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COCT buy your electricity at the same unit prize that they buy it from Eskom. COCT needs to have a electrical network in place that can handle the load if the PV does not work for example if there a a month of very cloudy weather PV would be of no advantage to City of Cape Town.

The big qeustion here is, is this in Eskom area or COCT area. Does this block of flats have a bulk meter supply point or individual metering from Eskom or City of Cape Town. In the COCT there is differant rules for PV on a bulk meter point and induvidual meter points from City of Cape Town. If the block of flats have a bulk meter point COCT sees it as one solar installation. With does comes rules as well. When the exspoprt capasity is 30kVA or more and there is more than one inverter a central disconnecting device must be installed with a out of bounds relay. When the export is 100kVA and more SCADA must be installed so that it can comunicate with COCT.

Also note the operation of the change over switch is not clear. If you hand in this drawing the COCT may ask you to draw in the blades of the change over switch.

If you look at the drawing the change over switch switched from Eskom or COCT to the DB board then when you switches the change over switch it completely cuts off the grid and the DB board now get a supply from the inverter. This is the reason they call it an alternative supply. You will also notice that the inverter never gets a supply from the DB board A UPS get a permanet supply from the DB but the inverter must conform to the SANS code (cannot remember the number) for UPS systems

Hi There are more that one code that City of Cape Town use when it comes to inverters. They are sans 10142 and NRS 097. The list of inverters by City of Cape Town is list that has type test certification under the NRS 097. Any person/company can put there inverter on the list of City of Cape Town if they can prove that the inverter has type test certification under the NRS 097 Any grid tied inverter (grid-tied means inverter that is connected directly to the DB board iraspectable if you feedback or not) must be an inverter that has type test certification under the NRS 097 this means the inverter must be on the approved inverter list of City of Cape Town. The only inverter allowed that can be directly connected to the DB board without the inverter being on the approve inverter list of City of Cape Town is a UPS inverter. A inverter will only be accepted if the inverters conforms to the applicable SANS code for UPS systems. The other system is an alternative supply system - no need to use an approve inverter at all and the completely off-grid system which is not connetect to the internal wiring of your premises aklso no need for an approved inverter. The above is applicable all SSEG installation in the City of Cape Town area

Following is the limitations on domestic installations that is grid-tied. Please note grid-tied is when the inverter is connected to your internal wiring of your house iraspectable if you feed back onto the grid or not. 99% of house in COCT area has a 60Amp supply On a 60Amp supply the limitation to feedback into the grid may not exceed 25% of the main breaker size which is 15Amp, 3,5 kVA. This is how the above figures get determinated. If you do not feedback into the grid the limitation is 100% of your main breaker size for 60Amp single phase is 13,8kVA but a reverse flow blocking device must be installed etc The other limitation is that the current that your inverter draw from your DB board to charge yor batteries may also not exceed 25% of the main breaker size which is 15Amp, 3,5 kVA. For grid tied systems you must use an inverter that is on the aprove inverter list of Cape Town. All the inverters on the list is inverter that was proven to City of Cape Town that they have type test certification according to NRS 097. Any company can put there inverter on this list if they can provide a valid type test certification for that inverter.

The drawing provided is a standby alternative supply SSEG system and not off grid. Off grid systems is totally seperate from your house wiring. Why it is called alternative supply is because your DB board either get a supply from the PV system or from the grid. This system is legal in the City of Cape Town area. In the old day it was called off-grid but City of Cape Town changed it to stand-by due to the confution people have with off-grid systems