Rooftop solar panels: our new peaking power generators

Politicians are reacting because the increasing cost to consumers is finally being passed on to the ruling class in the form of a cost to their political capital. But amid the name-calling, the blame-gaming, the party one liners, and the ducking and weaving, comes the realisation that there are some seriously good alternatives. But what is not widely accepted is that many of these solutions involve renewables.

The common thinking among many energy experts and energy ingénues is that renewables such as wind and solar are intermittent and unreliable, and therefore cannot be relied upon for “baseload” generation, let alone switched on at will to meet the rising peaks.

The CSIRO would like to differ. In fact, says Glenn Platt, the head of the local energy systems team, distributed generation such as tri-generation and co-generation, but also in the form of rooftop solar, can play a crucial part in meeting peaking demand. Far from contributing to the problem, renewables such as solar can be harnessed to provide a solution.

“The traditional view would be to say that solar generation doesn’t have a huge part to play in peak demand,” Platt told RenewEconomy in an interview. “But if you look at peak demand on the wider electricity market, it coincides very well.”

The Australian Energy Market Operator noted in a report last week that in the state with the highest amount of solar PV, South Australia, where one out of five houses (twice the national average) have a rooftop system, 38 per cent of the solar output could be considered to be meeting peak demand.

Platt says the CSIRO has done internal research that across the NEM that suggests solar PV could make a huge difference to peak demand. In commercial instances, where a large office building installs solar on the roof, for instance, the matching is virtually on a 1:1 basis.

Designs for renewable-dominated grids usually describe the use of large solar thermal plants with 3 hours, 6 hours, or even longer storage, delivering the sort of despatchable power now provided by gas plants. These technologies still have some ways to come down the cost curve.

On a distributed, or local level, it is also certain that technologies such as battery storage and electric vehicles will add a new dimension to the challenges of meeting peak demand when those technologies are rolled out in the years to come. The EV, for instance, will be like a battery on wheels, and will be parked at home at the same time as the householders flick on the air-con and the TV and add to the power load. Batteries, including those in EVs, can be topped up using solar energy during the day for use at a later time.

But these are glimpses into the (not-so-distant) future, there are already solutions using current technologies and practices. Banking energy in the form of cold air (or hot air) can be achieved by cooling the air more than initially required while renewable sources such as solar are available, and turning them down when peak demand arrives.

This could be used just as easily with a fridge, as it can with an air conditioning system. Many houses use the same principal with solar hot water. Platt says CSIRO has produced research that a change of 1C in heat requirements can change energy demand by as much as 10 per cent – so by storing that cool air, or changing the temperature targets, could have a significant impact.

These techniques are being used on commercial buildings by a CSIRO spin-off called Building IQ. Its technology is already proving particularly popular in the US, where buildings can be pre-cooled and temperatures managed to avoid, or to respond, to peak demand.

The CSIRO is also testing the concept of a “virtual power station” that links a group of rooftop PV systems on a group of residential buildings and links them with battery. The website – which records the combined output of rooftop solar on 20 houses and council sites, and two battery storage installations in the Lake Macquarie district of NSW – can be found here, and some of the output can be found here.

Platt says the research is valuable. “We’ve been able to demonstrate that with sophisticated solar forecasting techniques, and a small amount of energy storage, a collective of rooftop solar panels can look to the grid just like a traditional fossil fuelled generator. So, instead of buying electricity for $12,000 a megawatt hour (as happens in some summer peaks), we can supply green electrons to the grid very quickly.”

The CSIRO is also leading research into solar cooling technologies. A recent report by the International Energy Agency said solar heating and cooling (SHC) could make a dramatic impact on the world’s electricity grids, providing 17 per cent of all energy required for heating in buildings, industrial processes, swimming pools, and 17 per cent of cooling needs, reducing the need for new generation and cutting peak demand in particular.

Like many of those in the industry specialising in demand management, Platt says “it is gratifying that the issue is getting some broader attention. We feel quite strongly that there are better way to do things. Peak demand is a real issue, and it is clear we are not doing things in the smartest manner – this is a genuinechallenge for the networks as well as consumers.”