I notice on Google Maps that many malls in Centurion have substantial solar arrays on their roofs. How is this power managed? To store it would require enormous battery installations.  Anyone with first hand knowledge?

Probably they store it. Just use it during the day.

They usually install grid tied system to lower there Eskom bill with no backup accept a generator.

18 hours ago, hannesvn said:

I notice on Google Maps that many malls in Centurion have substantial solar arrays on their roofs. How is this power managed? To store it would require enormous battery installations.  Anyone with first hand knowledge?

Grid tied without batteries just happens to be the most cost effective way to use PV. It is only because of LS that most don't even consider the grid tied option. Also it does not mean you want to have to feed back into the grid.

Most of these commercial companies including Makro use Grid tied systems. Makro have all of their car parks connected to Solar PV & they have Solar Edge PV inverters that are Grid tied. So there is no backup power available if the Grid goes down. Interesting enough the PV inverters are mostly IP65 & live always outside near to the Array & there is good reason for this. The PV DC wiring is a plenty. However, the AC cable is bi-directional & only one AC cable of the required thickness is required. Makes sense to save the costs of all the string DC cables to keep them as short as possible. Typically the PV array DC voltage is 1000v string limits. So long strings are possible. 

In our small world of Residential Solar PV projects we think of the 48V system as a way to power our homes. I can tell that the Original poster here is asking where do they store this power & also how is possible to store so much power into 48V batteries. 

The answer is not 48V... Commercial level power that is above 30kW 3phase energy requires the High Voltage battery DC power. Voltronics has a solution with 2 inverters namely a 20kW 3 phase & a 30kW 3 phase big trolley inverter. The smaller 20kW machine cannot be paralleled & scaled where as the 30kW machine can be paralleled up to 4 times to provide 120kW. The DC voltage range is 366V up to 550V on the battery bus. We install these for any power requirement that is larger than 30kW & needs to be grown in the future. Our battery of choice for this solution is the Pylontech H1 Cube. It has 74ah Pylontech 48V modules that connects in series to build.up the high voltage. This then pairs into a HV BMS controller then into the inverter with a card to pair the Comms with the inverter. The solution is magic!!!

This is lethal voltage but the fundamental pros of such system is less amperage for the given voltage. Power = Volts X Amps. The advantages of the HV Battery is that the cable size for these large power requirements are like 25mm cable because the amps at max discharge for the 30kW inverter is 17A DC. A similar sized 48V battery would require at least 70mm or above type of cable. 

Pylontech, FreedomWon, Solar MD & even Livoltek manufacturer these HV batteries for commercial use. The other day I actually saw a Sun grow residential inverter with this setup also at a supplier. The 48V battery looks to use too much copper. It's days will be numbered in the not so distant future. 

 

2 hours ago, Steve87 said:

Most of these commercial companies including Makro use Grid tied systems. Makro have all of their car parks connected to Solar PV & they have Solar Edge PV inverters that are Grid tied. So there is no backup power available if the Grid goes down.

With the load profile of a shopping mall or office block mostly on during the day it makes sense to have a grid tied solution with little or no backup. 
But are these guys still without power during loadshedding? 
Must be frustrating to have all those solar panels on not being able to use the power during loadshedding.
Surely there must be a way to disconnect from the grid and keep the power on while controlling the load (switching off AC etc)?

Edited July 21, 20223 yr by Pietpower

Safety feature of on Grid inverter is to switch off if no Eskom is available. 

1 hour ago, Pietpower said:

Must be frustrating to have all those solar panels on not being able to use the power during loadshedding.
Surely there must be a way to disconnect from the grid and keep the power on while controlling the load (switching off AC etc)?

Some of the more high tech designed systems installed will have microgrids which switch on when there is loadshedding which then allows the grid-tie solar to continue feeding in.

Here is also an example of how you can do it with home solar.

https://www.payperwatt.com/post/3-ways-to-use-grid-tied-solar-during-power-outage

Edited July 21, 20223 yr by WannabeSolarSparky

We also went grid tied at work two years ago - something like 1400 x 355Wp pannels. Saves our 24/7 factory around 20% off our Eskom bill.  The off grid arrangement was far the most cost-effective solution but with silly loadshedding levels we had no choice and are busy installing a 650kVA generator.  The daytime solar recovery is a useful fuel saver - we expect around 25% redcution from the quoted figures of around 100l/hr at 75% rating.  We also looked at batteries for loadshedding support and energy arbitrage but the paypack is not very interesting at this time.

It is well documented how to use a Fronius grid tied with Victron backup with storage. There is a control that goes to the Fronius to throttle back. Some members are working on a way to use the Solis 4g/5g with Victron.

My own take on this is much easier. Due to HV inputs to a Kodak/Axpert 450V MPPT would be to merely switch the PV from grid tied inverter to the HV Kodak and use the power from the Kodak. It need not be connected to a battery but the battery can serve the purpose of creating stability during cloud periods.

By having a generator this can be used as the grid reference as long as the genny is about 2 times the size of the grid tied output.

The above is just how I think it can be used. Thinking small scale. On bigger systems there will be other tech employed. No problem cannot be overcome.

Edited July 21, 20223 yr by Scorp007

3 hours ago, WannabeSolarSparky said:

Some of the more high tech designed systems installed will have microgrids which switch on when there is loadshedding which then allows the grid-tie solar to continue feeding in.

Do places like Makro etc use this micro grid systems?

Where can I see more of how it works?

6 hours ago, Pietpower said:

Do places like Makro etc use this micro grid systems?

Where can I see more of how it works?

Some wiring details in the link above/below on how the genny would be wired including changeover switch.

Edited July 21, 20223 yr by Scorp007