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Inverter
The PV
panels generate a DC voltage that requires conversion to AC
through an
inverter.
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The
PV
strings in my
system are connected to a
SMA
Sunny Mini Central 6000A inverter.
The "stock" photo shown above shows a Mini Central
inverter fitted with a plastic cover. Systems supplied
for the UK market, or at least mine, is fitted with a
grey, steel, cover. |
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The Mini Central can be fitted with communications modules
"piggy-backed" onto the inverter main circuit board to provide
access to inverter data. The "preferred" comms module uses
Bluetooth
communications to provide data access.
Sunny Explorer is a free software package which uses
Bluetooth communications to read data from the inverter.
However, I found that the steel cover seriously compromised the
range and reliability of the Bluetooth comms module to the
extent that Bluetooth was almost unusable for me.
Other comms modules are available, including an
RS-485 module
which also fits inside the enclosure but the RS-485 signal is
wired externally.
| SMA produce additional monitoring devices, including
the
Sunny Webbox. The Webbox is available in either
Bluetooth or RS-485 versions and provides TCP/IP access
to the inverter data as well as giving the ability to
upload data to the SMA
Sunny Portal internet monitoring site.
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| A limited subset of the data from my system uploaded to the SMA Sunny
Portal website are
here. |
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In the UK, if the system size is above 4kW (actually, 16 Amps
per phase), the
Distribution Network Operator (DNO) requires
that additional equipment is installed to protect the
National
Grid from disturbance in the event of any faults in your
generation equipment - a so called, G59 protection relay.
| My installer subcontracted the manufacture of a G59
relay protection panel. This panel used a
MainsPro unit manufactured by
ComAp in the Czech
Republic. The datasheet is
here.
This device was the most problematic in my system, until
rectified, a fault with the unit or an error in
its configuration resulted in frequent disconnection of
the inverter from the grid which reduced the efficiency
of the system when first installed. |
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