 12V, then you need to parallel your system to keep the voltage the same. The operating voltage is 18.9V and the operating current is 5.29 amps. Paralleling the system would keep the voltage the same and increase the amps by the number of panels paralleled. In this case you have 5.29 Amps x 2 = 10.58 Amps. Voltage stays at 18.9 Volts. To check math you can do 10.58 amps x 18.9 volts = 199.96 Watts, or pretty much 200 Watts.
HOW TO SET UP YOUR SYSTEM IN SERIES
A Series connection is accomplished by joining the positive of one panel to the negative of the other panel together. With this you do not need any additional equipment except for the panel leads provided. Please see diagram below.
Let's look at a numerical example. Say you have 2 x 100 Watt solar panels and a 24V battery bank. Since each panel is 12V and the battery bank you want to charge is 24V, then you need to series your system to increase the voltage. For safety, use the open circuit voltage to calculate series connections, in this case the 100 Watt panel has 22.5 Volts open circuit, and 5.29 amps. Connection in series would be 22.5 volts x 2 = 45 volts. Amps would stay at 5.29. The reason we use open circuit voltage is we have to account for the maximum input voltage of the charge controller.
*If you want to check math it won’t work with the open circuit voltage. You can use the operating voltage, so 18.9 volts x 2 = 37.8 volts. 37.8 volts x 5.29 amps = 199.96 Watts, or pretty much 200 Watts.
HOW TO SET UP YOUR SYSTEM IN SERIES-PARALLEL
A series-parallel connection is accomplished by using both a series and a parallel connection. Every time you group panels together in series, whether is 2, 4, 10, 100, etc. this is called a string. When doing a series-parallel connection, you are essentially paralleling 2 or more equal strings together.
Please see the diagram below
As you can see this series parallel connection has 2 strings of 4 panels. The strings are paralleled together.
Let’s look at a numerical example for this diagram. This is mostly used on our ACOPOWER 40 Amp MPPT Controller as it can accept up to 1000 Watts of power, but only can accept 100 Volts in, which is why you cannot do everything in series. Paralleling 8 panels as well would cause too high of an amperage.
For this example, you would use the open circuit voltage of 22 Volts and the operating current of 5.71 Amps. Creating a string of 4 panels, you will have a voltage of 22 Volts x 4 = 88 volts, which is under the 100 Volt limit. Then by paralleling on the other string, the voltage will stay 88 volts and the amps will double, so 5.71 amps x 2 = 11.42 Amps.
* Keep in mind there is usually another factor that needs to be taken into account when sizing for the MPPT Controller called the boost current. This will be discussed in the charge controller section.
*If you want to check math it won’t work with the open circuit voltage. You can use the operating voltage, so 17.48 volts x 4 = 69.92 volts. 69.92 Volts x 11.42 amps = 798.49 Watts, or pretty much 800 Watts.
6. CHARGE CONTROLLER TYPES
This section will go over charge controller types and their purpose. We will look at the benefits of each controller and why one is better in a certain situation that another. We will also look at sizing different kinds of controllers. The charge controller is an essential component to every off-grid system. In fact, we do not recommend using an off-grid system unless you have a controller, and there are a lot of good reasons why. Charge controllers generally come in PWM and MPPT.
CHARGE CONTROLLER FUNCTION
The main purpose of the controller is to prevent the batteries from over charging. The controller directly reads the battery level, and once the battery is full, it knows to slow down the rate of solar charge to a float, keeping is from charging the batteries past 100%. This is important as overcharging the batteries can potentially ruin them.
Another purpose of the controller is to charge the batteries at the correct voltage level. This helps preserve the life and health of the batteries. Also, some controllers have special characteristics which allow you to wire your panels in a special way to achieve your charging goals.
PWM CHARGE CONTROLLER FUNCTION
PWM stands for Pulse Width Modulation, which stands for the method they use to regulate charge. PWM controllers have the more basic charging feature in the sense that they mainly just drop the voltage coming from the panel to charge the batteries. This drop in voltage equates to a loss in wattage, in the case of the PWM causing a 75-80% efficiency.
