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    April 24

  • 12:43 PM

Tesla’s power play


Added 03 December 2016


Jerry Franklin is managing director of EnSmart Inc. (FILE)

TESLA CONTINUES TO push the barriers of our reality today, with the announcement of the Powerwall 2 and the Solar Roof. These are not new technology, but rather existing technology being made more accessible and more relevant to today’s environment.

Tesla boss Elon Musk evoked the imagination of the masses with the launch of the first Powerwall. Now he is showing that he is here to stay and that he is serious. Tesla listened to the feedback from users and installers of the first Powerwall and evolved the design to the new Powerwall. This new Powerwall has the potential to take us to the next step of realising a world of distributed power generation.

As an engineer, I don’t believe in organic evolution for technology. In other words, being reactive to technology changes. I believe in being proactive, evaluating what we have today, understanding the technology that is emerging and developing a path to embrace it. No one knows the future, but we can prepare for what we know is possible and evolve with the change instead of resisting it.

Disruptive technology has changed the world in the past and it will change the world in the future. This is one fact that is certain. What is not certain is how we react to it. Affordable storage is disruptive technology simply because it has the ability to change the status quo of power generation and distribution. 

So, what is so disruptive about the new Powerwall 2? Is it the cheapest battery solution on the market? Does it have new technology?

The Powerwall 2 is not the cheapest battery on the market and it doesn’t have any groundbreaking new technology, but what it has done is reduce the price of the first Powerwall and make it significantly cheaper.

This was done in two ways. First they double the capacity; the first Powerwall was seven kilowatt hours (kwh), now the Powerwall 2 is 14 kwh.

Secondly, there were significant hidden costs with the first Powerwall. It used a non-standard voltage 450 volts direct current for battery-based inverters, therefore a specialised inverter had to be made for the Powerwall. Only three companies made one that was compatible; SMA, Fronius and SolarEdge. Therefore, although the Powerwall was US$3 500 – which was very low relative to other Lithium-ion batteries – you could not use it with any of the established off-grid inverters on the market and therefore to implement it automatically came with an additional cost of US$4 000 or more.

The Powerwall 2 has a built-in inverter, which means at the estimated retail price of US$5 500 it is significantly lower than the first Powerwall. The equivalent Powerwall set-up to the Powerwall 2 would be US$11 000.

The changes don’t stop at the price. It is now indoor or output compatible; it supports direct current (DC) coupling or alternating current (AC) coupling; and it can be wall mounted or ground mounted. This new Powerwall has moved one step closer to be the perfect solution.

However, they are still lots of details that are not yet available. For instance, the DC voltage from this battery is still likely to be none standard at 450 volts (v), however the main reason for designing it this way was to allow it to provide a battery solution for grid-tie inverters where the Powerwall effectively extends the suns energy.

Off-grid inverters operate at DC 12V, 24V or 48V so those inverters will not be able to use the Powerwall or the Powerwall 2. However, the new Powerwall 2 supports AC coupling therefore it widens the list of compatible inverters to include the Studer Xtender inverter (Distributed by EnSmart Inc), the Schneider inverters, Growatt Hybrid inverter and a few others that supports AC Coupling.

So, the announcement of the new Powerwall 2 excites me as an engineer. It brings storage to the large grid-tie market while still allowing some off-grid inverter to include it into an existing system.

It is also encouraging to see the evolution of lithium-ion battery technology rapidly becoming more affordable. Musk is making sure that a future with distributed storage will happens sooner rather than later.

Therefore, we need to get past wondering if it is going to happen and start planning for when it happens and how we want to evolve with the technology. What we need to do is to facilitate distributed generation and storage while maintaining a network that can provide affordable electricity for those who cannot afford a solar system.

Jerry Franklin is managing director of EnSmart Inc. Franklin is an engineer, energy auditor, equipment tester, and energy solutions provider. He is also vice-president of the Barbados Renewable Energy Association. Email: jerryfranklin@ensmartinc.com


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