21
Installation Manual
3.1.2. TIPS FOR SUCCESS (CONTINUED)
CTs
CT placement, orientation and wiring is very critical to successfully commission
the system. If CT are not correct the system WILL NOT COMMISION. CT are are
tested during commissioning "System Verification," "Meter" check. Taking a few
precautionary steps as outlined below will assist the installer with most of the
common CT issues.
•
CT Placement 1: CT1 must be place on L1 as connected at the inverter.
Hint
, use a voltmeter when the grid is on and the inverter is connect to check
that it reads zero VAC from main utility entry point L1 to the inverter's L1
connection. If it measures 240 VAC reverse the CTs, as the CT placement is
incorrect.
•
CT Placement 2: the CTs must read the same current as the utility meter is
reading. This includes seeing the current from the inverter's grid tied breaker.
Hint
, the CTs must read the current that the utility meter reads at the main's
utility entry point.
•
CT Orientation: the CTs label is marked, “House(K)-->Grid(L)”
•
CT Wiring: this has been the most troubling because installers use conduit
that is too small to pull through the inverter's four pin green CT connector. If
the wires must be removed, mark with tape (electrical or otherwise) the L1
(left side) and L2 (ride side) pair before removing the connectors. See diagram
below.
Hints,
Other conditions that hinder the Meter System Verification check.
•
L1 and L2 power imbalance. If L1 and L2 current is different by more than 8
AAC the system may not commission. Use current meter to identify and turn
off some of the home breakers (most likely single 120 V breakers) that are
causing the imbalance.
•
Rapid changing loads. If the home load or system power is not stable the
system may not commission. Items that cause rapidly changing loads are:
1.
Solar production in either the AC or DC coupled system. Try
commissioning with the solar off.
2.
Home furnaces, AC unites, electric hot water heaters, pool pumps, vacuum
cleaners, etc. Try turning off all home double (240 breakers).
3.
Battery charging above 90% (i.e. the inverter's 4th battery indictor is
blinking. See indicator below. Wait until battery charging is nearly
completed as shown by the green 10kWh battery SOC circle indicator.
The state of charge is indicated
by the amount of the ring that
is filled. The ring to the left
is indicating that the state of
charge is at 75%.
Prerequisites / Tips for Success
