POWER April 2016 - 42

OPERATIONS & MAINTENANCE
AC or DC?
Capacities of photovoltaic (PV) power
plants are typically given in terms of
direct current (DC) power. DC capacities
represent the maximum output of the solar
panels, which can vary substantially
from the maximum output from the inverter,
as alternating current (AC) available
for use. Throughout this article, DC
rating is provided.
have turned their focus to O&M and/or asset
management, many of them creating subsidiaries
or spin-off companies dedicated to this
new service business, " Brehaut said.
Insource or Outsource?
Considering the crowded market, arguments
can be made for performing O&M internally,
as well as for hiring a service provider, or
for combining insourcing and outsourcing.
Experts told POWER that entities that typically
consider the in-house option include
utilities with portfolio sizes beyond 100
MW or those looking to slash operational
expenses (like European PV generators facing
feed-in tariff cuts), as well as independent
power producers.
The consideration typically hinges on
the cost of O&M. And while cost is significantly
lower for solar PV than for any other
renewables, it varies wildly, depending on an
assortment of factors. Major variables influencing
the extent and cost of PV O&M range
from site characteristics and environment-
including the size of the system and type of
installation (whether it's roof-mounted or
ground-mounted, for example)-to the availability
of water. The scope of O&M service
and scale, meanwhile, determine labor and
infrastructure needs, as do the size and density
of the plants in a company's portfolio.
Yet, knowledge gaps remain. An expert
from the International Finance Corp. pointed
out that because few large-scale solar projects
have been generating beyond the end of
their design life, it's difficult to predict O&M
costs beyond a 25-year timespan.
Consider O&M from the Start
Whether or not O&M will be outsourced,
system owners should consider O&M during
design, engineering, and construction to help
drive the selection of low- or no-maintenance
alternatives, if available. This also allows owners
to make use of connected inverters for remote
testing and updates and provide access
to and clearance around equipment. Keeping
O&M in mind from day one will enable them
to apply the 2016-issued " IEC 62446-1:2016 "
42
Table 1. Major elements of PV O&M. Source: EPRI, 2010
Task
Preventative maintenance
Panel cleaning
Vegetation management
Wildlife prevention
Water drainage
Retro-commissioninga
Upkeep of data acquisition and monitoring systems (such as electronics, sensors)
Upkeep of power generation system (such as inverter servicing, balance-of-system
inspection, tracker maintenance)
Corrective/reactive maintenance
Onsite monitoring/mitigation
Critical reactive repairb
Non-critical reactive repairc
Warranty enforcement
Condition-based maintenance
Active monitoring-remote and onsite options
Warranty enforcement (planned and unplanned)
Equipment replacement (planned and unplanned)
b. Critical reactive repairs address production losses issues.
c. Non-critical reactive repairs address production degradation issues.
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Continuous
As needed
As needed
Notes: a. Retro-commissioning identifies and solves problems that have developed during the course of the PV
system's life.
Variable
As needed (high priority)
As needed
As needed
1-2x/yr
1-3x/yr
Variable
Variable
1x/yr
Undetermined
1-2x/yr
Frequency (typical)
2. Global megawatt-scale PV O&M and asset management competitive
landscape overview. This graphic illustrates the state of the market as of September
2015, naming its five biggest players. They include vertically integrated firms First Solar (4.3
GW), SunEdison (3.2 GW), and SunPower (1.8 GW)-all of which manage large North American
fleets. They also include Schneider Electric (1.9 GW)-just one of a number of inverter companies
(among them, ABB, Enphase Energy, and SMA) that are seeking O&M contracts-as well
as independent service provider WiseEnergy (1.5 GW). Courtesy: Megawatt-Scale PV O&M
and Asset Management 2015-2020: Services, Markets and Competitors (GTM Research and
SoliChamba Consulting)

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POWER April 2016

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