Jun 27, 2019 - 7min read
Tesla Powerwall is not only a thing of beauty, it also has the smarts. Designed with an unparalleled sense of precision to make the most of renewable energy generated by your solar panels, it’s why we’ve chosen it as the only home battery we offer and install for our members.
And if you’re a bit of a geek like us, then get salivating with 10 awesomely nerdy facts about the Powerwall brought to you by renewable tech expert Richard Sloan, from our award-winning in-house installation team The Phoenix Works:
“As a single unit,” says Richard, “it’s the largest capacity domestic battery available.”
Let’s put that 13.5kWh into perspective. “The average reasonably energy efficient household on gas central heating and gas cooking will be looking at using 7kWh a day, so Tesla Powerwall’s capacity will more than cover that.”
Obviously, that figure will be higher if you own an electric hob and cooker, and certainly if you’re on electric heating, but given that the average UK household uses 10.4kWH of electricity per day, a single Tesla Powerwall is well-positioned to surpass the needs of most households.
The capacity of all batteries will fall over time, and for smaller batteries, this can present a real issue. The fact that Tesla Powerwall has such a large capacity to begin with, and a power warranty of 80% energy retention after 10 years, means that even after a decade it will store more than enough energy to power the average household for a day.
"It also has 5kW charge and discharge,” says Richard. “If you think about charging the battery from your solar panels, then depending on the size of your solar system you’ve got the ability for the battery to potentially absorb everything that’s coming from the solar, in terms of recharging it.
“The same goes for discharging the battery. You’ve got that same 5kW continuous output. The average kettle is 2.5/3kW output, so - as an illustration - you would theoretically be able to boil two kettles continuously."
“It’s relatively slim, not far off the depth of a double radiator,” says Richard. “Tesla has designed it primarily with a garage internal wall in mind, so you’re not impeding on getting a vehicle in and out. You haven’t got bits sticking out of it - it’s a very sleek, simple design. A very smart rectangular box on the wall.
“And if somebody wants to show it off then they can be mounted outside as well. There are customers out there who want their neighbours and visitors to know they’ve got a Powerwall!”
“You can connect up to 10 Powerwalls in series to store a total of 135 kWh of electricity,” says Richard, “which is obviously more than the average home would ever need!”
Tesla has made this possible so that it’s easy for considerably larger properties or small businesses to scale up their battery storage where necessary, though the vast majority of homes will never require more than the already considerable 13.5 kWh capacity of a single Powerwall.
“It’s pretty heavy, which is why it’s a two-man installation. Because of what’s in batteries, they are inherently heavy. It’s made up of multiple lithium-ion cells, which will constitute quite a lot of that weight. It’s heavy, so it stores more energy - the two kind of go together.”
Tesla Powerwall is able to operate in an unusually high range of temperatures, thanks to Tesla’s unique liquid thermal management system that regulates the battery’s temperature.
“Whether the battery is charging or discharging, it’s going to be generating heat. Tesla Powerwall is self-maintaining, from that point of view,” says Richard. ”The operating range of -20C to 50 C gives you the extremes of the ambient temperature around the battery. The selling point for the Powerwall is that it controls itself temperature-wise within these extremes and doesn’t rely on having cold air blasted at it.”
“I’ve never noticed any sound from the Powerwall. The sound-absorbing foam would be around the cooling system, which is the only thing that would be making a noise.”
“The battery has a second unit as part of the installation which is a piece of hardware called the Gateway,” says Richard. “This is really the brains of the Powerwall - separate from the battery itself, which is all about storage, the cooling, and the electrical connection.
“The Gateway has a couple of monitoring points, so it knows how much solar is being generated at any particular time, and it knows how much demand there is in the house at the same time. It has an internet connection via the user’s internet router or hub, and it has a connection to the battery so it can monitor and control what the battery is doing at any time.
“When the system is set up we tell the Gateway where it is in the country - we give it a location and an address. We also tell it the size of the customer’s solar PV system. From that, Powerwall will look ahead at the predicted weather for that location, and make a prediction as to how much energy the solar is likely to generate the following day. Alongside that, it looks at the average consumption profile of the home - having gone through a learning phase. It then gets weather information from Tesla’s central system, compares that to a prediction of the homeowner’s consumption, and can adjust its operation accordingly.”
“Self-powered is the mode that most people would expect to use,” says Richard. “You’ve got solar panels on your roof and they’re generating electricity during the day. Any demand in the house will be met by energy from the solar first before using anything from the grid. If the house isn’t using all of the energy generated by the solar, the battery will say ‘Ok, I’m not fully charged, I’m gonna grab that power.’ Once the battery is fully recharged, only then will it send any of your free electricity back to the grid.
“Come the end of the day, when you’ve got no solar being generated, you can start to draw off the Powerwall capacity, instead of drawing from the grid. If you go onto the Tesla App, you get live visibility of what your house is using, how much your solar is producing, how much you’re drawing from or sending back to the grid, how much is stored in your battery, how much you’re drawing from your battery and how much you’re recharging your battery.
“Advanced Time-Based Control is a mode you can use if you have something equivalent to an Economy 7 tariff. You have the ability to tell the battery that it can recharge from the grid during the cheap electricity rate - so it can be programmed to recharge at certain hours by the customer. If you get very cheap electricity at night, the battery can use it’s weather predictions to calculate whether it will get enough solar the following day, and can top up with cheap night-time electricity so as to be fully charged in the event of below-average solar generation.”
“Grid Services are in the pipeline, which means Tesla Powerwall owners will one day be able to automatically buy and sell energy to the grid,” says Richard. “This helps the grid in its constant battle to match supply and demand, and can open up new income opportunities for Powerwall owners."
By getting a Powerwall today, Tonik members will be well placed to make the most of these opportunities as soon as they arrive.
Tesla Powerwall is about preparing for the future, but its outstanding tech specifications mean it also provides immediate, major benefits in the here and now - especially when working together with solar PV.
“Tesla don’t do any advertising, yet their cars are seen as the prestige models,” says Richard. “It’s exactly the same battery technology going into the cars that’s going into the Powerwall, and the high capacity is what gives Tesla’s cars their excellent range”
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