Ontario Electrical Safety Code - Bulletins 50-1-0 Bulletin 50-1-0 Installation of Solar Photovoltaic Systems Section 50; Rules: 84-020, 84-024, 84-030; Tables 11 and 19 Issued July 2010 Scope (1) Introduction (2) Wiring methods within a photovoltaic array (a) Acceptable wiring methods within a photovoltaic array (b) PV wire or cable approved to UL standard UL 4703 (c) Combiner box (d) Cable support (e) Attachment plugs (3) Single-line diagram and labels (a) Single-line diagram of the interconnected renewable system (b) Labels (4) Voltage rating of photovoltaic circuit (5) Electricity meters (a) Neutral connection for electricity meters (b) Generator metering connection (c) Tapping to the load side of the service box for a parallel metering connection (6) AC modules and micro-inverters (a) Disconnecting means (b) Overcurrent protection (c) Marking of photovoltaic circuit 50 (1) Introduction With the introduction of the Green Energy Act and Feed in Tariff (FIT) program that was launched in Ontario, many renewable energy projects are under development. Electrical contractors and PV installers have asked questions and raised some issues that are addressed in this Bulletin. In addition to this Bulletin, the following documents provide additional information on the installation of solar photovoltaic systems: ESA SPEC-004 Electrical Guidelines for Inverter-Based Micro Generation Facilities ESA SPEC- 005 Process Guideline for the Installation of Parallel Generating Systems (10kW or Greater) Bulletin 50-2-* Grounding and Bonding of Solar Photovoltaic Systems Bulletin 84-1-* Interconnection of Electric Power Production Sources 2) Wiring methods within an array (a) Acceptable wiring methods within a photovoltaic array Acceptable wiring methods for use within a photovoltaic array are: Flexible cords for extra-hard usage as per Rule 50-014 requirements; Conductors approved for exposed installations where subject to the weather as listed in Table 19. Although not listed in Table 19, type RWU conductors shall also be permitted. PV wire or cable approved to UL standard UL 4703 Page 1 of 8
50-1-0 Ontario Electrical Safety Code - Bulletins (b) PV wire or cable approved to UL standards Direction 1 In Ontario, in addition to cables permitted by OESC, PV cables approved to UL Standard, UL 4703 Outline of Investigation for Photovoltaic Wire is an acceptable wiring method within a PV array. PV cables approved to UL Standard UL 4703 have the following characteristics: Voltage Rating: 600 V, 1000 V and 2000 V Temperature Rating: 90 C wet and 90, 105, 125 or 150 C dry Number of conductors: single, insulated, stranded copper conductor, size 18 4/0 AWG Sunlight resistant and marked as Sunlight Resistant or Sun Res. Marked as PV Wire, PV cable, Photovoltaic Wire or Photovoltaic Cable.. Rationale PV cables certified to UL Standard UL 4703 are designed for rooftops tough environments, often subject to snow, ice and scorching heat. Cables marked as PV Wire, PV cable, Photovoltaic Wire or Photovoltaic Cable have 30 C higher temperature rating compared with extra-hard usage outdoor flexible cords and with the option to even withstand 150 C. There is no equivalent Canadian standard for PV cables. The Photo B1 shows typical construction details for PV cable. Photo B1 - Typical construction details for PV cable (c) Combiner box Appendix B note to Rule 50-002 shows the diagram of a typical solar photovoltaic system and a device referenced as a combiner box. ESA SPEC 004 defines a combiner box as A box used in solar installations to combine the multiple photovoltaic arrays to produce one circuit. It often contains generator overcurrent devices. The combiner box is permitted to be installed on the roof and it is preferred to be as close as possible to the PV modules forming an array. The purpose of the combiner box is to group the wiring from the array into one cable run to the inverter, which reflects the logic to have the combiner box as close as possible to the array (on the roof), as per the Photo B2. Direction 2 Wiring methods specified above (subject (2)(a) of this Bulletin) are acceptable for interconnecting PV modules within array. Therefore, if the combiner box is located outside of a building or a structure and within 1 m from the physical edge of the PV modules, acceptable wiring methods within array shall be permitted to be extended. Page 2 of 8
