Page 58 - Energize August 2022

TECHNICAL

opportunity to conduct research on PV
systems in a real-world environment.
We showed that the financial return on
investment is on track, with nearly half
the initial capital investment already
recovered through reduced electricity
bills. However, we also highlighted many
of the challenges we face with owning and
operating a variety of PV systems.

Did the fact that many of the CSIR’s
employees worked from home during the
Covid-19 pandemic affect the CSIR’s test
procedures? Figure 2: Single axis tracked system
The pandemic did not impact our
commercial business to any great extent. energy than panels on a fixed, horizontal plane (Figure 2). Panels on a dual-axis tracker will
Our team was busy developing the produce about 40% electrical energy. These results will vary with position on the planet and
quality management system for the lab according to the season. Panels on a dual axis tracker always face the sun, so the effective
in preparation for the SANAS ISO 17025 area of the panel for ‘catching photons’ is always maximised (Figure 3). The effective area
accreditation application which was of panels on a fixed tilt is reduced when the sun travels across the sky and the angle of
granted in September 2021. We were able incidence changes (Figure 4).
to do much of the paperwork remotely and
via conference calls. Business has picked up
significantly since the beginning of 2022,
and our team is back in the lab full-time.

Does the PV system at the CSIR generate
more than the Centre needs? If so, is the
surplus energy stored or lost?
The 2 MW of PV generates about 15%
of the annual electrical energy needed
to meet the demands of the main CSIR
campus in Pretoria. The CSIR consumes
all the electrical energy generated from
the system. We do have a small 2 kWh
storage system included in one of our
string inverters for demonstration that Figure 4: Static (fixed) rooftop system
automatically delivers electrical energy
when the sun goes down. If one million
South African homes were to install such
a system, then 2 GWh of stored energy
could be made available to the national
grid when it’s needed most. That’s a lot of
systems with high upfront costs, but the
potential is real.

How do PV panels on single-axis trackers
compare with those on dual-axis-
trackers? How do these compare with
static or fixed installations?
In Pretoria, panels on a single axis tracker
will produce about 20% more electrical Figure 3: Dual axis tracked system

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