My home Redflow ZBM2 energy system installation

Here is some information about my home energy storage installation.

  • 2 x 10kWh Redflow ZBM2 zinc-bromide hybrid flow batteries
  • Redflow ZCell BMS
  • 2 x 5000VA Victron Energy inverter/chargers
  • 10 kWp solar panel array in four strings using 2 x SMA 5000-TL inverters
  • Victron Energy CCGX configured for solar self-consumption (Hub-4)

The live system (with performance charts) can be viewed here: https://vrm.victronenergy.com/site/share/a2040765

The Victron Energy Hub-4 software in the Victron CCGX optimises the system for solar self-consumption. In the presence of excess solar generation, that energy is applied first to the home loads, the surplus to charging batteries, and the surplus beyond that to export to the grid (if connected).

CCGX Solar Generation Example

High solar output period

When there is less solar generation than the home loads require, those loads are supported by the solar energy that is available, which is then automatically augmented with battery energy. The grid is used as required to further augment home demands as required (either when the peak load exceeds the battery inverter capacity or when the batteries are fully depleted).

The system allows the configuration of an adjustable reserve percentage of the storage battery energy to be kept in the batteries in case of grid failure. It also allows the system to be charge up proactively from the grid in periods of low grid energy cost or ahead of incoming bad weather that might increase the chances of a grid energy failure.

The system automatically reverts to off-grid mode if the grid is unavailable, including recharging the batteries from solar energy to help support loads in the home for extended periods during such outages.

The performance of the system is very good. On a sunny week, most of our home electrical energy is provided by direct and indirect (battery time-shifted) energy. Of course in weather conditions offering reduced solar energy, more grid energy gets used.

Like a home rainwater tank system, this system acts as an electrical energy buffer, doing the best it can to avoid the use of grid energy, and prioritising the use of battery energy first.

hackett-vrm-week-sample

System performance example during a good solar week

The system works very well indeed – and flawlessly from the standpoint of my family, who see a house that ‘just works’ – even when the grid doesn’t. We all appreciate seeing the house operating well into most evenings on time-shifted solar energy harvested during the day.

Hackett Home Energy Installation

Two Redflow ZBM2 zinc-bromide hybrid flow batteries

Note that this system doesn’t use Redflow “ZCell” enclosures because it pre-dates the existence of those enclosures. It was one of the earliest production deployments of Redflow batteries in a residential context.

 

The ‘Apple vs Android’ inflection point for battery energy storage

Tesla’s unveiling of its new Powerwall 2 battery with a built-in AC inverter in October 2016 – along with some upcoming solar roof tile products – takes a leaf from the Apple playbook of vertical integration.

It’s the latest step on a corporate path (including the imminent merger with SolarCity) that moves Tesla closer to being a vertically integrated provider of energy solutions.

As with the Apple product ecosystem, this aims to establish Tesla as a single entry point for energy generation and storage systems in the home environment. Tesla has both the name and the resources to become a strong player in this realm.

Tesla’s vertical stance contrasts with the ‘horizontal’ orientation of the rest of the industry – a commercial ecosystem that offers choice at all layers of the energy storage system, using standardised interfaces to allow mix-and-match assembly of devices in the solution ‘stack’.

Tesla’s evolving approach stands to put it into direct opposition to former allies – both existing inverter/charger vendors that may be cut out of the Tesla solution set and experienced energy system installers, who may see the presence of hardware ‘handymen’ installing generic/entry-level solutions to often complex underlying energy management problems.

Implications for inverter/charger vendors – polarising innovation into distinct camps

Tesla’s Powerwall battery packs are high voltage devices that are not compatible with most industry battery inverter/chargers, which typically operate at 12, 24 or 48 volts DC.

The Powerwall 2 unveiling is an interesting day for inverter/charger vendors such as Solar Edge, manufacturer of the inverter of choice for the original Powerwall, which is no longer required with Powerwall 2. Likewise it is an interesting day for Fronius, which makes a three-phase inverter that supports support the first Powerwall version. The launch also impacts SMA, which recently released its SMA Sunny Boy Storage, a high voltage DC Tesla Powerwall-compatible battery inverter – that is now superfluous to requirements.

The bottom line for the emerging energy storage sector is that each time Tesla sells a Powerwall 2 with integrated AC inverter, an existing inverter/charger/energy control system vendor books one less sale.

As a result, this new approach from Tesla may tend to polarise the market into two camps over time – with a distinct sensibility developing that is akin to the long term battle of Apple vs Android in the smartphone market.

Implications for the industry – flexibility vs convenience

In the US, Tesla’s sales proposition adds US$1000 (and adds AU$1450 in Australia) to the Powerwall 2 purchase price to cover installation and associated ancillary hardware costs. One wonders whether this Tesla-determined margin for installers will be sufficient and sustainable for the provision of a professional-grade storage solution to the consumer.

