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Author: Tristan Edis
Source: Climate Spectator
Date: 21 May, 2013 

Yesterday I wrote about how the energy supply industry association, the ESAA, had inappropriately demonised solar households for far broader problems associated with how electricity is regulated and priced. 

But this was not the only misleading aspect of its paper – Who Pays for Solar Energy. It made the following claim that needs to be nipped in the bud before the myth becomes accepted as fact:

Household solar energy has had an impact on the cost of maintaining the electricity networks. In some areas, there’s been so much solar energy installed that network providers have had to spend millions of dollars in upgrades to cope with increased supply of electricity into the grid.

“Millions of dollars” – sounds impressive. To the layman or a tabloid journalist keen for another cost of living beat-up it sounds like an awful lot of money. But such vaguely specified amounts coming from an industry association should sound suspicious.

I’ve heard this claim of large amounts of money being spent on network infrastructure upgrades to accommodate solar PV several times. In all cases it involves very little in the way of concrete examples and specifics.  

For example I remember Western Power’s CEO, Paul Italiano, spouting it last year. At the time I was rather puzzled because his own organisation had undertaken a trial involving high amounts of solar PV which came to a different conclusion. This trial involved a single transformer where 40 per cent of households it serviced had solar PV systems installed (compared to the 11 per cent national average).  This equated to 27 per cent of the rated capacity of the transformer. Such high penetration levels for solar do occur in other places, but they are rare.

The study found that large amounts of solar PV can lead to noticeable rises in the system voltage but at the transformer level they, “remained well within the ± 6 per cent planning criteria established in Western Power’s Technical Rules.”  It then looked at voltage levels at several individual customer premises downstream of the transformer utilising smart meter data. This found that at least one had voltage outside guidelines (but below levels that would cause damage to appliances). However according to Western Power:

From these preliminary results it is clear that a relatively simple adjustment on the distribution transformer tap to a lower level, could allow somewhat larger solar PV system penetration on this network while still maintaining voltages within limits for customers at the end of the L[ow]V[oltage] network.

For those less technically minded, a “tap change” is little more than a manual adjustment to a lever or switch on the transformer that adjusts the voltage of the electricity that flows out of it. It doesn’t cost a million dollars or even thousands to change.

Pointing out the results of this study, I asked Western Power’s CEO if he could elaborate on specifically how solar PV was causing the need for costly upgrades and how prevalent these were. He wasn’t able to.

The ESAA was also asked by Climate Spectator if it could provide a more detailed quantification of the cost and specific examples where solar PV was driving upgrades to network infrastructure. At the time of writing ESAA hadn’t managed to uncover some specific examples nor provide a more detailed explanation of the “millions” being spent on upgrades.

Now of course it is a technological certainty that if a large enough amount of solar PV is installed in a given area, then it will require more expensive solutions than tap changes.  

But guess what?

Network businesses place constraints on the ability to connect solar PV where they expect this might happen. To illustrate you don’t have to look any further than the Energex website where it states:

What do I do if I wish to increase the capacity of my PV system?

Please ask the installer completing the upgrade to contact Energex for re-approval of the higher capacity before work is started. In some cases, our network may not be able to safely accept a higher level of generation.

Technical staff within the network businesses and solar installers will tell you that in areas with high penetration of solar (ballpark is where PV installed capacity represents around 25 per cent to 30 per cent of the transformer’s capacity, but varies depending on network condition), restrictions are placed on the size of a system you can install, or whether you can install a system at all. Before connection approval is granted the network undertakes a technical assessment of whether the infrastructure can accommodate it without harming power quality. 

If they think upgrades are required the odds are the person who wants to connect their solar system will have to pay.

For much of Australia we are still a long way from reaching 25 per cent+ penetration of solar PV, so there’s plenty of room for growth without incurring material network costs.

So next time you hear someone claim solar PV is costing a large but vaguely specified amount in network upgrades, ask them: precisely how much, when, and why?

Read article in Climate Spectator