SA Affordable Housing September - October 2019 // ISSUE: 78 | Page 21

SOLAR POWER
FEATURE
A solar cell to an array of solar panels and the typical components of a solar system.
“If one is using electricity to pump the water flow, the energy
consumed by the pump will offset some of the advantage of
using solar thermal power, reduce the gains one is making,
and lengthen the payback time. However, the addition of
solar photovoltaic pumps would mean that they are entirely
running on renewable energy,” says Bredenkamp.
Photovoltaic (PV) solar panels – the technology most people
think of when they say ‘solar panels’, are devices that
convert sunlight into electricity. The system consists of solar
panels to absorb and convert sunlight into electricity, a solar
inverter to change the electric current from DC to AC, as well
as mounting cabling and other electrical accessories to set up
a working system.
The question always arises as to what will happen if the
sun does not shine for an extended period, or what happens
at night when there is no energy from the sun? By including
a battery storage system to the PV installation, one can
overcome this problem for at least a portion of the time.
However, this solution comes at a cost, which should be
included in the original loan from a financial institution.
The good news is that the cost of batteries has decreased,
and the technology has increased battery life, but living ‘off
the grid’ is not practical or affordable by most homeowners.
There are three classifications of rooftop PV systems and, in
South Africa, currently only option 1 (below) is available in
urban environments, as disconnecting from the grid would
not remove the monthly charges to the homeowner by the
local utility.
1. Grid tied / connected with reverse power blocking - the
property is connected to the national grid in order to
www.saaffordablehousing.co.za
PROMISE OF PV POWER
Many people assume that solar is related to solar thermal such as
this flat-plate solar hot water system, however it also includes
electricity generation through photovoltaics, or vice versa.
receive electricity, but any surplus electricity generated
by the system is prevented from being directed back into
the grid.
2. Grid tied / connected – electricity generated can be used
at the property and any surplus can be directed back into
the grid. In some cases, this feedback is compensated for.
3. Off-grid / standalone – the PV system generates
electricity for use on-site and operates completely
independent of the national grid.
VERIFICATION OF PV SYSTEMS
What is needed, and has now been introduced, is quality
control on the systems installed on people’s houses,
SEPTEMBER-OCTOBER 2019
19