'Tip 1' for Direct Action: Making a million solar roofs matter

This is the first part in a series of 'Tips for Direct Action'.

One of Greg Hunt's favourite Direct Action lines is to repeat his party's support for "one million solar roofs". In recent times he has updated his policy to "an additional million solar roofs". This is because the country already has over one million solar households.

If implemented and targeted properly, an additional million solar roofs could be really worthwhile in the transition to a 100 per cent renewables powered zero emissions economy.

With such a good start, how can we make Greg Hunt and Tony Abbott's government support for another million houses count?

Economies of scale: bigger systems

All those households that have solar today benefited from a federal government scheme which artificially capped domestic solar systems at 1.5kW. It costs money to ship equipment to a site and whether you ship lots of equipment or a little equipment it doesn't change the cost much. Same goes for the cost of labour, you've got to get the installers to site, get an inspection and possibly change the meter,. If you install a lot more panels and a bigger inverter the cost goes down per kilowatt of capacity and, consequently, the cost of energy produced is less. Systems that are backed by a government scheme should be a minimum of 5kW unless there is not enough north, east or west-facing roof space to support that size system.

Storage

Coupling storage with solar photovoltaic installs has a dramatic effect on reducing grid costs and the cost of provisioning peak power (with wide enough deployment it would eliminate it for good). Commercial storage options already exist with advanced battery management that can shift solar from daytime to nighttime, dramatically improving behind-the-meter economics in a post feed-in tariff world. Storage systems can also help with grid support. 

Oversizing

Systems that are oversized – where the solar array has a greater rating than the rating of the inverter – must be supported. Government support should extend to adding more panels to 5kW systems to enable them to produce a more uniform daily output (less of a bell curve) oversizing can include installations where an array exists facing north and additional arrays face east and west – i.e. at the upper limit of what should be supported, a household may have 10kW facing north, 6kW east and 6kW west all running through a 10kW inverter (with oversizing some production is, of course, lost to clipping – usually on a hot long sunny summer day). 

Where oversizing should be mandated is where the grid operator will not allow an inverter that is at least 5kW to be installed due to the customer being on a rural feeder and not being coupled with a storage system that can isolate production from the grid. In this case a customer may have a 3kW inverter and have 6kW of solar PV installed producing a similar amount of annual electricity as a 5kW system. In addition, under these restricted rural feeder scenarios the customer could be further incentivised to include storage, such systems coupled with active connectivity to smart meters will be programmed with a virtual capacity to not exceed set limits feeding back into the grid – i.e. customer has a 10kW inverter, however the inverter will never inject more than 3kW into the grid beyond the meter by monitoring the smart meter in realtime. This reform would have the additional benefit of allowing remote customers to upgrade their effective supply kW capacity locally without spending tens of thousands, or hundreds of thousands, on getting their poles and wires upgraded.

Upsizing and upgrading existing systems

In co-operation with the states, Greg Hunt should direct the states to agree to a cap on feed-in tariff payouts based on the maximum possible that can be generated under each scheme – i.e. 5kW limit in Victoria, 10kW limit in NSW. Then those households can participate in Direct Action and do their bit to reduce Australia's greenhouse emissions by installing more panels and additional, or bigger, inverter systems preferably coupled with storage systems as well as oversizing.

Grid support reactive power and power conditioning

Grid support in terms of reactive power is now part of the new grid connect standards in Germany. This technology and know-how from Germany can be easily transferred here. Power conditioning (usually coupled with storage systems) will improve the quality of power for rural people, mostly farmers who live at the end of SWER lines and other rural feeders, and would be a great place to support.

Solar appliances decoupled from the grid

The following solar appliance classes should be supported to directly reduce emissions at the source:

– Inverter reverse cycle air-conditioners hybridised with direct coupled photovoltaic

– stand-alone solar photovoltaic solar photovoltaic pool pumping

– Domestic tank water pumping hybridised with solar PV

– stand alone solar photovoltaic stockwatering/irrigation water pumping

– Heat pump hot water systems hybridised with solar PV

All this can be done with a bit of foresight, pushing the envelope to create new and better markets for the technology. If the additional one million house Direct Action policy was achieved targeting the kind of system sizes mentioned above (i.e. an average of 7-10kW per abode) then Australia could have an additional 7-10GW of solar photovoltaic on domestic rooftops producing between 9TW and 13TW of annual electricity (around 10 per cent of the nation's annual electricity). 

Greg Hunt and Tony Abbott, over to you.

Matthew Wright is the executive director of Zero Emissions Australia.