Solar 101 – The Basics
A typical solar installation consists of the following main components (excluding fitment hardware, cabling and monitoring hardware and software):
- PV modules (groups of PV cells), which are commonly called PV panels;
- One or more batteries (also referred to battery banks if lead-acid batteries are used);
- A battery controller;
- An inverter;
When the sunlight comes into contact with PV panels an electrical field is created, transforming sunlight into electrical energy. This electrical energy is stored in batteries, managed by a battery controller.
An inverter converts the directed current (DC) stored in the batteries into alternating current (AC) so that we can run electrical appliances.
Three basic types of solar installations are possible:
A Grid-Tied electrical system, also called tied to grid or grid tie system, is a semi-autonomous electrical generation or grid energy storage system which links to the mains to feed excess capacity back to the local mains electrical grid. When insufficient electricity is available, electricity drawn from the mains grid can make up the shortfall. Conversely when excess electricity is available, it is sent to the mains grid. When batteries are used for storage, the system is called battery-to-grid (B2G).
Off-Grid is a system and lifestyle designed to help people function without the support of remote infrastructure, such as an electrical grid. In electricity, off-grid can be stand-alone power system or mini-grids typically to provide a smaller community with electricity. Off-grid electrification is an approach to access electricity used in countries and areas with little access to electricity, due to scattered or distant population. The term off-the-grid (OTG) can refer to living in a self-sufficient manner without reliance on one or more public utilities. Namely the electrical grid (e.g. Eskom). People who adopt this lifestyle are called off-gridders.
Solar Hybrid power systems are hybrid power systems that combine solar power from a photovoltaic system with another power generating energy source. A common type is a photovoltaic diesel hybrid system, combining photovoltaics (PV) and diesel generators, or diesel gensets, as PV has hardly any marginal cost and is treated with priority on the grid. The diesel gensets are used to constantly fill in the gap between the present load and the actual generated power by the PV system.
Most municipalities in South Africa does not have the infrastructure or is simply ill-equipped to deal with excess energy from solar installations, leave alone being able to give you credit for any excess energy that you may have available. Check with your local municipality if they can deal with you as a potential energy supplier.
NOTE: Grid-Tied solutions, in the South African context, simply means that you will supplement shortfalls from the grid. So, and until further notice, wherever this website makes mention along the lines of ‘selling back to the grid’ or ‘receiving credit for energy pushed to the grid’, it refers to countries that have matured to this level of sophistication, which does not include South Africa just yet.
First things first - Before you embark on your solar project, download this very handy Configurator to establish your Solar Needs first (Microsoft Excel 2016 workbook format). It also contains a host of other very useful worksheets that will assist you in your renewable energy quest.