On the 25th November 2019 AREP hosted a webinar with the City of Cape Town in order to provide members with a platform where representatives from the city could respond to technical questions on the registration of solar systems in that region.
The webinar was recorded and available for those interested in the original audio. A written version of the discussions can be seen below. The audio track can be downloaded as well as a PDF version of the complete document.
- Q1: What is the design and installation requirements for off-grid as opposed to grid tied systems in the City of Cape Town region? (6min04s)A: The City of Cape Town’s website has two forms that deal with design and installation requirements for solar PV systems and these documents provide relevant detail about the completion and sign-off processes involved.The forms are;
– Declaration for off-grid systems
– Application for grid tied systems
- Q9: If from 01 Jan 2020, the 2017 edition is applicable and there is no extension, will a list of inverters that comply with the 2017 version be published? (21minutes 55 seconds)Q2: When is an installation grid connected and when is it deemed off grid? (8min 00sec)A: The requirements for the different types of systems are listed in the “Declaration for off-grid systems” as well as the “Application for grid tied systems” forms and explained in greater detail in the “Requirements for Small-Scale Embedded Generation” document.In the forms on the website 3 categories are listed, they are;
- Passive standby ups utilised off grid hybrid SSEG
- Normal SSEG alternative supply in terms of SANS 10142-1
- Grid tied; SSEG connected to the utility grid directly or through customers internal, wiring
- grid tied SSEG that is connected to the grid through a reverse flow blocking relay is also considered grid tied
- Electrically separated off grid installation that is not inter-locked with the utility grid as a switched alternative – typically for a free standing swimming pool or pump
For reasons of clarification: Off-grid systems; also referred to as an Off-grid SSEG system is physically separated, electrically isolated and can never be connected to the utility electricity grid, either directly or through a customer’s internal wiring. Customer loads cannot be simultaneously connected to both the grid and the SSEG generator. A SSEG that is connected to the grid through a reverse power-blocking relay is not considered to be off grid.
- Q3: Is the same process for registration followed throughout the Western Cape and do the various municipalities have a consistent approach throughout the City of Cape Town within the city’s 3 areas; (10min 20seconds)The same approach is followed throughout the different regions of the City of Cape Town in terms of the SSEG process.
- Northern Suburbs, Bloemhof Head Office covers the area of the northern suburbs; Bellville, Parow, up to Helderberg and Somerset West
- Southern Suburbs, Wynberg Head Office covers the southern suburbs; Wynberg, Muizenberg, Llandudno, Mitchells Plain, Cape Flats
- City area which moved to Electricity House in Hout Street Cape Town is responsible for the CBD and outlying industrial areas – Epping, Athlone and Residential Vanguard Estate
- Q4: Drakenstein Municipal District – Do they follow the City of Cape Town’s regulations or do they have separate requirements? (12min 0 seconds)A: City of Cape Town cannot respond on behalf of the Drakenstein district, however;The AMEU compiled documents, which included the application forms and requirement documents, which were distributed to all other municipalities. They are probably using these documents.
- Q5: Meters and metering; Do meters get replaced once the process is approved and who pays for the replacement of the meters? (13min 10seconds)A: The City of Cape Town has an extensive programme with regards to metering called the MRP (Meter Registration Programme). Whether or not the city pays for the cost of replacing the meter is determined by whether the customer is interested in exporting power or producing power for own consumption.In Residential installations where the customer wants to produce for own consumption, and where there is an old revolving credit meter, the City will replace the meter with a prepayment meter at the City’s cost. Customers wanting to install a grid tied system that exports to the grid must pay for an AMI meter, however meters will be replaced at The City’s cost for customers that do not want to export.With Commercial Customers; 14minutes 46 secondsDependent on whether they want to export as well as the size of the system. Large power user will already have an AMI meter so meter does not need to change.Should the meter be a (SPU) small power user i.e.60 amps 3 phase or 80 amp 3 phase, the metering will be pre paid meter (PPM) and will also be free of charge.
- Q6: NRS certification – how to get inverters registered for NRS and how to get the inverter added to the approved list. (15min 35seconds)It is understood that, inverter manufacturers need to go through the NRS Certification process with an independent Bureau Veritas type of institution. The NRS Certification and Report should then be submitted to the City of Cape Town for approval and inclusion to the approved list of inverters.A: New or additional inverters must be in accordance with current NRS 097-2-1 2017 version.According to NRS 097-2-1 2017 Clause 184.108.40.206 has been relaxed and the frequency band has been changed from 30khz to 148kHz where previously it was 3khz to 148kHz, it remains at 3, but has been relaxed to 30. Documents that should be submitted to the City of Cape Town are the Certificates and summary test report where sensitive testing information can be omitted if desired.
- Q7: Industry question – Frequency requirements in the NRS 097-2-1 2017 document what happens if inverter manufacturers don’t comply? (17min 00 seconds)A: Frequency is still applicable. Frequency has just been relaxed from 3 to 30 kHz.The frequency between 3 and 30 kHz is not used in the power line communication spectrum, but from 30 upwards it is still a requirement.The Cenelec A-band frequency is from 3 to 95 kHz and the smart prepaid meter ELT split meter spectrum lies in the middle of that, so emissions are still applicable to system builds so that there are no disturbances on the network.