This approach may also fail to accommodate specialised situations such as two-phase or three-phase installations, installations that require flexible interconnection, those that requite sophisticated energy flow management; or those that may require the integration of multiple DC or AC energy sources.

DC battery optimised applications

There are many commercial, industrial and telco environments where a 48-volt DC battery is more appropriate (and often, required), such as:

  • Data centres
  • Telco facilities such as mobile phone tower sites; and
  • High efficiency off-grid sites based on direct DC power systems, as in developing countries where pure DC-based energy systems are increasingly the norm.

In many cases, it can also be more efficient and effective to DC-couple solar panels to batteries using MPPT trackers than it is to use AC coupling, which requires separate inverters for solar and battery. This is especially relevant in pure off-grid or in grid-failure-backup scenarios, where DC coupled solar-to-battery charging can remove the need to have an AC generator available to ‘bootstrap’ the system in black-start scenarios.

(See this page for a comparison of AC coupling vs DC coupling approaches in the deployment of solar plus battery systems)

Challenges inherent with lithium-based batteries

While lithium-based batteries offer a core advantage – generally lower upfront cost – this energy storage chemistry presents substantial challenges that include:

Alternative battery technologies

Lithium based chemistries are the undisputed preference for transport applications (such as electric cars). Their high energy density and high peak power output makes them entirely appropriate in such use-cases.

However, a number of great alternatives to Lithium based chemistries exist (and can often be preferable) for stationary energy storage in home, commercial and industrial energy storage and delivery scenarios.

For example, Redflow ZCell batteries are a completely different energy storage approach that avoids the downsides of Lithium based batteries as noted above.

The ZBM2 storage module underlying the ZCell product also has other unique advantages, such as support for ‘Standby Power System’ (SPS) mode – a ‘virtual generator set’ operating mode.

The history of generator set deployment is littered with examples where backup generators simply don’t start up when called upon to do so.

In SPS mode, ZBM2 battery arrays can be fully charged and placed into indefinite hibernation. The full stored energy capacity held in the storage array can automatically be brought back online within 30 seconds (and yet with indefinite shelf life while on standby). This acts very much like a generator set but without the ongoing maintenance costs and also without the uncertainty around reliable startup that consistently challenges diesel generator sets.

The role of price in the purchase decision

Many industries demonstrate that price is not the only factor when consumers decide to buy. Whether choosing a product – such as a car, a plane ticket, clothing, Internet access plans, or even a seat at the theatre – price is just one decision factor.

If price was the sole determinant, we would all drive identically cheap cars, airplanes would have no business class seats and we would all wear identical beige clothes🙂

Safety factors such as the thermal runaway potential for many lithium-based battery chemistries are an example of a non-price consideration that can be extremely significant in many markets.

The way forward is win-win

There is plenty of room in what is now a rapidly expanding market for a wide variety of energy storage alternatives.

The bottom line is that Tesla’s presence in this market will drive increased interest in energy generation, storage and use. It will help to deliver further momentum to drive demand and adoption of energy storage systems in general.

It will also act as a catalyst for other energy generation and storage systems – using a variety of technologies and deployed a variety of physical scales – to each find their own appropriate ‘place in the sun’.

 

How State Governments can save money and drive the battery revolution

There is a great opportunity for Australian state governments to offer home battery storage incentives to consumers and to funding this incentive by repurposing existing, committed government expenditure. The mechanism I’m talking about is a voluntary trade-in offer, built around the residual payment stream for existing (and often very generous) solar Feed-In Tariffs (FITs).

These solar Feed-In Tariffs have already achieved their goal of kickstarting solar panel adoption in Australia. Indeed Australia is now among the world leaders in its per capita deployment of PV solar panels.

From a public policy point of view, continuing to pay solar Feed-In Tariffs well beyond the point where the underlying consumer investment in their solar installation has been fully paid off represents a substantial forward liability that does not deliver improved public good outcomes. However, state governments are clearly sensitive to the political risk of simply cancelling these long-running tariff schemes, some of which hold liabilities to as far as 2028.

However, Governments have an attractive way out of that problem, which serves both a public policy and industry development agenda while removing these long term liabilities from the public purse.

This involves inviting consumers to voluntarily trade in the residual life of their FIT in exchange for funding to buy a home battery energy storage system. This would have the dual benefit of eliminating a long-term forward liability for governments while kickstarting a home energy storage industry in Australia.

The remaining forward liability for a given customer can be readily estimated based on past subsidy payment patterns for that customer.

Past subsidy payment patterns are also likely to underestimate the remaining forward liability from the FIT schemes to governments. Each time a consumer reduces their home energy usage during daytime hours (through buying new and more energy-efficient appliances, installing automatic energy optimising control systems, and also through government-funded incentives such as this LED lighting replacement scheme), their future FIT payments from the government are set to rise still further in the future.

Accordingly, it seems likely that governments can likely save money overall by offering such a voluntary trade-in, even if the trade-in offer funds the entire capital cost of a home battery energy system. That up-front payment now could well be below the net present value of the (rising) forward liability of the FIT payments to the customer concerned.

