Cyclone Alfred: What To Do With Your Solar And Battery

As everyone will be aware, Cyclone Alfred is bearing down on some pretty populated parts of Queensland and New South Wales. Solar installers have been posting useful links, so without adding to the information overload we’d like to put a few of the best tips we’ve found together.

If You Have Standard Grid Connected Solar

Energex are putting out blanket advice to turn your solar power off. It’s really not necessary and it’s really pissed off the installer industry in Brisbane because the phone just won’t stop ringing.

AS4777 mandates that when the mains power goes off, so does your inverter. It’s not essential to turn solar systems off.

Unless your system has a rooftop isolator, (which nobody should be looking for in 100km/h winds) switching the DC off at the inverter really doesn’t achieve anything. By disconnecting the safety functions for earth leakage inside the inverter, arguably it makes the system less safe

To quote Brisbane Solar Repairs; Your inverter is a very clever bit of machinery – it can detect when the power is out or the grid has become unstable and turns itself off without any intervention by you.

Turn The AC Off First; Then The DC

Of course, if it makes you more comfortable you can shut the system down as a precaution.

It can be worthwhile if there are likely to be lightning strikes, power poles blown over or trees striking power lines.

In each of these scenarios, you could have a monumental voltage fed down your street. Trees can drop feeder lines, crossing them with the 230 volt street distribution system, causing a sustained injection of 11,000 volts, while a bolt of lightning may be a million more volts.

However the general advice is to have a battery-powered radio tuned to ABC local and put some ice in your freezer to transfer into the fridge if the power goes out.

This has kicked off a storm of needless fear and unnecessary phone calls

Energex may have reasons for telling people to turn off solar, but they’re not explaining it properly.

Using temporary HV generators or piggyback network feeders, deployed as stop gaps when trying to get things back up and running means network stability can be difficult.

However, Energex’s explicit instruction to people with batteries to turn off the DC solar for “safety” reasons is just wrong.

If You Have A Battery

Lucky you: it’s worth testing the blackout function (assuming you have that option enabled at install time) by turning off the mains power.

In your main switchboard there should be a “Main Switch Normal Supply” or “Main Switch Grid Supply” or perhaps “Meter Isolator” and these should be a different-coloured label to all the rest.

Turning off the supply from the street simulates an outage so depending on your system, the lights should stay on, or they may take up to 40 seconds to come back, accompanied by a clunk from the switchboard.

Batteries May Need Some Management

Thanks here go to Scott Su at Sungrow, who has been proactive on social media in explaining how to make sure you have a full battery before the grid might go down.

Follow the red highlights to navigate the app and make sure your battery is fully charged, or try the YouTube guide here.

• First up, find the account for your installation or property

(this is an administrator screenshot so you may not encounter this view on your consumer monitoring)

• Bear in mind the apps can vary with age and installed hardware
  • Scott says Select “Menu” to expand the technical settings
  • On my own Sungrow app I have to select “Device” to get to the next screen
    (where it says “Dashboard” in this image)

Standard three bars for MENU

• Select the “Hybrid Inverter” or “Energy Storage System”

Your system may have more than 1 inverter listed.

• Slide the top bar across to find the “Settings” tab, then tap “General Settings”

There are a lot of settings, consult your installer or possibly youtube if you’re in doubt.

• Set your battery reserve to 100% so that remains fully charged unless the grid goes missing
  • ie “Please Enter 100”

Backup mode should already be enabled provided the house has been wired for it of course.

This is a good example of the process, but Sungrow promise us they’re working on a more user-friendly toggle on the home screen to make this much easier.

Of course, if you have a different brand of solar hardware, the monitoring will look different, and there will be a different procedure.

For instance Tesla has an option called “Stormwatch” which is designed to make this battery charging happen automatically, however if you have other controls such as a retail deal with Amber or are part of a Virtual Power Plant, these might need to be disabled so you have complete control of the battery.

If You’re Wading Out Of A House That’s Going Under

Nobody is making light of this situation but the inimitable John Ingliss from Geebung’s own Positronic Solar has a very helpful video posted to Youtube.

Bear in mind this is pragmatic advice for competent people. The authorities would consider it electrical work that should legally be undertaken by trained electricians. As these qualified people are in short supply during an emergency, you may undertake these tasks at your own risk.

In this video he outlines how to deliberately short-circuit your DC solar power and render it safe by clamping the voltage to zero.

Using a clear path to circulate current is actually a safety feature employed by some inverter makers like SMA, to deal with potential earth faults.

This is quite safe to do because the wiring for DC solar arrays is drastically oversized to minimise losses. Solar panels are a current-limited source so they simply can’t overheat the wiring which is rated for double or triple the working load.

Disconnecting the AC source is no guarantee but it does mean there’s less chance the inverter will be damaged if it does suffer some moisture ingress. Disconnecting and shorting the DC will prevent the possibility of an internal inverter fire in the hours and days after the water recedes.

HOWEVER THERE IS AN IMPORTANT CAVEAT

• Since this video was recorded, most solar inverters have moved to having an onboard DC isolator inside the inverter.
• If you wish to short the array for one of these modern units, it would be best to do the work at night, as the DC solar plugs will be live when you’re trying to remove them from the inverter and connect them together.
• Separating or fumbling with live plugs will cause a significant DC arc flash, blackening and melting the pins and possibly burning your fingers and singing your eyebrows.
• If you’re in any doubt, leave well alone, it’s not worth taking the risk.

Energex Has Advice; Not All Of It Is Good

If you go to their website, there’s some general precautions in a pdf and a web page with fairly sound reasoning.

However, the blanket advice issued on social media to shut down solar power systems is causing needless fear, uncertainty and doubt.

The take-home message is:

1. Treat solar power systems and components with respect, especially if they might have been flooded with water.
2. If you have a power system that is likely to be inundated, get professional help to isolate, move components and short the array.
3. Have your system inspected and recommissioned by a qualified installer once the weather has passed.

The fine print in your network connection agreement will specify a periodic inspection by an electrician, usually at intervals of not more than 5 years, so take the opportunity and make sure everything is good for the coming season.

Only Going To Get Worse

Though it’s been 35 years between drinks, it’s not unprecedented to have cyclones impact New South Wales, however it’s the excess rainfall and resulting floods which prove most damaging, according to the insurance industry.

As we trap more energy in the climate system with a blanket of carbon in the atmosphere, extremes of weather like this storm become more common and more powerful. There’s no debate, it’s not a matter of believing in climate change, insurers are repeatedly sticking their hands out for government subsidies.

Regardless of whether you are in the firing line of Alfred this time round, its worth getting to grips with what to do with your solar and battery system should a heavy storm come your way, since it is getting ever more likely that one will.

I just hope that maybe those lamenting even the AFL season opener had to be cancelled will begin to pay attention. If the football is being affected then this is getting serious.