Page 38 - Energize October 2021

VIEWS AND OPINION

documented processes, while others may offset on the utility bill. This means that at some point in time, the solar PV system may be
accept or reject applications through email producing more power than your load can take. In this scenario, the solar PV system can
communication. either reduce production (throttle/curtail) to meet the demand or utilise the excess energy in
other ways.
3. How much solar energy do I need?
A grid-tied solar PV system is usually designed 5. What can I do with excess solar energy?
to meet the typical daily peak load, and off-grid You can store excess solar energy in batteries which can be used at other times. Another
systems would typically be four times that size. If option would be to push back any excess energy that your solar PV system generates onto the
your tariff has a maximum demand portion, your grid. Some municipalities (such as the City of Cape Town) will pay you a predefined feed-in
monthly peak demand (kVA) readings or Notified tariff. Feed-in tariffs are often lower than your energy rates, so it usually doesn’t make sense
Maximum Demand (NMD) can provide rough to increase your system size just for the sake of feeding power into the grid. Alternatively, net
estimates of how big your peak loads are and will metering offers businesses the possibility to push any excess solar energy back into the grid,
enable a solar EPC (Engineering, Procurement which will then be offset against your energy consumption at the end of each month. Lastly,
and Construction) company to do a preliminary banking allows surplus energy from net metering to be “banked” at the end of each month
design with this high-level information. with the utility provider, which can then be used in months to follow (up to one Eskom annual
Datalogging the load will provide critical billing cycle).
information (typically in 30-minute intervals)
which enables a more accurate calculation of the Payment options for your solar plant
optimal size and forecast savings achieved by the Outright capital purchase of a solar PV system returns the most significant financial savings
solar PV system. Typical commercial and industrial but may negatively impact the cash flow of your business. This model allows the purchaser
solar PV systems range from 30 kW to 1 MW, the to own 100% of the solar system together with all the financial savings it generates. Power
current upper limit for SSEG capped by legislation. Purchase Agreements (PPAs) or Roof Rental Agreements will allow business owners to
authorise the installation of a solar PV system on their roofs by an IPP (Independent Power
4. What if I have too much solar? Producer) from which they can then buy power at discounted rates over a fixed term (usually
Solar PV systems are often slightly overdesigned 20 years), yielding savings from day one without any capex.
to cater for reduced power production in
winter and losses associated with equipment Contact Yolande Young, IMPOWER, Phone 021 300-0470, info@impower.solar,
degradation to maximise the amount of energy www.impower.solar

HOW A PV SYSTEM WORKS

Image source - FSEC Energy Research Center

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