Frequently asked questions

Financial and revenue impact

It is recommended that residential tariffs which only include a c/kWh component be changed when an SSEG is installed to include both a fixed component (R/month) as well as an energy component (c/kWh) to protect municipal revenue.  It is important that the fixed charge is reasonable for the SSEG customer however, because otherwise it will destroy the customer’s SSEG investment return and thus encourage illegal installations which have not gone through the municipal approval process.

 

Modelling exercises undertaken in South African municipalities shows that it is possible to establish a suitable residential SSEG tariff which both protects municipal revenue and preserves a reasonable business case for customers. With commercial and industrial SSEG customers, there is often no need to adjust tariffs to protect revenue, because it is protected by the significant fixed charge component of such customer tariffs (for an example of a detailed revenue impact analysis and exploration of potential SSEG tariffs, see Tshwane SSEG Revenue Impact Report available at

http://www.cityenergy.org.za/uploads/resource_431.pdf ).

Or

Additional Content: Revenue / Financial Impact Tool & Guideline


Yes, SSEG systems will affect municipal revenue, but it is easily compensated for:

·       the revenue impact is usually not significant except for at very high SSEG penetration rates (which are unlikely in the medium-term)

·       it is often negligible in the commercial and industrial customer categories (who have tariffs with fixed charges which protect revenue when kWh sales drop)

·       in the residential sector revenue impact can easily be neutralised with appropriate residential SSEG tariffs

 

In general, electricity revenue from residential customers is affected by large numbers of SSEG installations (e.g. above 5% of customers) in situations where the residential tariff is only an energy (c/kWh) charge without a fixed monthly charge.  However revenue impact modelling undertaken for municipalities around South Africa have shown that there is seldom a serious revenue loss from foreseeable SSEG installation numbers, and an appropriate SSEG tariff easily compensates for such a loss. For Commercial and Industrial electricity customers with SSEG, revenue losses are generally not significant, if occurring at all, because the municipal revenue is protected by the significant fixed charge component of such customer tariffs.

 

For a municipality to clarify the potential revenue impact and appropriate SSEG tariffs for the residential sector in particular, it is recommended that modelling is undertaken, informed by a cost-of-supply study (e.g. using the GIZ SALGA SSEG Revenue Impact Model spreadsheet available at

Additional Content: http://www.cityenergy.org.za/category.php?id=5#14 )

Or

Additional Content: Revenue / Financial Impact Tool & Guideline


General

A solar PV system is made up of different components. For an Embedded Generation Installation (EGI) system, these include:

·       PV modules (made out of a groups of PV cells), which are also called PV panels or solar panels;

·       Grid tied inverter(s)

·       Wiring, and

·       Mounting hardware and/or a framework for the equipment.





                                    Figure 1: Basic EG Grid tied system example



For EGI with storage, additional components could include

·       one or more storage devices, like batteries;

·       a charge regulator or controller

·       and a battery inverter when alternating current (AC) rather than direct current (DC) is required;




                                                                        Figure 2: EGI with batteries Example


Additional Content: Introduction to PV solar_v12

·       The installed meter could stop to operate or get damaged

·       Electricity measurements could be incorrect and reconciliation between meters will be a challenge

·       The power quality of the network can be influenced negatively (for systems not adhering to the NRS 097-2-1)

·       For EG not adhering to the NRS 097-2-1 and/or without anti-islanding: could energise the network during utility maintenance.

The benefits

·       Excess electricity can be resold with a profit.

·       In some instances it can improve the power quality and/or the operation of the network

·       By replacing the meter it gives the utility the opportunity to upgrade their metering system

·       Electricity fed in the grid is carbon clean.

·       The customer does not need to install additional equipment to limit or cap the electricity being produced, which will

o   Help save on the capex cost for the consumer,

o   Maximise utilisation of solar production,

o   Prevent wastage of energy

o   And also prevent a scenario where the load and generation matches which could increase the chance of Islanding and energising the grid by mistake.


Here is a basic overview on how grid connected solar power systems work;

1.     During the day when the sun is shining, sunlight falling onto your solar panels/modules is converted into DC electricity (the semi-conductor material in the PV module performs this conversion).

