What is solar?

The sun emits tiny packets of energy called photons; every hour, enough photons reach the surface of Earth to generate sufficient solar energy to satisfy global energy needs for an entire year.

When light hits a solar panel, it reacts with silicon crystals in each solar panel to produce an electric current – essentially creating its own power station. This electric current can then be converted into useful energy for powering your home or business.

Photovoltaic

What is photovoltaic technology?

‘Photo’ = light
‘Voltaic’ = electricity

Photovoltaic (otherwise known as PV) technology is the term used to describe the hardware that converts solar energy into usable power, generating energy from sunlight.

At the heart of this technology is PV panels. These panels consist of a series of cells which are usually made of silicon – the second most abundant material on earth. All these cells have two layers of semiconductors: one positively charged, and one negatively charged.

When light shines on the semi-conductor, the electric field across the junction between these two layers causes electricity to flow, generating DC (direct current). Inverters then transform this into a safer AC (alternating current) for use in your home or office.

The greater the intensity of the light, the greater the flow of electricity. But contrary to popular belief, a PV system does not need bright sunlight 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.

What is photovoltaic technology?

Photovoltaic

‘Photo’ = light
‘Voltaic’ = electricity

Photovoltaic (otherwise known as PV) technology is the term used to describe the hardware that converts solar energy into usable power, generating energy from sunlight.

At the heart of this technology is PV panels. These panels consist of a series of cells which are usually made of silicon – the second most abundant material on earth. All these cells have two layers of semiconductors: one positively charged, and one negatively charged.

When light shines on the semi-conductor, the electric field across the junction between these two layers causes electricity to flow, generating DC (direct current). Inverters then transform this into a safer AC (alternating current) for use in your home or office.

The greater the intensity of the light, the greater the flow of electricity. But contrary to popular belief, a PV system does not need bright sunlight 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.

Although the principle of harnessing energy from the sun is the same, there are many ways that a PV system can be installed. There are also several different factors to consider in order to determine which size and system will be best suited to your home or business.

For example, larger inverter models are ideal for commercial projects whilst roof furniture and any other sources of shading need to be considered when designing modules in a residential system.

There are three different types of PV system:

Off-grid

An off-grid system is well suited to rural areas with little or no grid connection. However, operating off-grid requires a significant investment in PV modules, inverters and especially batteries which cannot normally be justified in well-connected urban areas or properties where there is a good-quality grid connection available.

That being said, if fixed connection charges for electricity become higher and more common, 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 is a viable option for a user with fixed-rate power charges. The low investment cost and high self-consumption rate make a small PV system such as this especially attractive for households where family members are at home during the day.

However, the system will need to be significantly undersized to minimise the wasted energy generation as, typically, no surplus power can be exported. This means 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.

If frequent load shedding continues each winter, there will be continued demand for grid-backup systems that can operate independently for prolonged periods.

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 at your property such as the refrigerator, heating or air-conditioning and telephones. The size of the battery required depends on the rating of the essential loads.

Other systems:

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.

The storage option could take the form of a battery system or using the surplus power to heat the hot water geyser. Hot water heating is a very cost-effective option which could provide the best return on investment with a correctly sized PV system. The use of a timer switch on a washing machine or dishwasher could also help to maximise the use of generated energy during the sunshine hours.

In South Africa, many electricity users, especially businesses, pay a very high tariff when they use higher amounts of electricity than normal during peak times.

In these cases, a PV system may be used to store energy during the hours of sunlight and releasing it during high-cost periods – therefore, limiting the consumption of higher cost electricity. This may require additional timing controls to limit the time of usage.

To determine the best type and size of system for your home or business, a period of power data logging at the target property will need to be undertaken by an installer using a power data logger.

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Energy Storage

During the day, solar panels can capture more energy than a standard household can consume. However, with KODAK Storage Systems, you can store and save any surplus energy generated for use throughout the night, to avoid wasting any power. When the days are shorter over the winter months, this can be particularly beneficial. And, if you’ve still got enough electricity to keep your house powered, storage systems allow you to sell any extra power back to the grid!

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