Ontario Electrical Safety Code - Bulletins 50-1-0 to the combiner box Where a combiner box is not located within 1 m of PV modules or where conductors are run inside the building or a structure, wiring methods specified in Section 12 are required. Photo B2 Combiner box (d) Cable support Cables and conduit shall be properly supported and shall not lie loosely on the roofing material. Notwithstanding Rule 12-206 requirements for open wiring support, acceptable supporting means are considered to be straps or other devices located within 300 mm of every box or fitting and at intervals of not more than 1.5 m throughout the run. This requirement is similar to supporting requirements for non-metallic-sheathed cable as defined by Rule 12-510(1). Photo B3 is an example of unacceptable cable support. 50 Photo B3 Unacceptable cable support (e) Attachment plugs As per Rule 50-016, the plug-in connectors are required to be of the locking type and be rated for the voltage and current of the circuit in which they are installed. Photo B4 shows an example of a connector that meets Rule 50-016(d) requirement. Locking connectors required by Rule 50-016(d) do not need a tool to unlock. They shall incorporate a suitable latching mechanism between the mated pair. Attachment plugs may not be rated for interrupting the current and be marked with a warning indicating that disconnection under no load is necessary. In this case, the modules must be disabled before disconnecting the connectors. Page 3 of 8
50-1-0 Ontario Electrical Safety Code - Bulletins Photo B4 Example of a PV wire connector (3) Single-line diagram and labels (a) Single-line diagram of the interconnected renewable system Question 1 Does Diagram B1 meet the requirements of Rule 84-030(2) for the single-line diagram of the interconnected system that is located at the supply authority disconnect switch? Diagram B1 Typical single-line diagram of the interconnected system with parallel meter connection Answer 1 Yes, this meets the minimum single-line diagram requirements of Rule 84-030(2). Note: The system ratings required by Rule 50-004 are not required to be displayed at the supply authority disconnect or on the single-line diagram. The label required by Rule 50-004 shall be posted at the generator (Source) disconnecting means. (b) Labels Question 2 What Codes or Standards provide requirements for labels, e.g. DG SOURCE DISCONNECT, UTILITYINTERCONNECTED, DG SYSTEM DISCONNECT WARNING TWO POWER SOURCES? Does the code require specific wording? Answer 2 Rules 2-100 and 84-024 require the labels. However, the rules do not specify the specific wording. The wording provided in ESA SPEC-004 can be used as an example. Page 4 of 8
Ontario Electrical Safety Code - Bulletins 50-1-0 The following markings are applicable CSA Part 2 standards requirements and can be used as guidance: CSA Standard C22.2 No. 257 defines Distributed generation (DG) as an electric generation facilities connected to a distribution system through the point of common coupling. In Annex B of Standard C22.2 No. 257 that is informative shows similar labels as in ESA SPEC-004, i.e. DG - source disconnect means. CSA Standard C22.2 No. 107.1, Clause 15.4.1.1 requires When the unit complies with Clause 15, it shall be marked: UTILITY - INTERCONNECTED, or the equivalent, and Clause 15.4.1.3 specifies: A utilityinterconnected inverter shall be marked: WARNING - POWER FED FROM MORE THAN ONE SOURCE, or the equivalent. Question 3 What is considered acceptable for exterior, weatherproof labels required by Section 84? Does the code specify letters size? Answer 3 The Code does not provide specific requirements; the labels need to be able to withstand the elements, be permanent and legible, for example: lamacoid, engraved metal plate, or equivalent. Additionally, the label has to satisfy the local supply authority requirements. (4) Voltage rating of photovoltaic circuit Rule 50-006 requires the voltage rating of photovoltaic source circuits to be the rated open-circuit voltage of the photovoltaic power source multiplied by 125%. A PV source is not a constant-voltage source and increases with decreasing temperature. The 125% safety factor is based on a minimum module temperature of - 40 C. 50 Notwithstanding Rule 50-006 requirements, when open-circuit voltage temperature coefficients at - 40 C are different than 125% as supplied in the manufacturer s instructions for certified PV modules, ESA will consider the deviation to use the designed open-circuit voltage temperature coefficients at - 40 C instead of using the 125% factor. The deviation request should be issued to ESA in accordance with Bulletin 2-21-*. (5) Electricity meters (a) Neutral connection for electricity meters Question 4 For a parallel