Page 56 - Energize August 2021

TECHNICAL

Results
Figure 4(a) shows the variation of LCOE
(US$ cents/kWh) of the system along
with solar PV size (MWp) and the battery
capacity (MWh). The optimum range of
LCOE is represented inside the white
dotted circle. The optimum LCOE for the
complete power generation system was
found out to be about US$12 cents/kWh.
There are multiple system configurations,
i.e., combinations of solar PV and battery
capacity which can yield an optimum
LCOE. When compared, there is no
considerable difference between the
LCOEs of these different configurations Figure 4(a): Variation of LCOE with solar PV and battery size
represented inside the circle. Figure 4(b): Variation of RE-share with solar PV and battery size
The optimum installed solar range was
Parameter Optimum range Units
found out to be between 35 – 65 MWp
which translated to a solar-to-load ratio of Ratio of installed solar PV capacity per load 1,0 – 1,7 –
between 1,0 and 1,7. On the other hand, Battery full load hours equivalent 0,7 – 2,0 Hours
battery sizing range was found out to be RE-share (annual electricity generation) 30 – 40 %
20 to 60 MWh, which translates into the
Table 2: System sizing results for the base case considering current prices
battery’s full load hour equivalent of 0,7 to
2,0 hours. This assumes that the system can
handle all the grid stability limitations that it
might have when all engines are switched
off. Again, the objective was to identify the
overall economic potential of such system
while maximising the RE-share.
Figure 4(b) shows the variation of RE-
share with solar PV and battery capacity
with the optimal sizes represented inside
the white circle. It can be seen from the
figure that there is a steep increase in
RE-share from 10% to about 40% and Figure 5: Variation of LCOE with solar PV and battery size for (a) base case; (b) 15% cost reduction;
then the curve tends to flatten, reaching (c) 30% cost reduction
a saturation point. This saturation point
can be pushed further if the solar PV and Conclusions
battery capacity are increased, but only Large off-grid solar-battery-HFO hybrid systems can reduce the cost of electricity for the
until a certain level where any further total power generation by more than US$3 cents/kWh, allowing a renewable energy share
replacement of HFO in the system is only of up to 30% to 40%. There is a range of solar PV and battery configurations which lead to
possible through load shifting. similar optimum LCOEs, and the optimal size needs to be assessed on a case-by-case basis
The optimal system size range reaches reflecting the genset operational requirements.
between 30% and 40% share of renewable In addition, utilising cheap solar power in a fuel saver concept is not only attractive for the
energy to the overall power generation. mine operations to reduce cost of electricity, but also the reduction of CO 2 emissions.
The main results of the study for the base When looking at near to midterm future cost reduction potential for solar and battery
case are summarised in Table 2. When technology, the economically viable contribution of renewables in such a system exceeds
considering the battery and solar plants 50% while further reducing costs of electricity. Combining other renewable energy sources
near to mid-term future price reduction like wind could further improve the business case, which should be considered when
potential, the optimum range changes analysing a specific project location. n
significantly. A price reduction of 15% and
30% in solar PV and battery cost shifts the About Suntrace
optimum range towards larger solar PV Suntrace was established 2009 in Hamburg, Germany’s largest renewable energy cluster of
and battery sizes reaching more than 40% firms. http://www.suntrace.de
and over 50% of RE-share respectively, at
US$11,5 and US$11 cents/kWh as shown About Reuniwatt
in Figure 5. Reuniwatt is a major player in the solar radiation and cloud cover assessment and forecasting
In summary, RE-share increases while industry. http://www.reuniwatt.com
the LCOE for the overall power generation
cost including gensets decreases. Send your comments to rogerl@nowmedia.co.za

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