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Solar PV farms are a
cheap source of renewable energy where the energy released
by the sun is harnessed as electricity by the solar
photo-voltaic panels and transmitted through the
transmission systems. Generation of renewable energy through
the solar photo-voltaic systems has gained popularity
steadily with the ever increasing number of such facilities
being installed worldwide as the costs of solar
photo-voltaic panels has kept downward trends. Generation of
renewable energy by the use of solar PV panels is one of the
cheap sources of renewable energy and such facilities are
100% recyclable on completion of their design/ contract
period with negligible effects on the land, surroundings and
the environment. These facilities are fully compliant
sustainable resources. Renewable energy generation through
the solar PV systems are quite popular in the province of
Ontario in Canada which has become a popular location for
setting up such renewable energy facilities. Strong growth
in this sector is led by the strong initiatives of the
Government of Ontario for sustainable development and it’s
extremely attractive rates offered for generation of
renewable energy through Ontario Hydro’s popular Feed-In
Tariff (FIT) Program. A large number of Solar PV Facilities
are already generating carbon free energy in Ontario while
many more are under various stages of development. Such
facilities typically vary from 3MW to up to 10 MW for
typical utility scale ground mounted systems though few
facilities up to 260MW have also come up. Roof mounted
systems generally vary from a few kilowatts to around a
megawatt, depending on the size of the building roof area.
The present official trend is to promote larger sized ground
mounted solar PV generating facilities up to 200MW instead
of smaller ones. Typical utility scale ground mounted solar
PV facilities usually comprise of solar PV panels mounted on
series of racking tables supported on foundations mostly
comprising of partially embedded steel pipes being the
cheapest and most practical option. The governing loads for
the foundations of these lightly loaded solar PV structures
are usually frost loads especially in areas comprising silty/
clayey soils where large adfreeze stresses develop due to
frost, resulting into uplift of foundation piles. Typical
winter conditions in Ontario are harsh with extreme frost
conditions in most areas which poses unique issues for
design and construction of such farms. Being a relatively
newer technology, the procedures, codes and standards for
design and testing of lightly loaded solar PV structures are
still being formulated. In the absence of any specific codes
and standards regulating the design aspects of these lightly
loaded solar PV structures with frost uplift being the
governing load in almost every case for Ontario, Canada,
frost heaving and its effects often create adverse
conditions for these structures thereby affecting the
production and continuous supply of renewable energy to the
cities and towns in vicinity who purchase this energy. Due
to larger depths of frost penetration in extreme winter
conditions, understanding the action of frost and related
development of adfreeze on these lightly loaded pile
foundations is extremely important. Many such Solar PV
facilities have experienced frost uplift of foundation piles
either during the construction phase or during its life
time. Rehabilitation of such piles affected by frost is also
a relatively newer issue with varied handling techniques
being followed. This paper investigates these unique issues
related with the uplift of the foundation piles of the solar
PV facilities and looks into the effects of uplift of the
piles along with suggesting various options/ methodologies
for rehabilitation of such piles affected by frost, which
are presented in this paper. The authors have been involved
in design reviews, pile selection/ design and pile load
testing in the majority of the solar PV farms either
operational or under construction in Ontario along with
being heavily involved with the rehabilitation of solar PV
farms affected by pile heaving issues.
Keywords: Renewable Energy, Solar PV, Racking Table
Foundations, Panel Tables, Solar Panels, Foundation Piles,
Rehabilitation, Frost effects
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