Learning exactly how off grid works can be tough considering there are a vast number of ways to design the systems. For clarity, we will explain the most common systems being installed in detail and then explain how the less common systems differ.
How off grid power works: AC Coupled
AC Coupled systems are the most advanced off grid system on the market. It is ideal for medium residential, large residential, and commercial systems. Below is a list of how the energy makes its journey from the sun to your application:
- Solar panel converts the suns energy in to DC electricity. This is done by semiconductors inside the solar panel that react to sunlight.
- Desired Voltage – Solar Panels are wired end to end to create a desired voltage. This wiring method is called a “string.” In a string circuit, solar panels will add their voltage while their current stays the same.
- Desired Power – We can use the one string or add more to increase the POWER output. For example, if we have 12 x 250watt solar panels in our string, we have an accumulated power of 3000 watts. So if 9000 watts were desired we would add 2 more string for a total of 3 strings.
- Inverter – The DC output of our solar panels is fed to a Solar Inverter where the DC electricity is inverted in to AC electricity. AC electricity is the common type of electricity found in our homes and businesses.
- The power from the solar panels is fed directly to the loads for the project. Any excess electricity is fed to the inverter/charge controller unit that is separate from the solar inverter.
- Inverter/Charge Controller – This unit has a lot of task and is the brain of the system.
- Battery Bank – The battery bank stores this excess energy from the solar. This energy is supplied back to the inverter/charge controller during night time or intense cloud cover.
- Inverter/Charge Controller (Again!) – Stored energy from the battery bank is inverted from DC back in to AC electricity. The AC electricity is fed to the loads for the project. In the event of extended battery use a generator can be controlled by the inverter/charge controller.
- Generator – A generator is usually coupled with off grid systems to run loads and recharge batteries.
How off grid power works: AC Coupled – Charge Controller (Outback – Midnite – MorningStar – Magnum)
The main difference in these systems is the placement of the battery bank in the system. In return this creates design restraints for larger systems. These systems work great for smaller applications.
- Solar array is configured for desired voltage and power as before. Only this time the string will be limited to a smaller voltage, requiring more strings.
- The charge controller conditions the solar DC to the Battery Banks DC voltage (typically 12, 24, or 48 Volt).
- The Battery Bank then feeds an Inverter.
- From here the system is identical as the inverter feeds the loads. Generators can be utilized in these systems as well.