Solar
How to Install and Understand
A Simple Solar Panel System
A Simple Solar Panel System
Okay, I finally gave up trying to find all of the info that 1. was easy to understand, 2. was a sound and simple design, and 3. was easy enough for most everyone to understand (okay, I said that twice). I have decided to put the info here myself and try to explain it the best I can.
Edit: I found a simple diagram of a 12 volt basic system that is below the first write-up. For a first time solar builder, it may be simpler to understand.
Edit: I found a simple diagram of a 12 volt basic system that is below the first write-up. For a first time solar builder, it may be simpler to understand.
This is a block diagram of a basic, stand alone solar panel system. It is wired with a 24 volt battery bank for higher efficiency (the higher the voltage, the fewer losses due to power drops in the wiring). For the time being, let's forget about all that and concentrate on the components of the system and how they are wired together.
The solar panels are shown at the top of the diagram. Note that they are wired as two banks of 4 solar panels in series. Wiring the panels in series will increase the voltage to the controller and placing two 4-panel sets in parallel will increase the current (amperage) to the controller.
The controller is shown as the black module just below the solar panels. It has the task of making sure that the batteries get charged and are not overcharged or damaged by the solar panels. It also does some regular housekeeping on the batteries to maintain peak efficiency and longer life. Controllers constantly monitor the static voltage of the batteries to determine the amount of charge that is to be applied at any given moment. Simple, cheap controllers just keep an eye on the voltage and disconnect the solar panels when a preset voltage is reached. More sophisticated controllers monitor rates, voltages, efficiencies, and the power available from the panels. The best type of controllers are called MPPT (Maximum Power Point Transfer) controllers. MPPT controllers allow you to connect much higher voltage panels to lower voltage batteries for faster charge times and will allow the panels to gather light for longer hours of the day. The MPPT controller takes care of making sure the output voltage and current to the batteries are correct.
The batteries are shown in the lower left corner (blue) and are usually deep cycle 6 volt golf cart or industrial led-acid batteries. The ones in the picture are shown as regular 12 volt automotive or marine type. Most all batteries that are the size of a large car battery will hold a little over 1000 watts of energy (if used over a period of one hour, it would be called 1000 watt hours) or 1 kilowatt (KW). The battery bank shown holds about 6 KW of stored energy or enough to run six 100 watt light bulbs for 10 hours.
Just to the right of the batteries is the DC to AC inverter. This changes the direct current (DC) from the batteries to household alternating current (AC) for appliances, etc.
Solar panel systems will generally get about 5 hours of useful sunlight per each full sunny day ( about 10 to 3 local time). The angle of the sun outside of this time window is too low to the horizon and has to travel through too much atmosphere to deliver enough energy to the panels for conversion to electricity. Using a solar array that is higher in voltage than the battery bank with an MPPT controller will extend the useful charging time to 6 hours or more due to the voltage being usable at much lower sun angles. A 1000 watt bank of panels would be enough to fully charge the battery bank shown in one day's time.
The solar panels are shown at the top of the diagram. Note that they are wired as two banks of 4 solar panels in series. Wiring the panels in series will increase the voltage to the controller and placing two 4-panel sets in parallel will increase the current (amperage) to the controller.
The controller is shown as the black module just below the solar panels. It has the task of making sure that the batteries get charged and are not overcharged or damaged by the solar panels. It also does some regular housekeeping on the batteries to maintain peak efficiency and longer life. Controllers constantly monitor the static voltage of the batteries to determine the amount of charge that is to be applied at any given moment. Simple, cheap controllers just keep an eye on the voltage and disconnect the solar panels when a preset voltage is reached. More sophisticated controllers monitor rates, voltages, efficiencies, and the power available from the panels. The best type of controllers are called MPPT (Maximum Power Point Transfer) controllers. MPPT controllers allow you to connect much higher voltage panels to lower voltage batteries for faster charge times and will allow the panels to gather light for longer hours of the day. The MPPT controller takes care of making sure the output voltage and current to the batteries are correct.
The batteries are shown in the lower left corner (blue) and are usually deep cycle 6 volt golf cart or industrial led-acid batteries. The ones in the picture are shown as regular 12 volt automotive or marine type. Most all batteries that are the size of a large car battery will hold a little over 1000 watts of energy (if used over a period of one hour, it would be called 1000 watt hours) or 1 kilowatt (KW). The battery bank shown holds about 6 KW of stored energy or enough to run six 100 watt light bulbs for 10 hours.
Just to the right of the batteries is the DC to AC inverter. This changes the direct current (DC) from the batteries to household alternating current (AC) for appliances, etc.
Solar panel systems will generally get about 5 hours of useful sunlight per each full sunny day ( about 10 to 3 local time). The angle of the sun outside of this time window is too low to the horizon and has to travel through too much atmosphere to deliver enough energy to the panels for conversion to electricity. Using a solar array that is higher in voltage than the battery bank with an MPPT controller will extend the useful charging time to 6 hours or more due to the voltage being usable at much lower sun angles. A 1000 watt bank of panels would be enough to fully charge the battery bank shown in one day's time.
Here is a much simpler system utilizing a 12 volt battery. I would still use a 24 volt (or higher) solar panel and connect it to an MPPT charge controller to charge the battery. The 24 volt panel will give up to an hour of extra charging time per day and with the MPPT controller it will be able to charge the batteries more efficiently.
The output of the charge controller is connected to the battery and handles all the battery housekeeping tasks automatically. A 12 volt DC to 120 volt AC inverter also connects to the battery and provides the required voltage to run household items.
Most inverters are a modified sine wave type that work well for lights, TV's, radios, etc. If you are planning to run a refrigerator long term off of an inverter, I would suggest a pure sine wave inverter to keep the motor temps in the refrigerator compressor section from getting too high. Sine wave inverters are not as quite as efficient as modified sine wave inverters and are usually only 85% efficient. A refrigerator will work with a modified sine wave inverter. Just monitor the motor temps on the compressor and you should be okay.
And now some videos to show you how others are doing this:
The output of the charge controller is connected to the battery and handles all the battery housekeeping tasks automatically. A 12 volt DC to 120 volt AC inverter also connects to the battery and provides the required voltage to run household items.
Most inverters are a modified sine wave type that work well for lights, TV's, radios, etc. If you are planning to run a refrigerator long term off of an inverter, I would suggest a pure sine wave inverter to keep the motor temps in the refrigerator compressor section from getting too high. Sine wave inverters are not as quite as efficient as modified sine wave inverters and are usually only 85% efficient. A refrigerator will work with a modified sine wave inverter. Just monitor the motor temps on the compressor and you should be okay.
And now some videos to show you how others are doing this:
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