The Pleasures & Sorrows Of Tesla’s Powerwall: An Installer’s Perspective

SolarQuotes has sometimes faced accusations of lacking independence, with critics suggesting Tesla must be footing the bill for our positive coverage of the Powerwall. We’ve also been accused of rigging Tesla’s gold medal in our 2023 Installers’ Choice Awards.

Tesla owns SolarQuotes

— Laurie Kelly (@LaurieAnneMD) March 6, 2023

So, is Tesla’s home battery really that exceptional? Or is Elon funnelling Dogecoin to Finn in virtual brown envelopes?

Confession time:

I’ve never installed a Tesla Powerwall…

I have no firsthand experience with a Tesla Powerwall. I’ve never unboxed one, mounted it on a wall, or gone through the commissioning process.

Well, I’ve been to training courses, trade shows, and social events, and I know fellow installers who install Powerwalls. The consensus is clear: Tesla users and installers rarely have complaints. The Powerwall delivers on its promises; if it doesn’t, Tesla’s phone support sets it right.

The Powerwall’s Pleasures

Good Specs

Bad news travels fast, but the Powerwall has few critics. Its specs are solid; one model that you can expand by adding more units. And let’s be honest, when you have to stop at ten units¹, a more industrial solution is probably required.

Until that point though, the Powerwall has a good surge capacity and offers good storage size considering its small footprint. A solar inverter’s monitoring can be cluttered with details that only energy nerds find scintillating, presenting numbers that don’t affect your yield much but causing needless worry and support calls for reassurance that just aren’t needed.

Great Gateway

Tesla’s gateway backup box? A sleek, easy-to-install solution that adds a significant amount of electrical infrastructure. It’s got room to satisfy the needs of at least three significant-sized cables and circuit breakers for incomings and outgoings.

Tesla’s Monitoring App

The Tesla app is clean, full of appropriate information and intuitive; so in many cases the punters use it as their default home monitoring platform.

The Powerwall’s Sorrows

Tesla’s monitoring is so good it creates a new problem: many Powerwall owners ignore the monitoring that came with their solar inverter.

You Still NEED Your Solar Inverter’s Monitoring Alerts

In the same way RCD/earth leakage safety switches are now mandatory in your switchboard to help prevent electric shocks from appliances and light fittings, your solar power system has earth fault monitoring built into the inverter. If the electrical insulation of the array on your roof breaks down and DC electricity leaks to earth, the inverter will shut down.

The kicker is that the Australian Solar Installation Standard, AS/NZS5033 : 2021 mandates there shall be an actionable alarm that you will notice in the event of an earth fault.

I can make a case for a buzzer, which would be enough to prompt people to call the repair team. However, an email from the inverter monitoring platform is an acceptable solution, especially for remote building management. An SMS is even better.

If you have a solar power system, watching the red and green lights is important. Also, you should know what they signify.

If you’re new to the house, you may need a technician to attend and reconnect the monitoring of an existing system to the internet, which helps with warranty cover and legal requirements for earth fault monitoring. In some cases, it’s essential to prevent damage. For example, an Enphase envoy may brick itself if you leave it running for too long without an internet connection.

Three-phase limitations

The Powerwall cannot be used to give blackout-proof backup to 3-phase loads. You can back up single-phase loads. You can spread your single-phase loads across 3 Powerwalls, one on each phase, but the units will not operate in a 120° rotation. It’s a feature that the 110 volt peasants in Tesla’s home market don’t have any demand for. Whereas Fronius prioritise 3-phase equipment over single-phase because Austria has no single-phase connections.

No more support for off-grid

Powerwall is no longer recommended for off-grid use², so that’s a use case they don’t offer a warranty for. In fact, as a grid hybrid device, the Powerwall has also managed to disappoint a few customers who have found that while they can operate with AC-coupled solar to recharge during a grid outage, once the battery is depleted, they will not black start. The battery went flat overnight, and it would not recover and reboot in the morning.

Powerwall can limit your allowed solar capacity

One of the real features of the Powerwall (like any AC-coupled battery) is you can add it to premises with any legacy solar. It’s quite flexible in terms of being connected to a main switchboard or sub-board with wireless metering able to measure solar on different parts of the installation or phases. You can bolt it on anywhere, and it does its thing.

This flexibility proves problematic if your Distributed Network Service Provider (DNSP) deems the Powerwall’s integrated 5kW battery inverter as part of your 10kW connected inverter capacity; halting your ability to install the solar you need to charge the battery in the first place. In some instances, you can have 10kW of solar inverter and 10kW of battery inverter, but some more recalcitrant operators stipulate 10kW total.

For comparison, there are nominal 5kW hybrid solar inverters that offer a solar capacity of 10kW. Because the battery is DC coupled, the inverter can supply 5kW of AC loads in your house and charge the battery with DC straight from the array. You can claim STC incentives (AKA ‘the solar rebate’) for 10kW of solar³ instead of just the 6.6kW stipulated under the uniquely (silly) Australian rules. With AC-coupled systems, the rules prohibit oversizing the solar this way.

Powerwall Popularity Means Compatibility

Being one of the cool kids means you have more than a few options for connecting to external devices and services via Tesla’s Powerwall software interface⁴. Various virtual power plants allow you to buy and sell electricity with your battery and most of these can interface with the Powerwall. There are also smarts such as ChargeHQ that integrate your Powerwall and electric car charger to give you better control of where your solar energy goes.

It means that as anyone develops a new widget or killer app for battery, solar or energy management, they’ll ensure if possible it will be compatible with the ever-popular Tesla Powerwall. There are so many of them now that working with the biggest player is a commercial imperative.

In SolarQuotes’ 2023 Installers’ Choice Awards for solar batteries, Powerwall triumphed as the best home battery overall category for the third year in a row. It also grabbed 3rd spot in the “best value” (budget) category and was voted no.1 by installers for best after-sales support.

Original Source: https://www.solarquotes.com.au/blog/tesla-powerwall-installer-perspective/