H2O Manual | 11
H2O for both safety and convenience. This
can be done either with a suitably rated
double-pole DC circuit breaker or isolator,
with a rating of at least 250V and 15A DC.
Note that if a DC breaker is used in this
location, it is not possible for it to trip on
over-current events, since the PV string
cannot generate enough current beyond its
operational curve to do so.
The Synapse H2O should only be connected
to a single, series connected string with a
Short Circuit Current (Isc) of not more than
10A. Multiple parallel strings of panels are
not allowed.
Before connection, check the polarity of the
incoming PV supply with a suitable DC test
instrument to ensure that the Synapse H2O
is not exposed to reverse polarity. Then,
with the PV Array exposed to full sunlight,
check that the PV voltage is within the
allowable limits of 60 –
220
V DC. Ensure
that the DC cables are correctly terminated
into original Staubli MC4 connectors only.
Figure 5. H2O DC input
Now connect the DC PV power supply to the
MC4 connectors on the H2O. (See Fig. 5)
Ensure that the H2O is protected with Surge
Protection Devices (SPD’s) on both the AC and
DC supply interfaces
.
Temperature sensor
The H2O is supplied with a temperature sensor.
It is designed to fit inside the thermal pocket of
the geyser, next to (with) the existing thermostat.
It is recommended that the thermostat is
removed, and the temperature sensor is
pushed a short way down the pocket – about
40mm. Gently reinsert the thermostat with the
temperature probe still in place. Be careful not
to damage the probe or its insulation as you
push the thermostat into place. It is important
that the temperature probe is secured in place
so that it cannot be accidentally removed, thus
causing an incorrect temperature reading.
Figure 6. Temperature sensor installation
Now connect the other end of the probe’s
cable to the H2O’s PCB as shown in Figure 7.
There are 2 connectors – connect each to their
respective locations, shown in the red blocks.
Note:
If the H2O's temperature probe is incompatible
with your particular thermostat / pocket
arrangement, it is necessary to add an
additional pocket to your geyser. These are
available as retrofit devices which can be
screwed into one of the unused ports.