Over the past year, Australia has emerged as a global battery proving ground because of its widespread deployment of PV solar panels and high electricity costs. Home batteries based on Lithium battery chemistries have been launched here by companies including Tesla, Enphase and Panasonic.

Redflow, an Australian company of which I’m Executive Chairman and a major investor, has recently launched its ZCell home battery, which is based on Redflow’s unique ZBM2 flow battery. This is a different kind of battery entirely. We believe it is far better suited to the long term demands and the daily ‘deep cycling’ required to store daytime excess solar energy generation and to let you use it to power your home at night.

The solar FIT buyout concept note here has been widely discussed in the Australian renewables sector and is reportedly under consideration by the Queensland Government. It has the virtue of re-using funds previously committed to kickstarting the PV solar panel sector to encourage the new home energy storage sector – with associated jobs and business growth.

Its important to appreciate that in many areas, the solar installation industry is now starting to saturate – with installers starting to struggle to find new growth areas in what has become a highly competitive pricing realm. The big opportunity for renewal in this industry is (now) the installation of battery energy storage systems in the same homes that have previously installed solar – but the high cost of battery systems at this early stage of the battery industry cycle is getting in the way. This voluntary FIT trade-in scheme could be just the growth catalyst the industry needs.

Just as with solar PV incentives, it will prove politically popular with citizens who increasingly regard home energy storage as a way to increase their energy independence and reduce electricity costs.

Widespread energy storage will also benefit far-sighted electricity companies by reducing demand during peak power periods and providing them with the possibility of buying home-stored energy as a ‘virtual’ on-demand power source rather than relying on fossil-fuelled driven peaking gas generators.

At a national level, widespread energy storage, both at the consumer and the grid level, will help Australia achieve its international carbon reduction commitments by time-shifting renewable energy so it can be used 24/7, not just when the wind is blowing or when the sun is shining.

Swapping solar Feed-In Tariffs for home battery installations is not just a win-win: It’s the gift that keeps on giving.

ZCell Launched

I’ve been working very hard with a wonderful team for quite some time now on launching the home-optimised version of the unique and very nifty Redflow ZBM2 battery.

Today we launched a new web site to announce that product (shipping mid year).

We’ve called it “ZCell”.

ZCell Logo

ZCell Logo

You can read all about it at http://www.zcell.com

For a variety of reasons (that you can read about at our FAQ section), we think this really is a better mousetrap. Its materially different (in better ways) to lead-acid and lithium based batteries.

We’ve been beavering away very busily here in Adelaide at Base64 on key aspects of taking this industrial-strength battery technology and reframing it as an easy to use, easy to install home energy storage system.

This technology is a huge passion of mine. I am quietly hopeful that we can make a positive difference to the world with it.

Why batteries will not cause mass defection from the grid

There’s a popular belief that the looming presence of batteries in people’s homes will lead to the widespread defection of those customers from the power grid.

In this view, living the dream means grid-independence where you harvest your own energy, one-finger salute the power companies and, when grid power fails for others in the street, your battery keeps the party going at your house.

While cutting the power cord sounds good in theory, in practice consumers gain many more advantages from staying connected to the grid.

Continue reading

New Net, New Grid – FiRe 2015

In October this year I had the pleasure of having an in depth conversation about how the new energy grid and the new Internet grid is starting to evolve – and about the interesting similarities and overlaps that are evolving between the two.

A key thrust of the conversation related to the way that scalable energy storage is the transformative physical component driving changes in how the energy grids of the world will work in the future.

That conversation was undertaken between myself and Larry Smarr.

Larry was the perfect partner for this conversation. He is someone I have had the pleasure to have known in various contexts for some years now, and (as you will see in the video), we share some similar views on the topics concerned. I had a great time riffing with him on these topics.

The video of this conversation is available for your viewing pleasure here.

It is a 15 minute video that was excerpted from a half hour session at the Future In Review conference held in Park City, Utah in October 2015.

The Future In Review conference is pretty amazing – I’ve been a part of it for many years. This year I was (of course) wearing my Redflow hat loudly and proudly at the event🙂

 

 

The New Power Game: Grid-scale batteries hit an inflection point

I’ve written a letter recently called “The New Power Game”

It looks at:

  • The rise of renewable electricity generation at grid scale
  • How grid scale renewables are starting to do the grid more harm than good
  • Why the addition of batteries at grid scale is the key to resolving that challenge
  • How this combination can replace (not merely augment) fossil-fuelled generators
  • Why new battery types – especially Flow Batteries – are ideally suited to this task

I found this very interesting to research and to write, and I hope that you find it just as interesting to read.

Please click on the link below to read ‘A New Power Game’.

The-New-Power-Game

This letter was written originally for subscribers to the Strategic News Service (SNS). It is posted here with their kind permission.