Page 21 - Blue Valley Issue 5 2021

ESTATE NEWS

Solar photovoltaic (PV) electricity has green, sustainable,
price increase protection and continuously available power
benefits. The answer to financial viability depends on the
intended use of solar PV.

combined return on the first and second In this case, the probable best alternative summarY
scenarios could see a return of investment would be a diesel or petrol electrical generator. The solution to a particular power user’s
within four to seven years. The capital costs could be lower but offset needs will lie somewhere between these
by the cost of fuel to replace the zero cost of scenarios or a combination of them. A key
sCenario 3: 24/7 PV eleCtriCitY sunlight. advantage of PV systems is that they can
WitH utilitY GriD baCkuP typically be migrated from one scenario to
The third scenario entails providing enough otHer ConsiDerations the next, provided this is borne in mind at the
energy storage for electrical supply all day, In the case where a user only wants to avoid outset. A consideration of the individual user
with the utility only providing minor short term power outages due to load shedding, cable or business requirements needs to be done at
demand excesses during the day or night. In this theft, failures, etc. and is not too concerned with the outset in order to find the optimal long-
case, additional panels are needed to ensure reducing electricity costs, serious consideration term solution.
sufficient PV energy is generated during the should be given to using a generator without
daylight hours to fill the batteries for the night any solar PV. Some of the key questions to consider are:
and some rainy days, as well as supplying the What is the current and future electricity
load during the day. It also entails sufficient The switchover from utility to generator could requirement by the hour of the day, day of
energy storage batteries for this purpose, if be manual or automatic. A further option in this the week and month of the year? What are
the utility is not available. A hybrid inverter is case is an uninterruptible power supply (UPS) the major electrical power users like a geyser,
also necessary for this scenario. The return on where the utility power charges a battery. The stove, aircon, pool, computers, machinery, etc.
investment for this configuration is typically UPS consists of a battery, inverter and battery in the same periods? How critical are these
seven to ten years. charger. The UPS then supplies power when the items if there’s no utility power or sunlight
utility power fails. The costs are typically low but available? Does the installation need single
sCenario 4: no utilitY or GriD the returns are usually not easily quantifiable. or three-phase power? What is the pitch and
PoWer aVailable – ComPlete The convenience of having power when needed orientation of the available roof space or other
inDePenDenCe is a major benefit. location of PV panels? How do we expect the
The fourth scenario is where the utility grid is price of utility electricity to change in future?
typically not available at all, such as in remote The choice of batteries and their initial and SA electricity prices are currently low by world
areas like farms. In this case, the solar PV and operating costs are important. Conventional standards.
storage needs to cater for the worst-case lead-acid batteries as used in cars, even deep-
scenario all the time. The inverter will be simpler cycle ones, come at a lower initial cost. However, There’s no cookie-cutter, one-size-fits-all
and less expensive. This will save some costs but they do not last very long when cycled daily solution and there’s no free lunch despite free
these would be more than offset by additional from 100% to nearly empty as is the case in PV sunshine.
panels and batteries to cater for the worst case. systems. The better alternative for PV systems is
lithium-ion (Li-ion) batteries. These cost more Interested readers are invited to make an
The return on investment would typically initially but last five to ten times longer in deep appointment to see a working home solar
exceed ten years, with the returns coming cycle systems like PV. Over eight to ten years, PV installation. Contact Neville Searle
from the economic benefit of having otherwise Li-ion batteries cost less than lead acid batteries at Blue Valley on 084 713 806 or email:
unavailable electrical power. in PV systems. searlenevillew@gmail.com

iSTOCK: ASphotowed

BLUE VALLEY NEWS • Issue 5 2021• 19