PWM CHARGE CONTROLLER SIZING
A PWM controller will have an Amp reading for it, for example 30 Amp PWM Controller. This represents how many amps the controller can handle, in the case above, 30 amps. Generally the two things you want to look at for a PWM controller is the amperage and voltage rating.
Please take a look at the following controller electrical specifications
Firstly we want to look at the system nominal voltage. This will tell us what voltage battery banks the controller is compatible with. In this case, you can use 12V or 24V battery banks. Anything higher, such as a 48V battery bank, the controller will not be able to work on.
Secondly we look at the rated Charge Current. We will use the above model VS3024AU in the chart as an example, in which case it has a 30 Amp rating. We recommended a factor of safety of at least 1.25, meaning you would multiply the current from your panels by 1.25 and then compare that to the 30 amps. For example, 5 x100 Watt panels in parallel would be 5.71 x 5 = 28.55 Amps. 28.55 Amps x 1.25 = 35.68 amps and would be too much for the controller. The reason for this is the panel can experience more current than it is rated for when insolation is above 1000 Watts/m^2 or tilted.
Thirdly we will look at the Max. PV Open circuit voltage. This tells you how many volts you can have going into the controller. This controller cannot accept more than 50 V in. Let’s look at having 2 x 100 Watt panels in series for a total of 22V (open-circuit voltage) x2 =44 volts. In this case, it will be ok to wire these four panels in series.
Fourthly we can look at the Terminals. Each controller will usually have a maximum gauge size for the terminal. In the case of the controller we are looking at, it can handle up to # 6 AWG. This is important when purchasing wiring for your system.
Fifthly we can look at Battery Type. These tells us what batteries are compatible with the charge controller. This is important to check as you don’t want to have batteries than cannot be charge by the controller unit.
MPPT CHARGE CONTROLLER FUNCTION
MPPT stands for Maximum Power Point Tracking, which stands for the method these use to regulate charge. MPPT charge controllers use this method of charging, which essentially finds out at any given condition, what is the maximum operating point for the panels current and voltage. With this method, MPPT controllers are actually 94-99% efficient.
MPPT controllers have two special features about them that will be mentioned in the MPPT Charge Controller Sizing section. One is that they can accept a high input voltage and step this voltage down to match your battery bank voltage for a correct charge. Two is that even though they lower the voltage, they are able to recover any potential lost power via a boost current, which increase the amperage to make up for the lost voltage.
MPPT CHARGE CONTROLLER SIZING
MPPT Controllers will have an Amp reading for it, for example a 40 Amp MPPT Controller. They will also have a voltage rating, but unlike PWM the input voltage rating is much higher than the battery banks it will charge. This is due to the special property of the MPPT controller being able to lower the voltage to the battery bank voltage and then increase the current to make up for lost power. You do not have to utilize the high input voltage if you want to avoid series connections in small systems, but it is very beneficial in larger systems.
Please take a look at the following controller electrical specifications
Firstly we can see, as we did before, that his controller can handle 12V or 24V battery banks.
Secondly, we will be looking at the MPPT-40, which is rated for 40 amps of current.
Thirdly we can look at the Max Solar Input Voltage, in this case 100 Volts. This particular MPPT Controller can accept 100 Volts input. It will then take this (up to) 100 Volts and step it down to your 12V or 24V battery.
Let’s take an example of a 400W system in series. You have 4 x 100 Watt panels, each with an open-circuit voltage of 22.5V. Those 4 in series will be 4 x 22.5 V = 90 Volts, which the controller can accept. Now if we ignored boost current, we would see that string only has 5.29 amps, so then if the controller is 40 amps, couldn’t we have (40/5.29 = 7.5) 7 strings, bringing us 2800 Watts? Why does the spec sheet say 520 W maximum? To answer this, we need the boost current.
Boost current can be calculated by taking the system array wattage divided by the battery bank voltage. In the case of 2800 Watts, we have 2800 Watts / 12 V = 233 Amps, which would destroy the controller. Realistically we find that 520 Watts / 12V = 43 Amps. We can ignore this result as 12V is a voltage you will probably never see. More accurately you would divide by boost voltage which is more common (you will learn about this in next section), so 520 Watts/14.4V = 36 Amps. We can now see why the boost current is an important part of sizing the controller.
