We’re are back home in Emerald and have power!

The grid is still out, and is expected to be down until mid next week. But our house is getting power from solar and our Tesla Powerwall battery.

Driving back home (after our road trip to NSW), we could see why Emerald is still in the dark. Many power lines (and phone/broadband lines) are still down. Emerald featured in the first story on last night’s (Friday) ABC news:
https://iview.abc.net.au/show/abc-news-vic

At least one of our neighbours is running a fuel generator. Another has a couple of solar panels hooked up to a car battery for night lights and a 12V car fridge. Schools are effectively closed. The local petrol station had one pump going, with a long queue.

We have offered our neighbours electricity from our solar/battery power. One family had no power for three days, but now we have connected some extension cords over the fence.

History:

The grid died on Tuesday 14th. We were away road tripping in NSW. Our Tesla Powerwall battery continued to provide backup power to our house (and a few devices plugged in by neighbours). But the solar production cut out, no longer charging the battery. The battery slowly depleted over two days until no charge remained.

We contacted the installer, Lightning Energy, as soon as the problem occurred, but had no followup. After a frantic text message, Andrew very kindly dropped by on Thursday evening on his way home from work but couldn’t resolve the issue.

Yesterday (Friday) afternoon, a technician (Liam) from Lightning Energy came by to fix the issue. After a few hours of us tweaking it, the system started powering up again.

Technical details:

On Thursday we headed back from NSW, arriving yesterday (Friday) afternoon. Liam, a technician from Lightning Energy, arrived just before me. He discovered that one wire was missing from the installation that communicates from the Tesla Powerwall to the Enphase Energy Envoy solar control unit to tell it to keep going during an outage. Five minutes to fix that. Our house had power again!

But we couldn’t monitor the system, to see what was working. It had no network connection.

The broadband was out of commission in Emerald. The mobile cell reception was limited. The Powerwall battery and solar Envoy system were communicating with our home wifi router, but the router had no internet connection.

We were avoiding resetting the Powerwall, in case it stopped working again.

So, I turned off my home wifi base router and set up my iPhone as a hotspot with the same name and password – basically making my iPhone impersonate the wifi router. It worked! The Tesla Powerwall and Enphase Envoy solar controller appeared on the interwebs so we could monitor them through the apps.

The Tesla app showed the solar producing only 0.3kW, all of which was being consumed by the house, mainly the fridge. The Powerwall was not taking any of the power and the solar wasn’t ramping up to supply it. We briefly tried adding more load, by turning on a heater, which just started draining the Powerwall.

We wondered if we needed to kick start the Powerwall by giving it a temporary external power source to make it think the grid was back on line. The Tesla app and other info sources suggested that after the Powerwall is depleted, a grid connection is required for it to restart. The technician did not have any equipment to do this. I thought they would carry a 12V to 240V inverter or similar for this purpose. He said that a petrol generator provides choppy power that would be a risk, and that any external source would probably need to be wired directly into the switchboard.

This was looking pretty sad. What’s the point of having a Powerwall if I’d need a generator to kick it over?

Anyway, it turned out that none of that was needed!

After the technician left, I tried powering off all of the house load, at the switchboard. The 0.3kW production started diverting to the battery. Hooray! But 0.3kW is way too slow. Why wasn’t it producing higher? To my pleasant surprise, after a few minutes the solar production gradually increased, all consumed by the battery, from 0.3kW to eventually near 2kW. The Powerwall charge climbed from 0% to 1% and kept going. I turned the house circuits back on, such as the fridge. The solar production continued. We were back in business!

By the time the sun set, we had 25% battery charge. Overnight, the house (mainly the fridge) used 10% (1.3kWh) before the morning sun started charging it up again from about 8am.

Today, the solar reached a maximum of 3.9kW production. It turns out that during a grid outage, our solar system is currently set to only enable one string of solar panels (3.9kW) rather than the full array (10kW). I presume that this is to stop it producing more than our Powerwall (5kW max) and house can consume. But, when the Powerwall is eventually fully charged, it will need to ramp down the solar anyway 🤔.

Now that I know that, if I want to limit solar production while I’m away next time, I’ll enable string 1, rather than string 2. This time it wouldn’t have worked anyway, due to the missing wire.

So, we have enough power to keep our house going, fully charge our Powerwall battery, and help the neighbours. But we can only slowly charge our car. This will be the next problem to solve.