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Introduction to Solar Photovoltaic Systems

The idea of using solar photovoltaic systems is an attractive one to convert free solar energy into electricity for your property. With South Africa’s glorious sunshine, it’s easy to see why many home and business owners are looking to embrace solar energy and harness it by installing a solar energy system on their premises.

Main system components

The three main components of a solar power system are the solar panels to absorb solar energy, the inverter to convert that energy, and the mounting system to securely secure the panels. Other items you will need are switches, cables, meters and connectors. There is also a huge range of additional products available to optimize the PV system, such as batteries, optimizers, surge protectors, monitoring devices and much more.

How does a solar photovoltaic system work?

Solar photovoltaic panels convert solar energy into electrical current. Once installed, they should be positioned at the optimal angle and direction to optimize the amount of sunlight reaching them. Both residential and industrial sites are ideal installation locations. Sometimes even a large area can be a great opportunity to install ground-mounted solar power. When the panels are installed, they collect solar energy in the form of direct current (DC), and then a solar inverter converts it into alternating current (AC), which can then be used as electricity.

How much power will it generate?


The amount of energy will depend on where in the country the system is installed, and the amount of sunlight per year varies depending on latitude and other environmental issues. The table below provides examples of energy production per kilowatt of PV panel installed.

Location kWh/kWp
Bloemfontein 2055
Cape Town 1762
Durban 1570
Johannesburg/Pretoria 1871
Nelspruit 1766
Port Elizabeth 1698
Upington 2075

System size

The amount of energy produced is directly related to the size of the system and is calculated by multiplying the system size, defined in kWh, by the annual output figures from the table above. for example a 5 kW residential system in Johannesburg would need to generate 5 times 1871 kWh = 9355 kWh per year. The exact generation will depend on how close to north it is, how close to the optimal 30-degree slope, and any obstructions that might cause some shading.

Things to consider before installing the system

Is this location suitable for installing a photovoltaic system?

You’ll need to make sure you have the space, whether the system is installed on the ground or on the roof. Remember that skylights, chimneys, and roof overhangs will affect the number of solar panels you can install on that roof.

Is the roof structurally sound, and will installing PV compromise the integrity?

It goes without saying that a solar panel should never be installed on a roof that is not structurally sound, or that installing a solar panel would make it unreliable. It is also not recommended to install on a roof covered with asbestos. If you have any doubts, you should consult an expert for a survey.

How suitable is the object in terms of positioning?

To make the most of the sun in South Africa, it is best to install them on north-facing roofs. You can also sit facing northwest or northeast, however this is less effective.

What is the best angle to install?

This indicator is calculated individually depending on location. To be most efficient, solar panels should be installed at an angle of 25 to 35 degrees. Panels should never be installed horizontally.

Is the installation suitable for self-consumption using batteries or grid backup?

When it comes to utilizing energy the best way possible, many are looking to battery products, either to supplement their own self consumption, or as a reliable source of energy in the event of a grid failure. Any system using a battery source needs to be of a certain size in order to benefit the user. Some smaller systems would not be able to support an integrated battery.

What are the main incentives for home and business owners?

First of all, the owner will save on energy bills. Electricity suppliers are expected to steadily increase their prices as demand increases, with the potential for demand to outstrip supply. Using generated energy is a great way to save money.

If you are a solar installer, click here to learn more about the solutions SegenSolar can offer you.

Photovoltaics Explained

‘Photovoltaic’ is a marriage of two words: ‘photo’, meaning light, and ‘voltaic’, meaning electricity. Photovoltaic (PV) panels form part of a complete solar system to generate energy from sunlight.


Photovoltaic technology is the term used to describe the hardware converting solar energy into usable power. At the heart of this technology is a semi-conductor material which can be adapted to release electrons. The most common semi-conductor material used in photovoltaic cells is silicon — an element most commonly found in sand. Silicon is the second most abundant material on Earth!

Solar panels are comprised of a series of cells. All these cells have two layers of semi-conductors: one positively charged and one negatively charged. When light shines on the semi-conductor, the electric field between these two layers causes electricity to flow, generating direct current.

The greater the intensity of the light, the greater the flow of electricity. A PV system does not need bright sunlight in order to operate. It can also generate electricity on cloudy days. Due to the reflection of sunlight, days with slight cloud can even result in higher energy yields than days with a completely cloudless sky.

With South Africa’s long sunny days, PV technology is the perfect way to generate power from such an available (and renewable) source.

If you are a solar installer, click here to enquire more about the solutions SegenSolar could offer you. Alternatively, explore the range of photovoltaic panels available on the products page.

Solar Panels


A solar panel converts sunlight into electricity. They come in different sizes and colours with different solar cell types from various manufacturers.

Selecting a solar panel for a residential or commercial solar system requires understanding the different characteristics of each type of panel and the application.

On this page we explain some of the options and aspects to consider when selecting a solar panel.


Solar panels for grid-tied systems come in two main sizes, depending on the number of solar cells they are made from. 60 cell panels are about 1.6m tall and 1m wide, 72 cell panels area about 2m tall and 1m.

Larger panels are not better because they are bigger, they will generate the same energy on the same area of roof as smaller panels. i.e. the performance of 5 X 72 cells panels will be identical to 6 X 60 cell ones with the same energy and the same roof area. The choice is about which size of panel will best fit the available roof space.