Boost Current = Solar Array Wattage/Battery Voltage
CHARGE CONTROLLER MODES
As your panels charge your battery bank, your controller will adjust what voltage level they are being charged at based on the voltage level of the battery. These different voltage levels represent different charging stages.
Equalization charging voltage: An equalization voltage is one you will most likely never see. It occurs roughly every 20 days, and it temporarily over-charges your batteries to desulfate the battery cell. This helps with the battery cell health and allows them to last longer. In this case of the controllers in Model 2.5.3, the equalized voltage will vary based on the battery type you are using. In this case, you can also set the equalization voltage, which is beneficial for certain batteries that require a customer set parameter.
Boost charging voltage: A boost charge is a majority of what you will see when your battery is being charged. This is what does the majority of the job. As you can see it will vary from each battery type and in this specific controller the user can set their voltage level.
Float charging voltage: A float charge is used when the battery is full to prevent overcharging. A float charge will still charge a battery, but reduce the voltage and current equal to the batteries natural discharge rate, which depends on the battery bank size.
Low voltage Reconnect + Disconnect: This only applies to controllers that have a load terminal, which will be discussed in the next section. The low voltage disconnect is the battery voltage level at which the load cuts off. The low voltage reconnect is the battery voltage level where the load turns back on.
Outside of the things mentioned above, some controllers have extra features that can be utilized. I will go through each one.
Load terminal: The load terminal comes with some controllers and allows you to attach a DC load to the controller, rather than having to attach it to the battery. It is usually noted with a light bulb symbol as seen in Model 5. A lot of time this is utilized for the timer function. You can program the load to turn on at sundown and off at sunlight. This is particular useful for lighting.
LCD Display: An LCD display, as show in Model 9, can display different characteristics of your system and give you a more accurate portrayal of what is going on in your system than from the LED lights. This controller in particular will have icons that show what is happening in your system. It also displays numerical values for the voltage and amperage that your system is producing. Keep in mind, not all controllers have an LCD display and this is usually included on more expensive controllers.
RTS Interface: Connection for a RTS (Remote Temperature Sensor) to remotely detect battery temperature as show in Model 2
RS485 Communication interface: Monitor controller by PC, remote meter MT50 or APP and update controller software via RS485 (RJ45 interface) as show in Model 6
MT50 can display various operating data and fault of the system. The information can be displayed on a backlit LCD screen, the buttons are easy-tooperate,and the numeric display is readable.
We carry a variety of charge controllers each with different features that sets them apart from one another. When choosing which charge controller is right for you keep the following in mind. If you like to know what the system is producing throughout the day we recommend choosing the our MPPT charge controller with LCD Display or PWM ProteusX controller . If the controller will be mounted outside then the PWM ProteusX controller is the one for you. Our MPPT controller offer load terminals and a PC Monitoring Software. The PC Software allows you to customize the controller charging parameters and load terminal. We recommend MPPT controller or PWM ProteusX controller if you like knowing every little detail about your solar system. If you just want something simple without all these extra features ， the normal charge controller is your option. One of the most important features when choosing a controller is making sure it can charge the type of battery you have. All our controller are capable of charging Sealed, Gel and flooded batteries but if you will be charging a Lithium battery only the Voyager and Rover are compatible.
This section will go over battery types and their purpose. We will look at the benefits of each battery and why one is better in a certain situation than another. We will also look at sizing different kinds of batteries. The Battery Bank in the system is the main component in the system that gives you the capability to store and use energy.
The most important part of the system is the battery/battery bank, which stores the energy generated from your system. There are many different types of batteries on the market for various applications. Solar systems work with deep cycle batteries and not common cold cranking amp (CCA) automotive batteries. Deep cycle batteries can be charged and discharged at a slow rate and are ideal for solar setups. This section will talk about the purpose of each, along with how you would go about sizing them.
The main purpose of the battery is to store energy produced by the panel. Without this component, an off-grid system will be incomplete. Batteries are generally rated by a voltage level, mostly 6V or 12V, and an Amp-Hour rating. This Amp-Hours rating is important to know the capacity of the battery. Most small systems are 12V. RV and Boats generally are 12V systems as well. A set of batteries connected together is called a battery bank.
