City of Sydney’s big solar plans: 1.25MW on 30 rooftops

The City of Sydney looks like it will claim the crown for the country’s largest rooftop PV installation with a 1.25 megawatt (MW) installation, edging out current record-holder University of Queensland’s 1.2MW system by just 50 kilowatts (kW). Although questionable whether the arrays constitute a single monolithic ‘system’, the tender for the project encompasses greater nominal peak capacity than any other rooftop project in Australia.

The systems, whose installation will take place over the next 2 years, will be spread across 30 properties in the City of Sydney, such as Town Hall House, Glebe, Redfern and Paddington town halls, the Redfern Oval grandstand, Railway Square bus station, plus a number of libraries, council depots, community centres within the CoS jurisdiction. The system will supply roughly 12.5% of the electrical power needs of City council properties, funded using the $2million/year budget previously allocated to purchasing GreenPower, and will complement the existing solar PV on rooftops of 18 other City properties. The solar plans fall into the greater framework of the City of Sydney’s plans for 2030, which include producing enough power to meet local electricity needs by 2030, and reducing its greenhouse gas emissions by 50% by 2030 and 70% by 2050.

Sydney’s solar project is an indication of the growing viability of commercial-scale solar power in this Solar Feed-in Tariff-free environment. In the absence of FiTs or affordable and efficient energy storage technology, solar’s strong suit is powering buildings that are occupied and consuming electricity during the day. In combination with an effective regimen of energy saving, efficiency, and awareness amongst those who occupy the buildings daily, solar PV is an excellent tool for both saving money and reducing CO2 emissions.

Although the main purpose of the 1.25MW of forthcoming solar PV installations is to trumpet the council’s green ambitions, underlying this seems to be the business case for investing in solar PV vs GreenPower, according to insights by Nigel Morris of Solar Business Services. Although in the short-term the price of producing solar power will be more expensive, the rising price of grid power means that producing solar power will likely more cost-effective in the long-term, especially in light of the City’s localised power generation goals.

“The City of Sydney is delivering on its commitment to reduce carbon pollution by 70 per cent and produce 30 per cent of its electricity from renewable sources by 2030 – one of the most ambitious programs of any Australian government,” Lord Mayor Clover Moore said in a media statement.

“The solar PV project produces no pollution when generating electricity – unlike coal-fired power, which is responsible for 80 per cent of our pollution.”

“Energy produced locally through solar panels, trigeneration systems or fuel cells will reduce the need to spend billions of dollars on new coal-fired power stations and network upgrades, which are driving up household electricity bills,” the Lord Mayor said.

Further proof of its desire to stand out as a leader amongst Australia’s local councils in the field of greenhouse gas emissions abatement, Sydney has even chosen to forego the effective federal government subsidy that is usually afforded to renewable power generation systems through the Renewable Energy Target. The City chose to ‘retire’ the Renewable Energy Certificates (RECs) rather than sell them. This was done “so that the City’s efforts to reduce greenhouse gas emissions through renewable energy projects will go beyond the Federal Government’s Renewable Energy Target–increasing the amount of renewable energy generated in Australia”, according to a tender committee document.

The price tag for the project is $6million, meaning that the overall cost per watt comes out $4.80, compared to a cost of between $2 and $3 watt for more competitive large-scale installations. In addition to the forfeited REC benefit, the cost difference can be further accounted for by considering the other factors involved. These include the broad, holistic, and community-focused nature of the City’s solar plans (and associated costs), the varied nature of the installations themselves (most are standard installs, but BIPV and solar electric vehicle charging points also appear in the list), as well as the top-end expertise and components that are to be employed.

This article was also posted on Cleantechnia.

© 2012 Solar Choice Pty Ltd

James Martin II


  1. Hello, I am the son of Thomas Swales who was the Consumers’ Engineer for St George County Council, situated in Montgomery Street Kogarah between 1947 and 1952.
    During those years Thomas, encouraged the factories in the St. George area to use Petrol and Diesel engines coupled to large induction motors, to augment the supply of electrical energy to The St, George area.
    The method of connection was known as “INDUCTION GENERATION”.
    The system worked well, and the factories liked being able to generate credits on their electricity bills.
    The blackouts that occurred were accordingly reduced in number and severity.
    The habit developed to use the Induction generators after daylight and high demand times to generate the credit with St George.

    I remember coming home from a Fellowship tea at St George Church of England Church, one night towards the end of 1950, and around midnight all the lights went out. Dad remarked that it was unusual to have a blackout at this time of night.
    The System Control people from St. George telephoned dad to tell him that the whole system had shut down, including the Railways generators that supplied St. George.
    When I studied Electrical Engineering, after my father died, I discovered that the limit of INDUCTION GENERATION (ungoverned) generation was 27.7% of the total generation (Alternator) capacity.
    The total shut-down had occurred because the INDUCTION GENERATION supply was excessive in times of small demand.
    Does this happening relate in any way to the INDUCTION GENERATION method of connection of Solar Voltaic inverters to the 50Hz Grid?
    I am aware that there have been occasions where Solar voltaic inverters have caused interruptions to supply.
    The cause was then, in 1950, the UNGOVERNED ENERGY percentage, and the over speeding of the engines that drove the Induction motors.

    Is there a case for providing “GOVERNOR DROOP CONTROL” on the large installations of PV & Inverter installations?

    Alan Swales

    1. Hi Alan,

      We’ve asked Nigel Morris of Solar Business Services for some assistance in answering your question. Here is his response:

      “I’m not an expert in generators, but have done a bit of work with them so here goes. Generators have to try and keep a constant speed and don’t like varying load, but that is what they face in the situation you described. Consequently, the power and voltage would droop under certain situations and if it got extreme, the generator could stall or the alternator would go so far out of synchronisation that it would drop off line.

      Solar systems have some similar characteristics, but it works a bit differently. The power and voltage form the solar panels can vary, but the inverter (which converts the DC from the panels to AC) smooths these fluctuations out, before producing AC and “power point tracks” to generate as much as it can under a wide variety of conditions. At dawn or dusk for example, when sunlight is very low, so is power and voltage, but the inverter will fire up and synchronise when sufficient voltage and power is available – as little as 50Watts is enough on most systems.

      The inverter then synchronises and tracks grid voltage and frequency, adjusting its output to match what the grid requires. There are very tight voltage and frequency windows that they are required to stay within for safety and reliability reasons and in some states they are also required to track reactive power requirements.

      Under normal conditions, the grid voltage (nominally 230V AC) droops as load is applied when businesses start up. Through a variety of means, network operators try to compensate for this droop to keep the voltage within an acceptable range.

      In some cases where there is a lot of power coming from lots of solar systems this can overwhelm this droop and can push network voltage up. This is tricky for network operators, but certainly can be managed with modern dynamic power control devices and sophisticated data logging. It is worst on long lines, SWER lines, in remote area’s or where the network has very little excess capacity in its power lines. In these cases almost everywhere in Australia, “export control” equipment is installed on solar systems that prevents excess energy from being exported and pushing the voltage up. IN this way, solar systems generate all their energy “behind the meter” and from the networks perspective, all they see is reduced load (demand minus solar generation). This is dynamically controlled in milliseconds to match the variation in load and generation.”

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