Solar Power Buyer's Guide

Selecting the correct solar panel products for your home can be an extremely daunting task for the average person. If after reading this buying guide you are still not entirely sure which products you require in order to start using solar panels in your home, then please do not hesitate to contact us now so that our experts can assist you.

South Africa has an average of more than 2,500 hours of sunshine a year; with the total radiation reaching the land area amounting to roughly 1 kilowatt per square metre at noon on a sunny day. This is more than double the solar radiation output of Europe, making it one of the highest in the world and perfect for home solar panels in South Africa.

This buyer's guide will cover the following topics:

  • How do Photovoltaic solar panels (PV) systems work?
  • Types of home solar panel systems
  • Types of solar panels
  • Determining what size solar panel system you require
  • Solar panel installation
  • Benefits of a Photovoltaic solar panels (PV) system

1. How do Photovoltaic solar panels (PV) systems Work?

PV Solar panels are made up of a series of cells that convert sunlight directly into electricity (direct current). These cells are made from semiconductor material, usually silicon. Solar panel cells operate according to what is called the photovoltaic effect, ('photon - light, 'Voltaic' - electricity). In the photovoltaic effect, sunlight (or photons) strikes the surface of semi-conductor material, such as silicon, and then the energy penetrates the cell and dislodges electrons from the material's atoms. Certain chemicals added to the material's composition help establish a path for the freed electrons. This creates an electrical current.

A fully functional home solar panel system is made up of the following essential components:

  • Solar panels: These are often connected together in an array to provide higher power outputs and DC voltages.
  • Solar storage batteries: The electricity generated through the home solar panels is stored here.
  • Charge controller/ regulator: These prevent excessive discharge or overcharging which could damage the solar storage battery.
  • DC-AC inverter: Solar panels produce direct current (DC) and most appliances and equipment are designed to be powered by alternating current (AC). An inverter is used to convert the direct current from the PV solar panels or battery into alternating current which we can use in our homes.

It is important to note that ordinary incandescent bulbs should not be used with a PV solar panel system for the home as they drain power from the batteries much faster than energy efficient LED light bulbs will.

2. Types of Solar Power Systems

There are two types of Solar Power Systems that can be used in the home or the office, namely:

2.1 Stand-alone Solar Power Systems

These systems are designed to operate independently from the grid (Eskom).
Since there is no electrical energy storage (batteries) in direct-coupled systems, the load only operates during sunlight hours when the PV solar panels are hit by the sun; making these designs suitable for common applications such as ventilation fans, water pumps, and small circulation pumps for solar thermal water heating systems.
For the above reason, it is advisable to have solar batteries installed in the solar panel system so that power can be stored and used when there is no direct sunlight.

2.2 Grid-connected Solar Power Systems

Grid-connected PV solar panel power systems are designed to operate in conjunction with the grid (Eskom’s power supply). The main component in grid-connected solar panel systems is the inverter. The inverter converts the DC power produced by the PV solar panels into AC power which is consistent with the voltage and power quality requirements of the grid and automatically stops supplying power to the grid when the utility grid is not energized.
A bi-directional solar panel interface is made between the solar power system’s AC output circuits and the electric utility network. This allows the AC power produced by the solar panel system to either supply on-site electrical loads or to feed power back into the grid when the home solar panel system output is greater than the demand of power being used within your house at any time.

At night and during other periods when the electrical requirements in your home are greater than the solar panel system output, the balance of power required in your home is taken in from the electric grid. This safety feature is required in all grid-connected systems and ensures that the solar panel system will not continue to operate and feed back into the utility grid when the grid is down for service or repair.

3. Types of Solar Panels

There are 3 types of Solar Panels available, namely:

3.1 Monocrystalline Solar Panels

These solar panels are made of a large crystal of silicon. Monocrystalline solar panels are the most efficient with regard to absorbing sunlight and converting it into electricity; and thus do better in lower light conditions than other solar panels.

3.2 Polycrystalline Solar Panels

These are the most common solar panels on the market today. They look a lot like shattered glass as consist of multiple amounts of small silicon crystals. Polycrystalline solar panels are slightly less efficient than Monocrystalline solar panels but are less expensive to produce.

3.3. Amorphous Solar Panels

These panels consist of a thin film made from molten silicon that is spread directly across large plates of stainless steel or similar material. Amorphous solar panels are less efficient than the other two types of solar panels but are also the cheapest to produce. One advantage of amorphous solar panels over the other two is that they are shadow protected, meaning that the solar panel continues to charge while part of its cells are in a shadow. These work great on boats and other types of transportation.