The solar cells in a solar panel do not completely fill the area of the solar panel, there is a small gap around the end of each solar cell. Every solar panel has back sheet on which the solar cells are fixed and this backsheet can be white or black. A black back sheet looks better as it is closer to the colour of the cells but is slightly more expensive and will cause the solar panel to get hotter when it will be less efficient.

The frame of the solar panel can be silver or black. This does not impact on the performance of the solar panel but a black frame looks a bit nicer on the roof.

Cell Types

A solar panel is made using solar cells. Each cell is about 6 inches, 125mm, square. The cells are made using one of two different materials, monocrystalline or polycrystalline. Polycrystalline is slightly cheaper but is less efficient so a solar panel made with monocrystalline cells will generate more energy than one made using polycrystalline cells, but will be more expensive. Monocrystalline cells are also darker and so best used when you want a black back sheet for the best looking solar panels.


There are 100s of solar panel manufacturers in the world all of who will claim to make top quality panels that will last for 25 years or more. They will all offer a warranty of 10 years or more but it is important to select a manufacturer who you can be confident will still be in business in 10 years to honour that warranty.

With major world brands like Canadian SolarJA Solar and others you can be confident they will be around for the long term. Other smaller companies may not survive in the very competitive solar market. Often brand names you will see are not the actual manufacturer so it is important to find out who actually makes the panel and how secure they are as a business.

Between them the Top 7 solar panel manufacturers in the world made over 50% of the total panels made world-wide in 2017 and these form what is known as the Silicon Module Super League. It is highly recommended that you choose one of these brands to give you best the chance of long term reliability and performance.

System Types Explained

Although the principle is the same, yielding electricity from the sun, there are many ways that a PV installation can be installed to best suit the customer.

How to Determine The Size/Type Of System – Data Logging

To begin, in order for an installer to determine the best type and size of system, a period of power data logging at the target property will need to be undertaken using a power data logger like this one: http://www.meacon.co.za/Powersight/Data_Logger_PS2500.html

The Types Of System And Applications


Operating totally off the grid requires a large capacity battery array capable of powering the property during periods of low irradiance in winter and an inverter capable of supplying the maximum load ever required at one time. This requires a significant investment in PV modules, inverters and especially batteries which cannot normally be justified if there is a good quality grid connection available at the property. An off-grid system is well suited to rural areas with little or no grid connection but is unlikely to be a viable solution in a well-connected urban area. Should however fixed connection charges for electricity become more common and higher then disconnecting from the grid may become a more viable option in the future.


A pure grid-tied system with no storage or load management for a user with fixed rate power charges is a viable option for South Africa but the system will need to be significantly under sized to minimise the wasted energy generation as typically no surplus power can be exported. Essentially the PV system has to be sized to generate only sufficient power for the base load during the day, i.e. the fridge, freezer, pool pump and other permanently on devices. The low investment cost of a small PV system with a high self-consumption rate should make them quite attractive especially for households with family at home during the day.


If frequent load shedding continues each winter then there will be continued demand for grid-backup systems that can operate with no grid for prolonged periods of time. Adding a battery inverter or a hybrid inverter along with a battery makes it possible to combine the energy from the PV system with that from the stored battery to power at least the essential loads in the property. The size of the battery required depends on the rating of the essential loads to be driven from it at times of no solar power being available. Load shedding typically occurs during the evening peak in winter from 5:00PM – 10:00PM so there will normally be little or no solar power available to supplement the battery. Shown below is a typical system layout for a grid-backup system using a Solar PV inverter and a Battery Inverter which gives maximum flexibility in the system design and can be retrofitted to an existing Solar PV system:  An alternative solution for new installations is to use a combined PV and battery inverter, commonly referred to as a hybrid inverter. This is a multi-function device that includes all the functions required to configure a grid-backup solution:


Typically a residential system will generate the most power during the day when household consumption is not at the maximum. Without the ability to export surplus power the only options are to reduce the size of the PV system so that excess energy is minimised but this also reduces the usable energy or to store the energy until needed. A typical daily load profile for residential property is shown below;  With the above example reducing the size of the PV system by 50% would all but eliminate the surplus but would reduce the useful energy generated by 30%. The storage option could take the form of a battery system or using the surplus power to heat the hot water geyser. In the example above there is about 8kWh of surplus energy with could be used to heat the hot water with an insulated tank and/or recharge a battery for use in the evenings. Hot water heating is a very cost-effective option which with a correctly sized PV system could provide the best return on investment. A large battery solution may add significantly to the cost and would have a long financial payback time at current electricity prices. The use of a time switch on a washing machine and/or dishwasher can help to maximise the use of generated energy during the sunshine hours.


Many electricity users in South Africa, especially industrial, pay a very high tariff when they use higher amounts of electricity than normal during peak times. Some residential users are on tariffs which are higher during peak times of the day 5:00PM – 7:00PM or 06:00AM – 09:00AM for example or more for energy usage at any time above a certain threshold, e.g. 600kWh per month. In these cases a PV system may be used to limit the amount of higher cost electricity consumed by storing energy during the hours of sunlight and releasing it during the high cost periods. This may require additional timing controls to limit the time of usage of stored energy to these higher charge periods. The type and size of the battery is essential to any grid-backup or enhanced self-consumption system with many factors to take into account. Please read the SegenSolar Battery Guide for more information.

It is easy to see that South Africa could benefit from Solar PV. SegenSolar has stock of everything you will need for any of these installation types, will full pre and post sales technical support available if you need it. If you would like to enquire about a SegenSolar customer account, simply fill in the form here and one of our dedicated team will be in touch to help you.