To understand battery sizing, we must understand the capacity of the battery. Batteries being measured in Amp-Hours and Volts, need to be calculated into Watt-Hours to tell you the energy. It is important to have both information.
Imagine you have 2 x 100AH batteries, one being 6V and the other being 12V. The 6V battery will be measured at 6V x 100 AH = 600 Watt Hours. The 12V battery will be measured at 12V x 100 AH = 1200 Watt Hours. As you can see even though they have the same Amp-Hours, their energy is different.
To size a battery, we need to first understand our consumption. We can calculate consumption as Wattage of Appliance x Hours of Run Time. Once we get this Watt-Hour value, we can divide it by 12V to get the battery in terms of Amp Hours. We also prefer to double this value, as we recommend a depth-of-discharge of only 50% to help preserve the life. This means we don’t recommend draining the battery under 50%.
Let’s take an example of a 35 Watt fan running for 6 hours. We have 35 Watts x 6 Hours = 210 Watt Hours. We then do 210 Watt-Hours/12V = 17.5 Amp-Hours. We then want to double the value for DOD of 50%, so we have 17.5 Amp-Hours x 2 = 35 Amp Hours. Our battery size would be 35AH at 12V. Keep in mind this is in 12V. To see this same battery in 24V, you would do 210 Watt-Hours/24V = 8.75 AH. You can then double this to 17.5 Amp Hours. This batter would be 17.5 AH at 24V. You can utilize multiple batteries in series, parallel, or series-parallel as mentioned in Section 5 （ SERIES AND PARALLEL） to get a desired battery bank size.
The most common battery type we recommend are Lead Acid Batteries. You will generally see a Sealed or Flooded Lead Acid battery. It is important to make sure that your controller is compatible with your battery type. We offer three types of compatible deep cycle batteries: AGM, Gel, and Lithium-Iron Phosphate. The AGM and GEL batteries have very similar characteristics whereas the Lithium-Iron battery is vastly different. We recommend researching the types to see which type is best for your application as they range in size, weight, and cost.
Once you choose a battery type and size, you can then start putting your system together. The battery is where all the energy is stored in the system and following all the safety precautions and guides is necessary. Please email or call our ACOPOWER team here for any support.
The inverter gives you the ability to run AC powered devices through your 12V battery. The inverter charger acts as an inverter and gives you the ability to charge your 12V battery from an AC power hookup. This section will talk about the purpose of each, along with how you would setup and run the inverter in your system.
You can choose different size 12V inverters and inverter chargers depending on your application and use.This section will talk about the purpose of each, along with how you would go about sizing them.
The purpose of the inverter is to convert DC to AC. Since batteries are DC, an inverter exists to allow you to run your AC appliances. They will come with an AC outlet to plug in things such as your computer, fridge etc. Inverters come in sizes of Watts, Volts, and can change DC to 100-120Volts, 200-240Volts, etc. It is important to make sure the voltage of your inverter matches the voltage of your battery bank.
The inverter charger acts as an inverter and gives you the ability to charge your 12V battery from an AC power hookup. We offer 500W to 2000W inverters as well as a 1000W and 2000W inverter charger.
When sizing for an inverter you need to look at 3 factors: wattage, DC voltage, and AC voltage.
Inverters will be rated by a wattage value, telling you how many watts it can run at one time. For example, imagine you had a 500 Watt Fridge and 800 Watt Air Conditioning. These two items would be 1300 Watts and would require an inverter with a higher wattage than 1300W.
The DC voltage rating on the inverter will tell you what battery bank it is compatible with. For example a 24V battery bank, will require an inverter that is compatible with 24V.
The AC voltage rating on the inverter will tell you what kind of AC appliances it will run. Most of the time a 100-120VAC(Volts AC) inverter will be ok as most household items come in that voltage. Sometimes very large loads will run on 200-240VAC so it is important to know this for special items you want to run.
The inverter size is solely dependent on what devices are going to be running on the inverter. If you are running multiple devices, then you will have to add the wattage consumption of those devices together. For example, if you want to run a television (800 Watts) and a Blu-ray player (400 Watts) at the same time, we would recommend adding those values together (800W + 400W = 1200W) and that tells you that you need an inverter that is capable of handling 1200W at the same time, so we would recommend going with a 1500W inverter.