metering connection, where the generation meter is on the supply side of the service disconnecting means, do all 4-jaw revenue meters require a neutral conductor to be terminated in the meter base? Answer 4 No. According to Rule 10-624(2), the grounded conductor on the supply side of the service disconnecting means is permitted to be used as a bonding conductor for the revenue meter device. In this case the grounded conductor is required to be bonded to the meter mounting device. However, when the grounded conductor is not used as a bonding conductor for the revenue meter device, the grounded conductor can be run through the meter base without being terminated and a separate bonding conductor shall be provided between the service and the meter. Page 5 of 8
50-1-0 Ontario Electrical Safety Code - Bulletins (b) Generator metering connection Direction 3 The requirement in the ESA SPEC-004 is to always have the Line side of the metering cabinet connected to the utility and the Load side connected to the customer to ensure consistency and safety, as per Diagram B2. Diagram B2 Generation meter connection Rationale When pulling a meter, the standard practice is that the Load side of the metering cabinet will be de-energized and caution is taken around the Line side as it maybe energized. The ESA guideline is consistent with the Ontario Power Authority s (OPA s) microfit Contract which requires bi-directional metering for the generator facility. (c) Tapping to the load side of the service box for a parallel metering connection Question 5 In installations where the existing customer load meter is downstream of the main service disconnect, does the code permit tapping to the load side lugs of the service disconnect for a FIT or microfit installation with a parallel metering configuration, as per attached Diagram B3? Diagram B3 Tapping to the to the load side lugs of the service disconnect Page 6 of 8
Ontario Electrical Safety Code - Bulletins 50-1-0 Answer 5 Yes; According to Bulletin 6-7-*, maximum one tap is permitted per service box. Therefore, the generator meter in a parallel configuration is allowed to be connected to the load side lugs of service disconnect and be terminated in accordance with Bulletin 6-7-*. (6) AC modules and micro-inverters Rule 50-002 defines AC module as a complete, environmentally protected assembly of interconnected solar cells, inverter, and other components designed to generate ac power. AC modules are designed to generate AC power when exposed to sunlight and do not have accessible, field installed DC wiring (as shown in the Photo B5). (a) Disconnecting means For AC modules where the inverter is an integral part of the generator (as shown on Photo B5), and the combined unit is approved, there is no requirement for a disconnecting means as required by Rule 50-012(1). However, if any other electric power production source is interconnected with an AC module, the disconnecting means in accordance with Rule 84-020 is required for all production sources. Photo B5 AC module where the inverter is an integral part of the generator 50 For Micro-inverters, inverters plugged into the photovoltaic panels (as shown on Photo B6), no additional disconnect switch is required Photo B6 Micro-inverter (b) Overcurrent protection Page 7 of 8
50-1-0 Ontario Electrical Safety Code - Bulletins The output circuits of AC modules shall have overcurrent protection according to Rule 50-010 requirements (c) Marking of photovoltaic circuit Question 6 Does the OESC require marking of PV system with AC modules when interconnecting to the supply authority? Answer 6 Yes. Although requirements of Rule 50-004 for marking of photovoltaic output circuit at generator disconnecting means are not applicable to AC modules, according to Rule 2-100, PV installations utilizing AC modules connected to the supply authority shall be marked to identify PV system rating and suitability for the particular installation. Question 7 What is the required marking for PV system with AC modules? Answer 7 According to Rule 2-100 and the intent of Rule 50-004, the required marking for PV installations utilizing AC modules connected to the supply authority are: rated AC output current nominal operating AC voltage Question 8 Where is the marking for PV system with AC modules required to be located? Answer 8 The required marking for PV installations utilizing AC modules connected to the supply authority shall be located at the supply authority disconnect; or be included in the single-line diagram required by Rule 84-030(2). Page 8 of 8