UC researcher shines a light on the economics of solar power
June 25, 2013
A University of Canterbury (UC) researcher says despite a drop in price, the economics of domestic solar power is still
questionable.
Dr Alan Wood, a senior electrical and computer engineering lecturer, is exploring the economics of solar electricity for
the householder as part of a $6.3 million projected funded by the as part of a Ministry of Business, Innovation, and
Employment.
Dr Wood has developed a model which considers all the costs, income opportunities and the sunlight resource to calculate
a financial return for solar electricity.
``Unfortunately, these calculations are not straightforward for a domestic householder to make independently from their
system installer.
``This discourages householders from investing in solar electric systems. Our calculations show that it is not a
financially worthwhile investment for a typical house. However, this is not a general result, and in some cases it could
be worthwhile.”
Other than the panels, costs include installation, building consents, distribution company applications, electrical
wiring and inverter technology to feed the solar power into a house’s 240 volt supply and into the grid. Total costs
could be $10,000.
``Unless there is a need for air conditioning, domestic electricity consumption is typically low during sunshine hours.
Battery storage is expensive and we estimate the cost of cycling energy through batteries to be on a par with the retail
electricity price.
``An alternative is to store solar energy as heat, by heating water in a domestic water cylinder when the sun shines. In
some ways this is similar to the solar-thermal systems already available.
``Although a solar electric system dedicated to water heating is likely to be more expensive than a solar thermal
system, it should have some reliability and maintenance advantages. Our results show that using solar electric panels
and storing the energy as heat should have a positive net present value, although such systems are not yet commercially
available.
``Storing solar energy in hot water cylinders reduces overall electricity consumption, but can actually increase the
peak demand of households. This is because with solar water heating, there is no incentive to remain on an electricity
rate that allows control of hot water heating through ripple control systems.
``On cloudy days, remote control of mains-electric heating of hot water would be lost. An increase in peak demand means
a stronger electrical supply system is required, increasing some system costs.’’
Dr Wood is developing an on-line model which will be available to all New Zealanders for them to assess potential
returns of solar power.
ENDS