Page 79 - The Veterinary Laboratory and Field Manual 3rd Edition

48 Willy Schauwers

Figure 2.7 Generator. Photo: Dr Ziay
Ghulam, Dr Wahidullah Bahaer, Central
Veterinary Diagnostic and Research
Laboratory, Kabul, Afghanistan.

and use a generator (Figure 2.7) to ensure that the solar PV system, such as during the night,
work can continue. It is important to properly as shown in Figure 2.9. Solar PV only produces
maintain and monitor the solar panels, inverter electricity when sunlight is available. The output
and batteries, and to store oil and fuel to run of a solar PV system varies with its rated output,
the generator and to ensure that the generator temperature, weather conditions and time of the
is serviced and well maintained. day.

Design and installation
Solar photovoltaic (Pv) systems
Proper system design and installation are the
Introduction first steps required for sustainable on-site
energy systems. Off-grid energy system design
The sun delivers its energy to us in two main is quite complex and should typically be done
forms: heat and light. There are two main types by a trained professional. This paragraph does
of solar power systems, namely, solar ther- not attempt to provide instructions on how to
mal systems that trap heat to warm up water design and install a system, but rather covers
(mostly for domestic use), and solar PV systems some general principles and lessons learned
that convert sunlight directly into electricity, as from previous installations.
shown in Figure 2.8.
When the PV modules are exposed to
sunlight, they generate direct current (DC) elec- General principles
tricity. An inverter then converts the DC into Foremost, it is important to emphasize the
alternating current (AC) electricity, so that it can importance of doing a design. One-size fits
feed into the municipal power grid (grid-tied) or all approaches to health facility energy sys-
a battery (standalone, off-grid). tem procurement are rarely effective. A proper
Off-grid solar PV systems are applicable for design must be done by a professional (include
areas without connection to a power grid or input from several stakeholders), and should
with a poor energy supply. An off-grid solar PV be reviewed after system installation to check
system needs deep-cycle rechargeable batteries, whether assumptions made were correct and
such as lead-acid, nickel-cadmium or lithium-ion that it is operating as expected.
batteries, to store electricity for use under con- Consider using an energy audit template
ditions where there is little or no output from to collect information for the design process

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