When planning your strategy to install a solar system and generating your own energy, it is essential to look at the size of the system you would want to and be able to install. There are many decisive factors to consider when determining the appropriate size for your system. Making sure your system is the right size to give you the ultimate output to meet your specific requirements, but still abiding by your constraints. Let’s look at the factors and constraints that will determine your system’s size and evaluate your options.
- Required output to meet your needs
- Peak sun-hours available to you
- Depletion of productivity over time
The size of your solar system will largely depend on the budget available to you. If your requirements are more than you can afford, you will have to opt for using a supplementary power source like Eskom, or start with a smaller system and build it up as your budget allows you.
Just as important is to measure the space that will be available to you. Evaluating the size is not merely looking at the surface space of your roof. In South Africa, your solar panels have to face north for them to be most effective in their production. It will also be necessary to figure out the average peak-hours of sun you will get in a day and at what angle your panels should be placed. This refers to the number of sunlight hours that the solar panels work optimally to generate the biggest amount of energy. In South Africa we are luckily blessed with sunny days, averaging between 5,5 and 6 peak sun-hours a day depending on weather and season.
Your desired output will influence the size of your solar system. The most accurate way is to make a list of all your appliances and note the number of Watts they need to function as well as the estimated number of hours they are in use. Multiply the two and you will have your average energy usage per day. It would be beneficial to have already optimised your home to be as energy-efficient as possible. When you have your average usage per day, take that number and multiply it by 1.25%. This is to account for the efficiency factor and the possibility of using an extra appliance. Let’s say your average usage is 1,5 kWh per day. Factoring the efficiency factor in would mean your average usage is 1,875 kWh. To establish the size of your solar system, divide your daily usage by the peak-hours available to you. If you get 5.5 hours of peak sunlight, your calculation would look like this:
1875 / 5.5 = 341W
This means that you will need a 350W solar panel. You should always round up.
Other factors that have to be looked at are the loss of efficiency over time, buying new appliances or wanting to expand, and wanting to use solar for only a percentage of your home. Sizing your system correctly can be tricky, especially when starting from scratch. We highly recommended making use of professional solar system installers.
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