- Q8: NRS 2010 edition & 2017 edition (18min 00seconds)
Several manufacturers have certifications for 2010 and not 2017. As it is a huge cost to go through the certification again; do manufacturers still need to recertify inverters as per the 2017 version even when there are no changes in the various inverter models of the manufacturers?A: 2010 version did not include the requirement of the EMC standard.The PLC spectrum has become a requirement for smart metering and smart systems so therefore the frequency spectrum was incorporated into the 2017 version.The 2017 version is up for review, but, refers to EN or SANS50065-1, which provides limits that need to be complied with. The IEC spec 610001-2-2 brings out the similar parameters more or less.The NRS working group must decide what to have incorporated in the document to ensure that there is no unintentional emission coming from the inverters that will influence smart systems, that is just on the EMC standard where a difference exists between standards in the 2010 and 2017 version.Other issues refer to the central disconnect switch above 30 KVA, which is also brought into the requirements for the grid code for if more 100kVa for signals and controls.The 2017 version is the published document and remains applicable until amended.The fact remains that any inverters that have NRS 2010 edition certification must be re-certified.Inverters need to be recertified for them to be compliant beyond 1 Jan 2020.The City of Cape Town is engaging with industry and a decision to extend the certification period is under consideration. Currently the 2010 version is only valid until end December 2019. Many manufacturers have not complied with the 2017 version and a number of inverter models under 2010 have been discontinued.Industry must come forward to meet requirements of the emissions standard, through either the IEC or the EN spec.
- Q9: UPS and so called Axpert inverters, the one from Voltronix with various brand names on it, such as, Mercer and Synapse and so on – why are the Axpert inverters not on the list? Does this mean that it is illegal to use them? (22minutes 30 seconds)A: The Axpert inverter is considered as a passive standby UPS utilised as an off-grid hybrid system and that means that you use your grid assist that is another industry terms where you use the network for charging batteries and then the inverter or ups is in rectify or charge mode and it does no invert and when batteries are fully charged it changes state from charging to inverter mode and opens a switch by isolating the grid.The Axpert inverter is considered for off grid systems, as a passive ups or alternative supply.The switch in terms of wiring regulations must conform to SANS 60947-6-1 for a transfer switch, which is part of the sign off by an electrician in terms of electrical installation; there is no professional engineer or technologists, or technician sign off requirement for this.Signoff is required by a registered Department of DOL electrician registered as per the SANS wiring code. A test report must be attached to report and referenced. The test report do refer to transfer switches and also the SANS wiring code that is the same required test report and must be attached to the COC.Refer to requirements document (Appendix 4) on the City of Cape Town’s website for a document on the change over switch. Main requirement is SANS 60947-6-1.
- Q10: PowerPoint on 20 August 2018 regarding 30 KVA and above – is this document still applicable? (25minutes 20 seconds)SSEG power plants larger than 30kVA have additional municipal requirements.A: The question made reference to a presentation created and presented on behalf of the City of Cape Town for any solar PV system larger than 30kVA that required the central disconnect device, (CDD). For example, if have a 20kW Inverter and an additional 40kW inverter coupled in parallel, which gives you 60kW then you need 1 central disconnect switch.This can be compared to a single 60kW inverter with the central disconnect switch incorporated. The external CDD is then only required when more than 2 inverters coupled onto the same installation add up to more than 30kW.The CDD could be incorporated or be an integral part of the inverter itself, and only 1 inverter requires this device, then you do not need another CDD.
- Q11: Central Disconnect Devices (CDD)-do they need to be certified? Only certified devices can be connected. (27minutes 36 seconds)A: Yes correct that is a frequency and voltage relay – whenever a CDD switch is required it needs to be a type tested relay for that purpose, relay for only frequency and voltage for out of bounds conditions and that give the functionality to trip series contactors.
- Q12: Question posed by Randolf – which PLC is currently approved for DNP3 communication to their servers or plants for between 100kVA and 999kVA? What SCADA or PLC equipment is approved? (30minutes 00 seconds)A: DNP3 Grid code requirements; the City takes the DNP3 Ethernet communication medium from your system which is then reverted back to the City’s control room, but is only applicable to PV systems above 100kVa and up to 999kVa.A router that is VPN compliant is required at the customer’s premises where The City will pick up the communication from the router and convey it from the customer’s router to The City’s control room. For the Absolute Power Production Constraint and Power Gradient Constraint, it needs to be set up from the modbus or communication and converted to DNP3.
- Q13: Capacity of inverters or systems linked to the grid where you have single phase of 60 & 80 amp and 3 phase system where second rate 3.5 & 4.6kva connection. Is it allowed to install a larger PV system and limit the export capability of the inverter through hardware or via internal software in the inverter as stipulated in notes in regulations? (32minutes 00 seconds)A: That is correct. Hybrid inverters can limit the export capacity and in some cases; products such as ‘SolarLog’ or ‘Meteo-Control’ can limit the export.It is Important to note, yes, in terms of a 3.5.6 tmc single phase system allows the installation of a 6kva system as it will be close to the size provided by a supplier, but, the application will still be for a 3.5kva system Customers are allowed to throttle production through using Hardware or software by means of tool 3.5. It is important to note that a bigger inverter can be installed, however, the application must still be within its limits as per requirements document and yes, it limiting is allowed by either hardware or software.
- Q14: Installer and EPC complete application forms they must stipulate the size 3.4, 3.5 or 3.6kVA (34minutes 00 seconds)A: The application form requires that installers indicate the size of system being applied for. For e.g., If a 60A single-phase residential property application indicated a 8kVA system was going to be installed, it will not be approved even if it can be throttled. If however in the form it was specified as 3.5kVA then the municipality will see the inverter specs provided and that it actually is a 8kVA inverter for example. In terms of panels installed you are not going to install the number of panels for 8kva if you are limited to 3.5kva and the municipality in question will be able to note this on the application.