{"id":34694,"date":"2019-11-04T11:07:43","date_gmt":"2019-11-04T00:37:43","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=34694"},"modified":"2024-10-03T09:35:29","modified_gmt":"2024-10-03T00:05:29","slug":"voltage-rise-solar","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/voltage-rise-solar\/","title":{"rendered":"Voltage Rise & Solar Shutdowns. Why It Happens & How To Fix It."},"content":{"rendered":"
\"Grid

Your grid voltage should average 230V. But it probably doesn’t.<\/p><\/div>\n

This time last week I was at the 2019 All Energy Conference and Exhibition in Melbourne.\u00a0 Or — if I have been lazy getting this article out — it was this time last week plus or minus one day. \u00a0Mostly plus.<\/p>\n

I attended a group presentation on grid over voltage. It’s a growing problem.\u00a0 When grid voltage rises too high, rooftop solar either reduces output or shuts down. \u00a0This not only costs solar households money but costs the country lives, as clean solar energy going to waste means more fossil fuel is burned, resulting in more pollution and environmental damage.<\/p>\n

While they do harbor a few complete grumps, the Distributed Network Service Providers (DNSPs)1<\/a><\/sup> that manage local grids do actually want to increase the amount of rooftop solar energy their grids can accept.\u00a0 The current levels of PV penetration wouldn’t be possible if they didn’t. \u00a0But the broken incentive system means there is too little emphasis on minimising losses from rooftop solar power systems.<\/p>\n

What Is Grid Over Voltage?<\/h2>\n

Grid over voltage occurs when the voltage in the power lines your home or business is connected to exceeds the Australian standard, which is 235 volts plus or minus 8%…<\/p>\n

Wait a minute…\u00a0 I think I can hear Finn screaming at me from the future when he edits this.\u00a0 I’d better jump forwards in time and check what the problem is…<\/p>\n

\"\"<\/p>\n

Are you sure?\u00a0 Really?\u00a0 But that’s just nuts<\/em>!\u00a0 Well, okay, I’ll tell them…<\/p>\n

\"\"<\/p>\n

It turns out Australia’s standard isn’t 235 volts plus or minus 8%.\u00a0 It’s actually 230 volts +10% or -6%, giving a range of 216.2 to 253 volts.\u00a0 You may be wondering why the plus goes all the way up to 10% and the minus only goes down to 6%.\u00a0 Well, that’s because Australia2<\/a><\/sup> really wanted to be able to say we had changed from our old standard of 240 volts down to the much more common 230 volts that is an international standard.3<\/a><\/sup><\/p>\n

The downside is it’s really difficult for a grid designed for an average of 240 volts to get down to an average of 230.\u00a0 We only had two sensible options:<\/p>\n

1.<\/strong>\u00a0 Do the hard work and spend the large amount of money required to make the change.<\/p>\n

2.<\/strong>\u00a0 Admit there would be a long transition period where the voltage would average between 230 and 240 volts.<\/p>\n

So, of course, we instead decided to:<\/p>\n

3.<\/strong>\u00a0 Half arse it.<\/p>\n

We lowered the average voltage as far as it would easily go with existing grid infrastructure and then claimed to have met the standard by abusing the concept of plus or minus and allowing a big plus 10% with a considerably smaller minus 6%.<\/p>\n

We’ve been slowly working our way down further as old equipment is replaced.\u00a0 At the current rate, in South Australia, this process will take around 250 years.\u00a0 Mind you, we’ll have to pick up the pace at some point when aging equipment starts falling apart.<\/p>\n

Being stuck with a grid that was built for 240 volts and then using up most of the flexibility in the system to get the average halfway down to 230 volts is a major reason why grid over voltage is such a problem.\u00a0 There’s not much “give” left in the current hardware to easily allow voltages to be lowered further.<\/p>\n

This is rarely mentioned in discussions of grid over voltage and wasn’t specifically brought up at the presentation.\u00a0 Possibly because the speakers were all so young and the decision to move towards changing the standard is ancient history to them.4<\/a><\/sup><\/p>\n

Grid Over Voltage Shuts Down Solar<\/h2>\n

Electricity flows from higher voltage to lower voltage.\u00a0 This means if the grid voltage is higher than the voltage produced by rooftop solar, that solar power system will be unable to export energy.\u00a0 While solar inverters could be designed to always beat the grid on voltage, this would be very naughty because it would push the local voltage higher and could cause electrical devices throughout the neighborhood to start smoking.<\/p>\n

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A smoking electrical device.<\/p><\/div>\n

To prevent a bad situation getting worse, solar inverters will shut down once grid voltage reaches a set limit.\u00a0 Usually, older inverters have higher set points while most modern ones can reduce their output gradually as grid voltage rises.<\/p>\n

What To Do If Grid Over Voltage Shuts Down Your Inverter<\/h2>\n

South Australia Power Networks get over 10 complaints a day about grid over voltage.\u00a0 In August, Richard Chirgwin wrote about how the problem is getting worse<\/a>.\u00a0 He reported that, according to Solar Analytics, 50% of their customers had their solar energy reduced or shut down at least 50 times a year.\u00a0 That’s an average of about one or more times a week, although these events will be less common in winter when solar output is lower.\u00a0 For solar homes in particularly bad locations, grid over voltage can easily cost them hundreds of dollars annually in lost generation for an average sized system.<\/p>\n

Fortunately, there are things you can do.\u00a0 The DNSP in charge of your local grid has a statutory obligation to prevent over voltage.\u00a0 That’s a fancy way of saying if there is a problem they have to fix it.\u00a0 While it may not be reasonable to expect the grid to always get it right, if lost solar electricity production ever becomes more than a mild inconvenience thanks to grid over voltage, it should be fixed.<\/p>\n

But an over-voltage error on your solar inverter may not be your DNSP’s fault. It could be caused by your solar installation or your existing grid connection. Specifically the wires from your inverter and switchboard through to your grid connection point may have too high a resistance. This can be caused by distance, thin wires or bad connections. Your installer should check your home’s voltage rise before installing but, unfortunately, many do not.<\/p>\n

How To Diagnose The Cause, Then Fix It.<\/h2>\n

So how do you determine if your voltage rise issue is caused by your installation, your grid connection or your DNSP?<\/p>\n

Finn has written step by step instructions on how to diagnose the cause and what to do about it<\/a>. If you have a grid over voltage problem, ask your installer to follow those instructions step-by-step5<\/a><\/sup>.<\/p>\n

4 Speakers +25% \/ -0%<\/h2>\n

There were 4 speakers plus 25% minus 0%.\u00a0 Actually, it would be clearer to explain there were 3 individual speakers and one presentation by a duo baritone and soprano.\u00a0 They were, in order:<\/p>\n

    \n
  1. James Sturch:\u00a0 Technical Director for Sonnen Batteries in Australia and NZ.\u00a0 Sonnen has a factory operating in Adelaide where they assemble battery systems.<\/li>\n
  2. Travis Kauschke:\u00a0 Senior Engineer at South Australia Power Networks.<\/li>\n
  3. Tom Langstaff from Ausnet and Claire Cass from CitiPower\/Powercor.\u00a0 Both from Victoria.<\/li>\n
  4. Candice Horig:\u00a0 Distribution Standards Network Officer for Energy Queensland.<\/li>\n<\/ol>\n

    I’ll go over the main points raised but not worry about the details of exactly who said what, as it is ideas that are important, not people.6<\/a><\/sup><\/p>\n

    Solutions for grid over voltage covered three main areas:<\/p>\n