2.     This DC electricity is conducted to a solar inverter which converts this DC electricity into AC electricity.

3.     The solar inverter then feeds this AC electricity into your house’s switchboard.

4.     This AC electricity is then used to power your house.

5.     Any power being produced that is surplus to your house requirements/load will be fed back to the local grid (reverse feed-in).

6.     If there is a power outage from the utility, the EG will switch off and stop operating until the grid is switched back on (this is also a safety requirement discussed under Fout! Verwijzingsbron niet gevonden..)



Figure 3: Diagram showing how a Grid Tied EG works (City of Cape Town Guideline for safe

                                           

  

NOTE: Compensation for reverse feed-in are only available in some municipalities: as of July 2018, 18 municipalities had NERSA-approved SSEG compensation tariffs. The tariff for reverse feed-in is also different between municipalities.


Metering

All of these metering or billing methods apply when an EG was installed.

·       Net-metering – Both the import (usage in kWh) and export (excess in kWh) of electricity is measured and the net effect (difference between the two) is indicated/displayed. The value of the exported kWh vs the imported kWh is 1:1. For example if 250kWh was used and 30 kWh exported, the net-metering will show 220kWh used and the customer will pay for the 220kWh used.

·       Net-billing – The same as net metering, but the only difference is that the value of kWh being exported is less that the value of the kWh imported. For example if 250kWh was used (for R1.50/kWh) and 30kWh was exported at R1.00/kWh, the customer will pay for R375 (250 x R1.50) minus R30 (30 x R1.00) which equates to R345.

·       Wheeling-billing – The billing of the transportation of electricity, over a utility’s electrical network from an EG in one place to a third party/customer in other place. For example a generator generates electricity for R0.80/kWh, the utility charges a R0.20 wheeling charge for using their network and the generator sells it for R1.00 or more to another customer.

Additional Content: Metering & Monitoring Requirements_v8


A four quadrant meter or bi-directional that measure both import and export of kWh.

One example for single-phase installations is the Elster AS230. An example of a three-phase meter is the Echelon MTR 3000.

Additional Content: Metering and Billing done in NMBM_Nov2017

 

Can prepaid meters be used for EG systems?

Yes, it is possible to program pre-paid meters to measure both import (supplied by the utility) and export (excess power being fed into the grid) and allocate a tariff for each. Unfortunately the tamper alert function for swapping the input and output will be lost in the process.


Municipal processes and regulations

The SSEG application process involves the customer filling out standard forms, from the AMEU-SALGA resource pack, which provide the municipality with the necessary system information to assess the proposal and either grant approval or not (or request changes or additional studies before approval). The municipality assesses the proposed system for safety, power quality, general grid impact and other issues before giving the customer the go-ahead or not.

Any customer intending to install a solar PV system which will be connected to the municipal distribution grid (including via their own house/building wiring) is required to go through the application process. Basic system design and other information is required in the process, and therefore residential customers particularly will generally need the support of a solar PV installer to fill out the necessary application forms.

 

Off-grid solar PV systems need not go through this application process (although approval from other departments such as Building Control/Planning may be needed in certain circumstances).


Additional Content: AMEU-SALGA Resource Pack_30Jan2017


It is completely optional whether municipalities want to be present, and even conduct tests such as anti-islanding, at system commissioning. Municipalities need to ensure that suitably qualified and registered personnel sign-off systems at commissioning, and as long as this requirement is made mandatory (for example by specifying it in the municipal ‘Requirements for Embedded Generation’ document) it is not necessary for them to be present at commissioning.  However some municipalities choose to be present, particularly when larger SSEG systems are being commissioned, partly so they can learn about the commissioning process and be exposed to different types of SSEG systems.  Given the rate at which the numbers of SSEG installations are accelerating, it is very unlikely that municipalities will have the staff to attend all, or even most, SSEG commissioning processes.


Additional Content: Commissioning process and sign off_v10

Additional Content: SSEG Commissioning Report with Tests_v1.1

 


·       If the Municipality is NOT informed about an installed EG

·       If the system is not registered when there were processes in place.

·       Tampering with the meter installation

·       The EGI does not comply with relevant existing regulations/standards

·       Alter the existing legal installation

·       A system that is not registered in terms of the Licensing Exemption and Registration Notice, published 2017/11/10.

