Electric cars and demand charges – the storage imperative

One of the biggest barriers to Solar PV’s success in commercial applications is the fact that it only reliably replaces kilowatt hours, which in some instances are as low as six-to-eight cents for the customer to purchase. The entire economic benefit of solar can be destroyed by the occurrence of the monthly demand peak when the sun is not shining.

It is generally now known that that most of Australia has it’s peaks in summer, due to the high uptake in domestic air conditioning over the past decade. Solar in the main has had a beneficial effect on reducing these network peaks, which in theory should reduce overall network costs, though this theory is yet to be seen in practice.

The most significant load in shopping centres and other commercial properties is HVAC, primarily air- conditioning, this followed by lighting and refrigeration. In order to increase the effectiveness of solar, the ability to store energy, in the form of heat or cold presents as an effective demand reduction strategy as energy peaks move into evening hours.

This strategy is now gaining traction throughout the retail sector as landlords struggle to retain viable chain and specialty stores suffering low sales, increasing on-line competition and spiraling overheads. No longer can landlords simply hump costs onto tenants, the landlord now has a vested interest in keeping the tenants business not only viable, but profitable.

Chilled water systems can now be boosted by tanks of super chilled fluid allowing refrigeration units to be operated during peak solar production and disconnected to reduce peak demand costs with little or no effect on the amenity of the complex.

Like- wise solar can charge thermal masses or liquid for heating in winter, a new imperative with rising gas prices. As it stands, solar PV with thermal storage is can provide a 20 percent plus R.O.I. to shopping centre owners.

Electric Cars product an entirely new challenge. Cars such as the GM Volt and Tesla “S” are ready to take over our streets and highways, like CD’s, and MP3’s this evolution will occur at a surprisingly fast rate. With charging stations rated at up to 100 kilowatts. With the logical demand for these to be available at our local shopping centres, how do we prevent these stations from blowing peak charges into the stratosphere?

A single Tesla supercharger is likely to cost $3000.00 per month in demand charges alone, with at least another $1000.00 in energy charges. This translates, in simplistic terms to a $16 per cost for each vehicle charged, even at lower charging rates, multiplicity will have an identical effect.

The only way to deal with this situation is by storage of electricity, not as simple or cheap as store thermal energy but getting there. Due to the reasonably short cycling of this type of storage, lithium batteries seem the most cost effective at present with the equivalent of 100KWH of storage available at around $60,000.00, with a five to six year useful life.

The delicate dance of reducing monthly demand charges, without interfering with the operation of a retail complex has not been a priority for centre owners, as they have been able to shift this spiraling cost on to customers. Queensland is due to bring in KVA charging this year.

The prospect of some complexes facing 10-15% energy costs is likely to spurn a massive rethink of energy generation, quality and storage in order to prevent what used to be a minor overhead from crippling the whole retailing model. It is both a challenging and an exciting time for large consumers of electricity, even those without giant swathes of roof-space have means to reduce the effect of demand pricing using storage.