Inverters come in modified and pure sine wave types. Modified sine wave inverters are usually much less expensive, but you are very limited to the amount of appliances you can use. Pure sine wave inverters are compatible with most devices, so we recommend going with these inverters.
HOW TO CONNECT
The inverter is separate from your solar system and does not require a solar system to run. The inverter runs directly off a 12V source and is very user-friendly to set up. Please refer to the unit's user manual for setup instructions and if you require assistance, please email or call our tech support team here.
Lastly, it’s important to be mindful of what is running through the inverter. Inverters are great for running AC devices on a DC battery but are not very efficient. Running most devices through an inverter will put a large drain on your battery, that's why it's important to keep track of what you're running and how long you are running them. With that in mind, you can now enjoy using your inverter to run your household devices through your battery bank.
This section will go over how to properly set up a basic system. We will make sure to include the inverter, battery, charge controller, panel and wiring in this set up.
SYSTEM SET UP
Note: When setting up your system, the panels should be out of the sun or covered for safety reasons.
First, the battery should be hooked up to the charge controller. You could use our tray cable or any general stranded copper core wire to connect the two. Make sure that you lead the wire into the battery terminal of the charge controller and match the + and – to the battery + and -. Make sure to screw in the exposed wire tightly inside the controller terminal. Then screw on the battery rings to the battery. See model 9.1.
Second, then connect your solar panel to your charge controller. We recommend that you connect the adapter kit to your panel first, then follow the + or – sign coming off of the leads of the panels and match it with the + and – sign on the charge controller. See model 2.8.2.
Be careful at this step, because if the panel is inserted incorrectly, you can have reverse polarity and short the system causing damage to the panels or controllers
Lastly, you can hook up your inverter to your battery by using battery ring cables and by matching the + to + and – to -.
See model 9.3 for more installation instructions
10. SYSTEM SIZING
This section will go over how to size your system. We will learn how to figure out how many panels and batteries you need, along with which controller and inverter will fit for your set up. Learn More
This section will go over how to size your system. We will learn how to figure out how many panels and batteries you need, along with which controller and inverter will fit for your set up.
Step 1: Load sizing
The first step to sizing your system starts with what loads or devices you want your solar system to run. It is important to get the wattage of each item you are planning to run along with how long you plan on running them for. You will multiply the watts by the hours to get Watt-Hours. If you have more than once appliance you just add them all together to get the total Watt-Hours.
Step 2: Solar Wattage Sizing
Next you want to find out what state you are located in. This will tell you the peak solar hours that you get from your state. You then want to take the load Watt-Hours and divide it by your peak hours to get Watts. This will be the Watts you need to run those items before efficiency loses occur.
Since your system will run through a controller, there will be efficiency losses. For a PWM controller you will have around a 79% efficiency and an MPPT will be around 94%. You then want to take the Watt value from before and divide/.8 it by the efficiency to get a new wattage value. If you are using an inverter, you want to do this again by dividing the value by 90%. You now have the wattage needed to run your appliances.
Step 3: Controller Sizing
Next, you need to find a controller that can accept the wattage you need. You can check the controller specification sheet to see the wattages they can handle. For example, a 30 Amp Controller can handle 400W on 12V, so you know you can have up to 400 Watts on there.
*If you want to size it by yourself, please reference section 6.
Step 4: Battery Sizing
In order to size your battery, you need to double your initial Watt-Hours value in order to make it so your loads only drain the battery down to 50%. You will take that last wattage value you calculated and multiply it by 2. You then divide it by the voltage, either 12V, 24V, or 48V based on what controller you end up using to find the Amp-Hours needed.
*If you want more details, please reference section 7.
Step 5: Inverter Sizing
To size the inverter you need to add up all the wattages of all the items you want to run. You then need to pick an inverter with more wattage than this. Also, make sure your inverter matches your battery bank voltage as well.
*If you want more details, please reference section 8.
a. Load Wattages x Hours = Watt-Hours
a. Watt-Hours / Peak Solar Hours = Watts
b. Watts/Controller efficiency = Watts
c. Watts/Inverter Efficiency = Watts Final
3. Battery Size
a. Watt-Hours/Battery Voltage * 2 = Amp-Hours
a. Inverter Size > Load Wattages