6
REC Installation Manual - REC Alpha 72 Series - IEC 61215 /61730
Rev A - 02.20
Ref: NE-06-23
ELECTRICAL INSTALLATION
ELECTRICAL REQUIREMENTS
Application Class
REC solar panels are rated for use in electrical Application Class A, Protection Safety Class II; at hazardous levels of voltage (>35V), current(>8A)
and power (>240W) where general contact access is anticipated (panels qualified for safety through IEC 61730-1 and -2).
System Requirements
REC solar panels are only for use where they meet the specific technical requirements of the complete system. Ensure other components will not
cause mechanical or electrical damage to the panels. Only panels of the same type and power class should be connected.
String configuration
When connecting panels in a string, plan and execute according to the inverter manufacturer’s instructions. The number of panels connected to an inverter
must not exceed the voltage limits and operating range permitted by the manufacturer, nor under any circumstance exceed the maximum system voltage
as stated in the technical specifications for the product at the rear of this manual. The maximum system fuse rating (overcurrent protection rating) and
the maximum reverse current for each panel can be found in the technical specifications for the product at the rear of this manual.
The maximum number of panels in a string can be calculated by dividing the maximum system voltage of the panel by its V
OC
accounting for the lowest
ambient temperature at site, e.g.: for a 1000V system, if the lowest ambient temperature is 20°C, the panel has a V
OC
of 52.7 V and a temperature
coefficient of V
OC
of -0.24%/°C, the maximum panels per string is 21 (∆T°C = 25° - 20° = 5°; 5° x 0.3 = 1.5%; 52.7 + 1.5% = 53.5; 1000 V / 53.5 = 18.7, so a
total of 18 panels or 995 V). Qualified system designers can make exact calculations that account for specific project requirements and site conditions.
String connection
Panels connected in series must have the same ampere rating. The maximum number of panels that can be connected in series or parallel depends upon
system design, inverter type and environmental conditions. String configuration must correspond to the specifications of other system components e.g.,
inverter. Refer to the reverse current rating of the panel indicated in the technical characteristics at the rear of this manual or on the panel datasheet.
Wiring layout
To minimize voltage surges (e.g., indirect lightning strikes), cables of the same string must be bundled together so loops are as small as possible.
String configurations must be checked before commissioning. If open circuit voltage (V
oc
) and short circuit current (I
sc
) deviate from specification,
this may indicate a configuration fault. Correct DC polarity must be observed at all times.
Electrical Ratings
Electrical ratings are within a specific tolerance of measured values at Standard Test Conditions (STC) as given in the technical characteristics for each
panel at the rear of this manual. Allow for increased panel output as a result of conditions different to STC by multiplying the I
SC
and V
OC
values by a
factor of 1.25 (or according to local regulations) when determining component voltage ratings, conductor ampacities, overcurrent device ratings and
size of controls connected to the PV output.
MECHANICAL INSTALLATION
FIRE GUIDELINES
REC solar panels have a Class C fire classification. Utilize the following fire safety guidelines when installing REC solar panels:
• Check with all relevant local authorities for fire safety requirements for any building or structure on to which the panels will be installed,
• The system design must ensure that it can be easily accessed in the event of a building fire,
• Check with relevant authorities for applicable regulations concerning setbacks or other placement restrictions that may apply for roof-
mounted arrays,
• The use of DC ground fault interrupters is recommended. This may also be required by local and national codes,
• All electrical appliances are a fire risk. The panel must be mounted over a fire retardant roof covering rated for the application and a distance
of at least
60
mm between the panel and the mounting surface, to allow the free circulation of air beneath the panels at all times.
ORIENTATION
The optimal mounting position of a panel results in the sun’s rays falling perpendicular (i.e., at 90°) to the surface. To maximize system output, panels
should be installed at the optimum orientation and tilt angle. The specifics of this depend on location and can be calculated by a qualified system
designer. All panels in a string should, wherever possible, have the same orientation and tilt to ensure the system does not underperform due to
mismatched outputs. Dependent on local conditions, a lower angle of installation will potentially increase the requirement for regular cleaning.
DANGER -
Electrical shock
Safety is paramount when working on the electrical installation. Always follow the electrical requirements to avoid the risk of sparking, fire hazards,
burns and lethal electric shocks
.
