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Small scale embedded generation (SSEG) 

SSEG refers to renewable power generation under 1 Megawatt, located on residential, commercial or industrial sites. SSEG systems are connected to the wiring on the customer’s premises, which is in turn connected to, and supplied by, the municipal electrical grid - thus these generators are considered to be ‘embedded’ in the municipal electrical grid.

Most of the electricity generated by an SSEG user is consumed directly at the site. However, there may be times when generation exceeds consumption, and typically a limited amount of power is allowed to flow onto the municipal electrical grid. One of the major advantages of such a municipal electrical grid connected system is that it eliminates the need for backup batteries that stand alone (or off-grid) systems require.

Solar photovoltaic (PV) 

Solar PV panels that are mounted on the roof of a residential, commercial or industrial building are SSEG installations that convert solar energy into usable electricity. A PV system is made up of solar cells that are connected in a way that points them toward the sun, which an inverter then converts from direct current (DC) into usable alternating current (AC).

The size, layout and configuration of a solar PV system will differ, depending on the use of the system, size of the building, the energy demand and consumption pattern (load profile) and the ability of the municipal electrical grid-operator to allow the system to feed back onto the municipal electrical grid.

Many municipalities across the Western Cape already have the rules and tariffs in place for feeding into the grid when installing a PV system. The remaining municipalities across the province are being supported by the Western Cape Government and GreenCape to design and implement appropriate feed-in tariffs and approve the necessary regulations. To find out which municipalities have the necessary legal framework click here

It’s important to note that feeding-in requires permission from the municipality. However, installations that are off-grid don’t require permission.

What PV can and can’t achieve for a consumer 

It’s important to remember that PV is not an all-encompassing solution to the current energy crisis. The table below outlines what a PV system can and can’t do:

PV does: PV doesn't:
Provide price security for customer. Stop load shedding
Provide electricity supply security for customer. Reduce peak demand. There’s a misalignment between peak PV generation (midday) and average peak demand (early morning and late evening), unless battery storage is installed.
Provide additional supply in supply- constrained areas. Protect against rising cost of peak-time energy, unless battery storage is installed.
Promote changes in the customer load profile, thus adding options for other energy security options.
Support Eskom with room for maintenance by removing some of the demand on their systems.
Add diversity to the South African energy mix.

 

Components 

A complete PV system consists of the physical equipment and the additional resources to install and maintain the equipment. The table below outlines the components required:

Equipment Resources
The solar panels/modules A company to install the system.
Roof mounting structures; Periodic cleaning of the panels.
Special electrical cabling A meter management solution (municipality) to track energy consumption and generation.
An inverter i.e. a power device that converts direct current to alternating current at a voltage and frequency which enables the generator to be connected to the municipal electrical grid.
A meter to measure the energy generated (this is a municipal requirement, and only needed for municipal electrical grid- connected systems)
Optional battery storage

 

Solar PV system layout 

The figure below provides an indication of the layout of a solar PV system:

 

The costs 

The cost of installing a solar PV system is driven by the following elements:

  • the solar panels,
  • the inverter, and
  • the balance of system costs (installation and commissioning and project development).

The equipment components of the solar PV system make up the majority of the overall cost, with the solar panels and the inverter accounting for almost 80% of total costs. The installation, commissioning and project development account for the remaining 20%.

 

Rooftop solar PV installation for homes and businesses

Source: Content kindly provided by the Energy Sector Desk at GreenCape. For more information please visit http://greencape.co.za/