4. Determining what size system you require

If you plan on tying your solar panels into the grid, then one way going about it is to just buy as many solar panels as you can afford right now and then simply sequentially adding panels to the system as you are able to afford them over time. Eventually you could end up with a fully operational solar panel system that is completely independent of the grid and providing you with free electricity. 

If you wish to completely disconnect your home from the grid, then there are a few steps that you will need to follow in order to find out about how many solar panels you will require to generate 100% of the energy used in your home:

  • Make a list of all the electrical appliances that you use in your home, how many watts each uses and estimate how many hours per day you use them.
  • Multiply the total watts by the hours used for each appliance. So for example if you use a radio for 2 hours a day while working out and it uses 14W, then you would multiply 14 by 2 to get a total of 28watts per day for the radio. Once you have done this for each item, add them all up to get the total sum of watts that you use in your house on a daily basis.
  • Determine the average amount of sunlight hours your solar panels will receive a day.
  • Now divide the total amount of watts used per day as you figured out in step 2, by the average amount of sunlight. If you use 3000 watts per day in your home and the average sunlight is 4.3 hours, then you would divide 3000 by 4.3.
  • This means you will need at least 698 watts of solar panels to get enough solar energy to power your entire house.

5. Solar Panel Installation

NB. If you are not technically inclined, then it would not be advisable to attempt installing a solar panel system in your home without any assistance from a professional. Sustainable.co.za has many approved partner installation companies who will be able to economically and safely install a solar panel system in your home for you.

There are three ways in which to install solar panels in your home, namely:

  • Ground Mounted Solar Panels
  • Roof Mounted Solar Panels
  • Thin Film Solar Panels

5.1 Ground Mounted Solar Panels

Ground mounted solar panels are fixed to poles that are cemented into the ground. There are a couple different options you can choose from if you decide to go with a ground mounted solar panel system, namely:

  • Static Mounted System

The most cost efficient ground mounted solar panel system is to just use a setup that points the solar panels towards the most effective direction for maximum sunlight exposure.

  • Active Solar Tracker

Solar Trackers have an optical sensor that follows the sun throughout the day and maximizes the energy absorbed by the solar panels.

  • Passive Solar Tracker

This is a slightly cheaper option than active solar trackers. A passive solar tracker system uses the sun's heat to move liquid from side to side within the tracker; allowing gravity to turn the solar panels to follow the sun without the use of motors, gears or controls. By using either type of solar tracker you'll help your solar panels get as much sun as possible throughout the day as it automatically points them in a perpendicular direction to the sun.

5.2 Roof Mounted Solar Panels

Solar panels can be mounted on many different types of roofs. Shingle roofs are the easiest to work whilst tiled roofs can be a bit more challenging.

5.3 Thin Film Solar Panels

Although thin film solar panels don't absorb the sunlight with as much efficiency as other solar panels, there are numerous benefits to installing these types of solar panels:

  • Unlike Monocrystalline solar panels, you don't have to mount the thin film solar panels on your roof. The thin film panels are literally glued onto the roof which means no holes. Putting holes in your roof can void your warranty and even damage it if it’s not done correctly.
  • Also, thin film solar panels don't weigh as much as other panels that contain large amounts of silicon with structural support.
  • Thin film solar panels work better than conventional panels in very hot climates. They also do a better job of producing energy at the beginning and end of the day during times of non-direct sunlight.

6. Benefits of a PV System

  • Solar panel power is a renewable form of energy, i.e. it won't run out like oil, coal and gas.
  • Once the initial cost of purchasing the panels is paid in full, the electricity it produces for the remainder of the solar panel system's lifespan (25 – 30 years) is absolutely free!
  • Photovoltaic solar panels can provide electricity for lighting and entertainment during blackouts
  • Solar panel systems provide a safer lighting option than candles and paraffin
  • There are no harmful emissions caused either through generating electricity or inside the home
  • The photovoltaic solar panel industry can provide up to 400% more jobs than the conventional energy industry

Conclusion

Yes, it can seem daunting having to select the correct solar panels and accompanying products to purchase for your home, however this guide should point you in the right direction. If you require any further assistance, please DO NOT HESITATE to contact us so that our experts can help you choose the correct solar panel system for your home.