·       No license for system >1MW

·       No connection agreement for <1MW

·       There is no CoC for the installation


Additional Content: Licencing Exemption and registration Notice_ 10Nov2017

 


 

·       Informing the general public (how it should be, safety, make existing laws clear)

·       Formalizing processes/by-laws must be in place.

·       Communication channels should be open and available.

·       In a supportive and feasible way get illegal installation to become legal; give amnesty period to abide by the rules.

·       Request to switch off their EG and only switch on after approval was provided by the Municipality once the customer went through the application process.

·       Pay a potential fine; for those not complying with corrective measures.

·       Disconnect supply after amnesty period, customer needs to re-apply for connection.

·       If the installation is unsafe in any way, disconnect supply immediately.

·       Inform the public about the PV GreenCard initiative, which has its own quality assurance processes; including realising EG legally.

 


Quality assurance

What is the PV GreenCard? Asked 2018 05 23

Some universities like NMU, Stellenbosch (CRSES) and UCT (ERC), have NQF Level 6-9 short courses in the field of renewable energy and sustainable development.

SARETEC has however recently obtained a SAQA ID number for a formal qualification as “Solar PV service Technician” at the end of 2016. In addition, with assistance from DGS and CPUT they developed short courses on the following;

1.     PV service technician (PV farms)

2.     PV service technical (Stand-alone/Off grid installation)

3.     PV installer (liaises with clients, conducts a site visit, obtains and analyses data, designs or customises or compiles a PV system, selects the appropriate components, installs, commissions and tests a PV system for functionality.)

4.     PV Mounter – (mounts pre-designed PV systems according to instructions from either a PV Installer/Designer.)


Additional Content: PV GreenCard Launch_2017

Additional Content: Career Path Training Modules_2016


Yes, SSEG systems will affect the power quality of the network. PQ limits have been specified in NRS 097-2-1 in line with international requirements in order to minimise this potential impact.

The level of PQ pollution contributed by an inverter depends on many factors, but it is anticipated that the impact would be benign in the majority of cases. Experience and measurements in Belgian residential networks have shown a beneficial impact of inverters, since they mostly cancel distortion caused by other customer loads, e.g. Compact Fluorescent Lamps (CFLs).

 

What could the imbalance caused by SSEG, do to power quality?

Voltage unbalance mostly affects three-phase loads. The efficiency of motors is reduced and at high voltage unbalance, motors may overheat. Harmonic current emissions from rectifier loads, such as motor drives, may increase.

Voltage unbalance may lead to over- or under-voltage on one of the phases, which could affect customers connected to that phase negatively.

 

What are the power quality requirements for embedded generators?

Power quality emission limits for SSEG are provide in NRS 097-2-1 for current harmonics, voltage flicker and voltage unbalance.


Safety and standards

EG can influence the power quality and the safety of the network if improper equipment is used or if the generator-system is not properly installed. If the installation is not done according to certain rules/standards, it could result in potential risks for and can have a negative impact on the community. An example could be that the EG causes the voltage to rise too high, resulting in damage to the customer and neighbours’ appliances

Additional Content: Standards and Specifications_v11


Key specifications are the NRS 097-series, which defines the basic requirements at the interface. This series also references safety requirements, e.g. those contained in the IEC 62109-series.

Installations are regulated by the wiring code, i.e. SANS 10142-1. The SANS 10142-1-X is under development for SSEG installation requirements.

 

Additional Content: Standards and Specifications_v11

Additional Content: Standards and guidelines for the PV GreenCard_ Jun2016

 

In terms of SSEG, where does the NRCS fit in?

The role of the NRCS is to develop and administrate technical regulations and compulsory specifications. When this document was compiled, there was still uncertainty if NRCS will play active role when it comes to the components used for SSEG.

 

Should someone want to connect on the MV-side, which requirements/ standards are applicable?

Wiring regulations are provided for MV installations up to 22 kV and up to 3 MVA in SANS 10142-2. The LV side of the installation remains the domain of SANS 10142-1. Installations larger than 3 MVA or connected to voltages above 22 kV require the services of a professional engineer and most probably a Grid Impact study.

 

Where to find SANS documents?

SANS documents are available from the South African Bureau of Standards (SABS). It is recommended that municipalities evaluate group subscriptions to selections of SANS documents, to ensure adequate and cost-effective access to these documents.


Can't find what you are looking for? Send us your question: