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
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.
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.
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.
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.
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.