Most homeowners that decide to adopt a solar system as a renewable energy source are buying a grid-tied system. This option makes sense when trying to save money, living in a municipality, and having an Eskom supplied energy grid available to you. Those living on a rural property like a farm or smallholding will have to decide on paying Eskom to put in a direct power line to their property or to adopt an off-grid power system. In many cases, it is much more feasible to adopt a renewable energy source system. With major improvements in technologies for solar and wind-powered energy sources, going off the grid has become more affordable and efficient than ever. So, let’s look at what an off-grid solar system is and how it works.
The components involved
A grid-tied solar system needs more components to function than a grid-tied system would need. These components are solar panels, a solar inverter, a battery inverter, batteries, a solar charge controller, a mounting and racking system, wiring, and junction boxes. Additionally, it is beneficial to have an alternative energy source, like a generator or wind-turbines, for when solar production is low.
Why do I need batteries?
The sun hits your solar panels and generates electricity as direct current (DC). It is then fed into a regulator that controls the amount of charge, recharging your deep cycle batteries. The DC electricity gets turned into alternating current (AC) by the inverter to be used in your home. When electricity is generated, you need to be able to store it. When you have a grid-tied system, the electricity gets stored in the power grid, but not so with an off-grid system. Batteries are needed to store the energy for later use when there is no sun to generate electricity.
During the evening, when no electricity can be generated, the system draws from the batteries to power your home. An off-grid system should meet your energy needs throughout the year, even in winter or rainy weather when sunlight is restricted. It is necessary to have enough battery capacity to meet these needs. Batteries are the most expensive component in an off-grid system and should be considered carefully.
What should I know about off-grid systems?
You will need to replace your batteries periodically. We advise that you do your research thoroughly to find out what types of batteries are available and the pros and cons of each. Lithium batteries, for example, only need to be replaced every 8 – 10 years. This is a big improvement from older types of batteries (like lead, calcium or AGM batteries) that have to be replaced every 3-5 years.
When you adopt an off-grid system, you will truly be independent of Eskom, meaning that loadshedding won’t affect you at all, while having a grid-tied system means you are still going to experience loadshedding. But it is important to consider getting a back-up system in case the primary system fails for whatever reason.
You will have to work out carefully how many solar panels you would need to meet your requirements and then ensure that you have enough space to accommodate all these panels. An off-grid system will need more solar panels than the average grid-tied system.
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