Easy to Assemble “Plug and Play” Solar Power
The sun produces an enormous amount of energy and it will keep on doing so for the next 5 billion years. The best and most reliable way to harness this source of renewable energy is with a solar power system. A solar power system (A.K.A. solar energy system, solar generator etc…) contains components which generate, store and convert the energy from the sun. The basic energy system contains: A solar panel, solar charger controller, deep cycle battery and an inverter – The battery is charged by the solar panels and the charger controller regulates the charging process, to ensure the battery is not over charged. The inverter converts the low DC voltage (typically 12 volts) to AC and at higher volts of either 120 or 240 volts. Most household appliance operates off, of either 120 volts or 240 volts AC, depending on country.
Solar powered enery systems that can run home appliances, produce dangerous voltages. If you don't know what you are doing, then consult a qualified solar contractor or an electrician. When working with solar, remember, high voltage and current can kill or cause fires...
Wiring a solar energy system starts with first connecting the charger to the battery. The solar panel is the last component in the system to be connected. When the charger is powered up, it first senses the battery that is powering it. It's part of the boot process that's programmed into the charger's microprocesser. Once the charger has identified the battery voltage, i.e. 12 or 24 volts, the charger is then set to charge the battery that is connected. The solar panel can then finally be connected... There are currently 2 types of charger available: MPPT and PWM. The MPPT types can accept solar panel voltages of up to 240 volts and the PWM types generally accept the voltages no higher than the battery being charged. MPPT chargers are ideal where thinner and longer cable will be used. Higher voltages flow more efficiently through thinner and longer cable. MPPT chargers can increase the solar panels efficiency by 30%! MPPT chargers though, are more expensive than the PWM type. The PWM type chargers work great, provided that the cable is not too long. Lower voltages don't flow very well in extended cables as there will be great losses - That's why MPPT controllers are recommended where the cabling may be long.
The charger that's used in our examples (Further down, fig. 1) is the PWM type. MPPT (example below) controller types have the same wiring connections as PWM charger types, however, the panels in a MPPT controller system may need to be connected in series to increase voltage - A combination of both series and parallel can achieve both power and voltage requirements... Higher voltages flow more efficiently and with lower losses through extended cables with minimal diameters. So if the solar panel array was going to be a great distance from the energy system and long cables were used, then the best results for energy production would be achieved with higher voltages - Shorter distances don't care much for losses.
Solar panels connected in series to maximize voltage output... A typical MPPT controller setup.
It’s often best to buy the largest charger that you can afford for your energy system, so that upgrades can easily be made in the future, minus the added cost of buying a larger charger. For a basic energy system that can be used to power the fridge, TV, lights and kitchen appliances, I choose a 30 amp charger controller and a 2000 watt inverter – I choose a 30 amp charger controller, because I don’t intend for my system to contain more than 3 solar panels –That way, I can start with a single 120 watt solar panel and when applicable, I can then upgrade to a maximum of 360 watts for a 12 volt system or 720 watts for a 24 volt system of additional solar panels in the future.
The image below, are examples of a 12 volt system that uses a 30 amp controller.
Charging system without inverter...
Charging system with inverter...
Most solar charger controllers have 6 terminals – 2 for battery, 2 for solar input and 2 for 12 or 24 volt loads, depending on configuration. Since all the solar peripherals have 2 terminals (negative and positive) each, assembling a solar power system is simple. A 30 amp solar charger controller has a maximum power output of 360 watts for a 12 volt system, or 720 watts for a 24 volt system. So, for a 12 volt system, and 8 hours of sunlight, that system can produce approximately 8 x 360 watts = 2,880 watt hours a day and 5,760 watt hours for a 24 volt system. So what does that mean? Well, for the 12 volt system, you could use a battery with a capacity of; 2880 watts / 12 volts = 240 AH or 2 x 240 AH batteries for a 24 volt system. The 24 volt system would have 2 x 12 volt batteries connected in series to produce 24 volts. The charger in our example can operate off, of either 12 or 24 volts. The charger can sense if either 12 or 24 volts is being used in the system.
The images below are examples of a 24 volt system that uses a 30 amp charger controller...
2 x 12 volt solar panels connected in series...
A single 24 volt solar panel...
Connecting the solar panels to the system is simple, for as long as the proper terminations are used, i.e. MC4 connectors. With the proper connectors in system, upgrades is as simple as snapping a couple of plugs together! The solar panels are first terminated with the connectors. The female connector is wired to the positive terminal of the solar panel and the male connector is wired to the negative. Connecting 3 x 120 watt solar panels in parallel is accomplished by using 4 x “Y MC4” connectors. See example below:
"Y" MC4 connector configuration for 3 parallel connected solar panels - "S" represents "Solar Panel" or an array of solar panels.
MC4 connector types
Connectors and cables makes solar installation like child's play!
MC4, "Y" Parallel Connector
MC4 Parallel branch Connector
Below is a terminated 20 watt solar panel ready to be plugged straight into an energy system...
Notice the MC4 plugs?
2 x 120 watt solar panels are connected in parallel to double the power output of a 12 volt system -
Notice how easy connecting 2 solar panels in parallel is? Everything just plugs together easily!
Here are two 12 volt solar panels connected in series to double the volts...
This controller is ready to be plugged to a solar panel or an array of panels... Notice the MC4 connectors? The MC4 connectors are wired in the opposite orientation to the solar panels, for example; the male MC4 connector is wired to the positive terminal of the solar charger and the female connector is wired to the negative terminal - This allows the solar panel (or an array of panels) to be easily plugged into the system.
In a 24 volt system, a combination of series and parallel connections are utilized for 12 volt panels, or 24 volt panels can be connected in parallel, just like the 12 volt system ( see Fig. 1, 2, 3 and 4).
In retrospect, the solar charger in our example, can be configured for either a 12 or 24 volt system – For a 12 volt system, the load output could be used to power a 12 volt LCD TV or any 12 volt appliance – Other models may need an inverter. For larger loads, a 24 volt system with a 24 volt inverter is recommended.
Inverter connections -
Here is just a basic inverter wired into the system... The terminals can be connected directly to the battery or bank of batteries. If this was for a 24 volt system, then a 24 volt inverter will be needed - the one below is a 12 volt inverter.
In the image below, is an example on how to utilize the charger low voltage sensor, to turn off the inverter when the battery voltage is too low - This configuration can also be used where more current is required at the load output of the charger...
Putting together everything you have learned so far, you can setup your own energy system by using our examples. Remember to terminate all connections with the appropriate connectors - By doing so, you will save yourself many headaches. If you choose to use an MPPT charger for your project, then the instructions explained on this page can be applied - Just remember though, PV input for the MPPT controller will be higher than the battery(s) being charged. For example; 120 volts PV input, 24 volt battery bank.
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