Debugging and verifying microinverters for photovoltaic installations
Debugging and verifying
microinverters for
photovoltaic installations
by Win Seipel, Agilent Technologies, Inc., Santa Clara, CA
Traditional solar energy
installations use a single
centralized inverter to convert
the DC output from multiple
solar modules into AC power.
Enphase Energy uses a different
approach: The Enphase
microinverter system employs
one microinverter for each solar
module in the installation.
Enphase engineers use Agilent
E4350B and E4360A solar
array simulators (SASs) in
the development environment
to verify power production of
its microinverters and test the
voltage compliance range. They
also use an SAS to develop
and test the efficiency of
their maximum power point
tracking (MPPT) algorithms.
In the product verification
environment, Enphase uses
the solar array simulators to
ensure its products meet spec
and to simulate environmental
conditions for lifecycle testing.
!
In a solar power installation, an inverter module is shaded, the adjacent module can
converts DC power from photovoltaic be running at its maximum power point.
cells into grid-compliant AC power. The Enphase parallels the outputs of single
Keywords: Microinverters,
inverter’s maximum power point tracking inverters together in one or more branch
Solar Array Simulators, MPPT
(MPPT) circuitry and algorithm allow it to circuits and connects those circuits into
extract the maximum power available from the load center. According to Enphase,
a module over a wide range of environmen- this integrated system maximizes energy
tal conditions (see sidebar). harvest, increases system reliability,
Traditional designs use a single and simplifies design, installation and
centralized inverter to convert the DC management.
output from multiple solar modules Enphase design engineers use a device
into AC power. Enphase Energy uses a called a solar array simulator (SAS) to
different approach: Its system employs debug solar arrays on their lab benches.
one microinverter for each solar module They also use the SAS for product
within an installation. The inverters are verification and certification testing, and
independent and isolated, so even if one when developing MPPT algorithms.
8 – Global Solar Technology – July/August 2009
www.globalsolartechnology.com
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