Power to 2050, page-16

This was posted in a RFX forum by @starsky. I believe it is from today's AFR. Probably explains it better than I have.
Home battery uptake points to emergence of 'virtual power plant'
by Angela Macdonald-Smith
The vision of a "virtual power plant" made up of thousands of batteries connected to solar panels in individual households and communicating through smart digital technology seems somewhat futuristic but may not be so far away.
That concept took another step forward this week as two more battery hopefuls entered the Australian household market. They join a lengthening line-up of competitors from around the world going head-to-head in a market where sales of 80-100 units a month are expected to more than double by next year.
The ability to connect the batteries in a network means they could be called on by a power grid operator when electricity demand is high or during an outage elsewhere in the system.
Simon Hackett, technology entrepreneur and executive chairman of home-grown battery developer Redflow, predicts that in just three to five years, grid operators will start to offer customers who own home storage systems the opportunity to get paid to send energy back into the grid when the system needs it.
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Typical solar-battery household daily use (kwh)
"The way this is heading is a world where if there's a few thousand of these in a city, collectively you've actually got a power generator," Hackett says. "So rather than spinning up a gas-fired peaking plant somewhere, you can set the inverter in reverse and push the energy straight back into the grid on demand."
Hackett says while grid operators are some way away from being ready for such a new world, they can see the future lies in that direction.
It is already happening elsewhere, with news last week of a fleet of 20 solar and energy storage systems in homes in Ontario connected in a pilot project by Canadian community energy company PowerStream, providing the country's first virtual power plant.
Systems to send power back

Locally, intelligent control systems and software being being developed by start-ups such as Redback Technologies in Queensland and Reposit Power in the ACT that are specifically aimed at allowing households to send power back into the grid when needed.
The concept underscores the value of staying connected to the grid. Households with rooftop solar and batteries can avoid the huge extra expense of back-up power and extra storage capacity to be totally self-sufficient, while grid operators can avoid extra investment in system capacity that may only be called on a couple of times a year.
It also feeds into the thorny debate about network tariff reforms, and whether those solar and battery-equipped homes able to take themselves 95 per cent off the grid should pay a proportionally higher price for their reliance on it the rest of the time, which is likely to be just when the strain on the whole system is highest.
Hackett reckons not, given the value to the grid operator of being able to call on those home batteries when some extra generation is needed. Jacking up charges for those customers would only risk triggering a mass defection from the grid, pushing up costs for the rest as fixed costs are spread among fewer. Rather, he sees grid operators working towards a "two-way street", a trading environment where households can effectively trade with their neighbours.
The challenge is to get the pricing right on the grid to allow for that, potentially pushing up fixed costs for use of the grid, and reducing charges for actual usage. That would potentially allow those who don't live in homes with their own solar panels – an apartment, for example – to benefit too.
Going one step further, Hackett points to the potential for creative solutions on batteries that could also solve state governments' heavy forward liability for generous historical solar feed-in tariffs. A voluntary exchange of those tariffs for a battery installed by the government, for example, could save taxpayer funds while inserting valuable, externally controllable power systems into the new smart grid.