Expert analysis: The solar storage story


Tesla’s ability to generate excitement in energy storage is unprecedented. Do you see this translating into a win for the wider storage sector?

There has always been, economics aside, a large part of the population of the world that would be interested in, and have enthusiasm for, the idea of generating and storing their own electricity and relying on their own sources. That self-sufficiency desire, when paired with the accessible idea of Tesla’s product at a price point that starts to become quite compelling, is what you see now, with people moving forward on it.

Many of the cynics – myself included – still think that the economics don’t really seem to make sense as yet, particularly in the U.S. There is no real reason to install the Powerwall other than as a secure power backup supply. But then one of the analogies I’ve heard regarding this is that people don’t need televisions any longer, but they still own them, they still want them. The price point is fast moving to that consumer product, whereby people will buy the Powerwall not just for the economics, but because it is a desirable thing to have. This is interesting for the industry, and is not something that we necessarily see very often.

I actually think that the bigger opportunity long-term for Tesla will be outside the Powerwall, and will actually be the Powerpack, which is the commercial-scale product that hasn’t had anywhere near as much media attention.

What other storage products from the list most intrigue you?

The Sonnenbatterie product (#21 in pv magazine's Array Changing Technologies guide) is quite interesting – they’ve got a pretty leading position in Germany right now in terms of volume installed. They have quite a significant share of the German market. The company seems to be pushing longer life times and aggregated depths of discharge, which are both interesting things for the people that could potentially buy these batteries. These are key parameters that people want to see improved.

I am surprised that Sonnenbatterie is claiming 100% discharge – typically you would expect a battery that has been discharged to 100% of its depth would have quite a short lifetime. So if they’ve managed to move the depth discharge to 100% and increase the cycles then that is a significant improvement. But I am slightly cautious of that.

Overall, have you been impressed by the levels of innovation on display?

Generally speaking, it is important to point out how key innovation is at the moment in storage. We’ve been through a period of significant cost pressures, throughout the entire industry. Really we’ve moved into what most would call a commoditized market. Differentiating yourself within that environment – which comes down to innovation of products and innovation of business models – is becoming increasingly important. All of the storage offerings in the list are examples of interesting ways that companies are doing that, without picking out a specific one. Collectively, they are all important developments for the market.

Which products/approaches to technology do you feel might prove well-suited to the European solar market, and why?

All of the storage products included here are mostly aimed at residential systems. From an energy storage point of view, that’s certainly what’s going to make sense in Europe. If we are going to talk specifically about storage paired with solar, then the majority of those systems in Europe will be paired with residential homes. Whereas in many other parts of the world, you’re seeing storage paired with larger ground-mount systems and commercial buildings. All of the systems seem a very good fit for the European residential market in places like Germany, the U.K. and Italy.

In Europe, what kinds of incentives are there at residential and commercial scale to actually invest in energy storage?

Increasingly the business case for residential solar relies on self-consumption. Once the price of storage gets low enough, that will enable systems with a maximum amount of self-consumption. So I think storage is going to help residential solar to return to growth in Europe, as opposed to benefiting from growth.

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