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BATTERY BACK-UP SYSTEM FOR REIREMENT VILLAGE - ADVICE PLEASE


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Power Forum – Retirement Village Queries 2023/05/10 – Keith Fawcett, Hout Bay

 

Current Status

1.       I live in a Retirement Village in Cape Town – 40-Units (30-off 2-Bedroom Cottages + 10-off Single Bedroom Flats.

 

-          I am seeking to make a ‘sensible/well-reasoned Submission’ to the Body Corporate to address the problem of Load Shedding.

-          therefore, I need to be able to answer multiple queries

 

2.       ALL Units are North-facing with Sloping Roofs – all Units have individual Electricity Meters.

 

3.       There are currently multiple Solar Panels on the Roofs of Garages in the Car Parking area,- these Solar panels connect directly to City of Cape Town (CoCT) who ‘credit’ the Body Corporate (BC) Monthly Electricity Account accordingly – the BC then calculates the applicable ‘Electricity Usage’ accordingly to each Unit.

 

4.       There is (currently) NO Battery Storage facility – except for one medium-size Back-Up Battery to power the Security System at the Complex (Electric Fence – Security cameras, Electric Entrance Gates, some Security Lights, Communication to security Company, etc.)

 

5.       The ‘harvesting’ of our Solar Energy is ‘lost’ during Load-Shedding periods – since there is NO Electricity Connection to CoCT during that period.

 

QUERY-1. – ONE LARGE SYSTEM COVERING ALL 40-UNITS

6.       Is it feasible to install “ONE LARGE” Battery Back-Up system sufficient to provide (being the equivalent of a single 5kwh Inverter Battery Back-up to each Unit)?

 

7.       Is there a system which would prevent the ‘tripping’ of such a System if a Resident turns-on a high-power usage Appliance e.g. Kettle, Electric Heater, etc., and shutting-down the entire electricity supply to the whole Complex?

 

QUERY-2. – INDIVIDUAL SYSTEM FOR EACH UNIT

8.       Is it more feasible/more economical, to install individual 5kwh Inverter/Battery Back-up installations to each Unit?

 

9.       Initially (Phase 1 of the Project) we would be looking at installing individual Inverter/Battery Back-up – without Solar Panels, i.e. each Unit would be ‘harvesting’ Back-up energy from the CoCT – we are aware that there is a current ’back-log’ of supply of Solar Panels of approx. 12-months, but we need an interim solution to the Load-Shedding.

 

10.   Subsequently (i.e. Phase 2 of the Project), we would advance to installing individual Solar Panels to each Unit to harvest energy into their existing Battery Back-up systems.

 

11.   There would /could possibly be facility for further ‘harvesting’ of this ‘now-extended Solar power’ for supply to CoCT – after the individual Battery-Back-ups were fully charged (?).

FURTHER CONSIDERATIONS

12.   We are living in a Retirement Village with elderly Residents.

13.   We would not wish to have a variety of different Inverter/Battery Back-up systems.

14.   We cannot expect our elderly Residents to be subjected to ‘poorly reasoned’ Inverter Battery Back-up systems.

15.   ‘We’ would require systems which are well-designed for our particular requirement(s), and well-serviced’ by a reputable Contractor.

I have taken the opportunity to ‘ask advice’ from the Solar Forum, in the hope that I can be able to supply well-reasoned/well -researched written advice.

 

Best Regards

Keith Fawcett

[email protected]

(Retired ‘Scientist’ – 80-yrs old in September 2023)

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  • 1 month later...

Hi Keith,

I am indirectly involved in a very similar retirement village setup in KZN (South Coast)

The developer supplied a basic load shedding backup unit for every unit , which worked OK, with some limitations.

Installations are between 1 and 5 years old.

The issues were many though:

1. Who insures the inverters and batteries?

2. Who is responsible when the units fail, and upgrade/replacement is required?

3. Most residents do not understand how the units operate.

The current situation is that residents are now installing their own much upgraded solar systems.

The developer still supplies basic systems, no solar

Maintenance on the basic systems is moving away from the body corporate/developer to a 3rd party (still in progress)

Adrian

 

 

 

 

 

 

 

 

 

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Hi,

Have done similar research and it gets a bit tricky.

 

The issue comes with:

  • Geysers - which will run for 45min
  • Stoves which could use 8KW for long periods of time.
  • Heaters which could run for a long period of time.

Smart switches - with Wifi - could drop the geyser and stove quite easily. Heaters (and similar) are more difficult. I would not run a geyser on battery backup.

There are huge economies of scale that you can get from a central system. If we exclude geysers, ovens and large electric heaters I doubt that many of the units will use more than 500W average - even in the evening. But when a kettle gets turned on that will raise to 2.5KW. Adding a microwave at the same time and you could easily get to 3.5KW - 4KW.  However, this happens rarely. Although people do eat at similar times - the times will never completely overlap. A single unit will likely escape with less than 2kw - about 90% of the time. In this way a combined system can benefit from the "diversification".

Batteries are the expensive part of any system. From my personal experience, I need a 5KWh battery to run a run 5KW load - which happens less than 1% of the time. But, my average load is less than 500W - implying not more than a 2kwh battery to survive 4h of load shedding. I have used 3kwh less than 1% of the time. If you can reduce the maximum demand (per unit) with a combined system - you will have huge savings. The cost of batteries is roughly R7k/kwh. Using my example - that is a R21k saving per unit.

The issue is that a few users could impact everyone negatively - and then it becomes a free for all. But if you can get people to "play ball" the cost is significantly less. Charging people more for power when there is load shedding - particularly at night - might help solve some of the issues but trying to explain that. :( 

A couple offsetting factors:

  • In older buildings, provisioning a Wifi network might be more difficult.
  • The individual installations costs are reduced - with all the addition DB wiring, space, batteries, etc.
  • The additional costs of the additional smart switches, Wifi, etc.

As a starting point it might be worthwhile to monitor the overall power demand and see how that compares to 5KW per unit. 

 

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On 2023/05/10 at 12:09 PM, Keith Fawcett said:

There is (currently) NO Battery Storage facility – except for one medium-size Back-Up Battery to power the Security System at the Complex

You could expand the existing security system for lights and one plug (<10A) at all units. Those who wish to install an inverter at their own living unit, why not.

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