Page 17 - Issue 4 2023

TECHNICAL

Rooftop PV system developments

Load shedding and the general poor security of supply of grid power, together with rising costs,
have led many commercial and industrial users to consider alternative sources of energy to

improve energy security.

By Mike Rycroft, Energize

ooftop or on-site solar, combined characteristics, and problematic warranty and maintenance issues. Systems available
with storage, offers a solution today offer a fully matched and co-ordinated, modular integrated design from a single
Rand the industry has responded source, that allows optimal performance and single warranty and maintenance points
with solutions specifically aimed at this of contact. Also, the systems allow the co-ordination of smart features to give overall
market. performance optimisation and improved operation and safety.
Commercial and industrial rooftop Driven by industry policies and technology advancement, distributed PV has
systems have special requirements witnessed vigorous development in recent years. The main challenge is how to
in addition to the usual technical improve the utilisation of rooftop resources and ensure PV plus ESS system safety, and
issues. The placement of solar panels, a high yield. Figure 1 shows the layout of a typical system.
conversion equipment and storage Developments are taking place in all three areas: PV modules, inverters and storage
systems in commercial and industrial systems.
(C&I) and residential properties brings
with it a new set of demands. PV module developments
Here, development is focused on the use of power electronics at module level. In
Safety a PV system, module-level power electronics (MLPE) refers to power electronic
Malfunctioning solar PV and energy equipment that can perform refined control on one or more PV modules, including
storage systems (ESS) can cause damage micro-inverters, power optimisers and disconnectors. MLPE brings unique values
to property and injury to persons, so such as module-level power generation, monitoring and safe shutdown. As PV
increased safety is a prime requirement. systems are required to become safer and more intelligent, the penetration rate of
The trend is to mount panels MLPE in the distributed PV market is expected to increase.
directly on the building’s roof and
to make maximum use of available Micro-inverters
roof space. Sometimes, panels are These are miniature inverters sized to suit individual solar panels rather than a string
installed without optimum orientation of solar modules. They have the advantage of allowing each panel to operate at its
and elevation, and in the case of optimum point independent of the other panels, and maloperation of one panel does
multiple roofs, different strings could not affect other panels.
have different orientation, i.e., face Continued on page 20
in different directions. This poses a
problem with maximum power point
control (MPPT) systems and would
normally require separate strings and
separate MPPTs for each roof string.
This increases the number of inverters
or the number of strings that an
inverter can handle, and requires a new
type of inverter and a new approach to
system component design.
Until now, grid connected PV and
storage systems comprised components
from different sources, often resulting
in a less-than-optimal match of Figure 1: Integrated solar PV and ESS power system

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