The Vale Energy System

About The Vale

The Vale is a 170 Acre farm in the NorthWest of Tasmania. It is located in a river valley in the shadow of Mount Roland.

Various crops are grown on the property along with the running of sheep and cattle. The property also features a large private runway.

We wanted to future-proof the property in terms of electrical energy self-sufficiency by building a large renewable energy system.

Here is what we built…

System Components

  • Three phase grid feed via a 500KVA transformer (configured for up to 200kWp export)
  • 100 Kilowatt Peak (kWp) ground-mounted solar array using 266 x LG 375W panels on Clenergy ground mount systems into 4 x 25kWp Fronius Symo AC Inverters
  • An additional 100kWp solar array (for a total of 200kWp) is currently under construction
  • Provision for future on-site generator
  • 144 kW / 180 KVA Victron Energy Inverter/Charger array (12 x Victron Quattro 48/15000)
  • 280 kWh of Flow Battery energy storage (28 x 10kWh Redflow ZBM2 zinc-bromide energy storage modules)
  • Victron Cerbo GX system controller interfaced to 3 x Redflow Battery Management System units
  • Underground sub-main distribution system servicing multiple houses, farm buildings and an aircraft hangar across the entire farm
  • Underground site-wide single-mode optical fibre network serving site-wide indoor and outdoor WiFi access points and networked access control and building management systems

A shout-out to DMS Energy in Spreyton, Tasmania. I designed the system with them, and they built it all extremely well. The installation looks great and it works brilliantly.

Here is a gallery of images from the energy system

Flow Batteries

The system stores surplus energy in Redflow Zinc-Bromide flow batteries. These are a product that I have had a lot to do with over a long period (including as an investor in the company and as the the architect of the Redflow Battery Management System).

These batteries have a lot of advantages, compared to using Lithium batteries, for stationary energy storage applications such as this one.

You can read more about them on the Redflow site and also in various other blog posts here.

System Performance and Future Plans

Tasmania is interesting as a solar power deployment area, because it has the distinction (due to being a long way south!) of being the best place in Australia for solar production in summer, and the worst place in the country for solar production in winter!

This was a key driver for the decision to deploy a relatively large solar array, with the aim of obtaining adequate overall performance in the winter months.

The large solar array is also a renewable transport fuel station!

We already run one Tesla Model S sedan, a Polaris ‘Ranger’ electric ATV, and an electric aircraft on the property.

Our plan is to progressively eliminate the use of diesel on the property entirely, by running electric 4WD vehicles, electric tractors, and electric excavators as they become available on the Australian market. The beauty of the large on-site solar array is that all of these vehicles can be charging directly from on-site solar generation when they are not being driven.

During this winter, we’ve observed that we typically manage to half-fill the battery array, and that it then lasts about half the night before grid energy is required.

That’s why we are now in the midst of doubling the size of the solar array. Once we have done so, we will have a system that (even in mid winter) can supply all of the on-site energy demands of the property on most days, without drawing any grid energy at all.

Of course, in summer, we’ll be exporting plenty of energy (and being paid to do so). Even with the relatively small feed-in tariff offered in Tasmania, the system generates a reasonable commercial return on the solar array investment in non-winter months.

Here are some (summer time) screen shots from the on-site control system and from the outstanding Victron VRM site data logging portal.

On the image from the on-site Cerbo GX controller, you can see a point in time where the solar array was producing more than 90W, the battery array was mostly full and starting to roll back its charging rate, and plenty of that solar energy was also being exported to the grid.

The ‘System Overview’ and ‘Consumption’ charts show the outcome of all that sunshine…with the battery ending the day pretty much full, the site ran all night on ‘time shifted sunshine’ and started the following day half full, ready to be filled up once more.

We exported plenty of green energy to our neighbours and we used practically no inward grid energy at all.

Once we have doubled up the solar array size, we are looking forward to achieving a similar outcome on most winter days, not just during summer, along with exporting even more surplus green energy into the grid.

Once we have transitioned all the on-site vehicles to electric, our total export energy will diminish somewhat, but it will be more than offset by a $0.00 diesel fuel bill (and by zero CO2 and Diesel particulate emission from our on-site activities).

On-site Energy Efficiency

One thing that matters a great deal is to do the best you can in terms of energy consumption, not just energy generation and storage. To state the obvious: The less energy you need to use, the longer your battery lasts overnight.

All the houses on the farm are heated/cooled using heat pumps.

This is the most efficient way to do it, by far. It is often poorly understood just how much more efficient a heat pump is, compared to any other way to cool or heat something.

That’s simply because a heap pump doesn’t create the heat – rather, it moves heat energy in the outside environment into the house (or vice versa, to cool it). Typical values for the Coefficient of Performance (COP) – the ‘multiplier effect’ between kilowatts to run a heat pump and kilowatts of heat energy that can be moved – are of the order of 3-4 times. That literally means that 3-4 times as many kilowatts of heating or cooling are created than the number of kilowatts of energy put into the device to do it. By contrast, heating using an electrical ‘element’ has a COP of 1, meaning there is literally no multiplier effect at all.

Because we’re in Tasmania, and it does get cold in winter, we have put in a wonderful indulgence in the form of a Spa pool. These obviously need a fair bit of energy to keep the pool water hot, and we have done two things to minimise that energy draw.

First, we have used a Spa heat pump to do the hot water heating, which accesses that fantastic multiplier effect mentioned above. It means we are heating the water by just moving heat energy out of the surrounding air and into that water.

Second, we have installed an optional monitoring and control device so we can access the Spa and remotely control it. We can turn the heating off when we are leaving home, and we can then remotely turn the heating back on when we are heading back, so it is nice and hot when we arrive.

We have a third heat pump at our home, the one that heats our hot water. We are using a Sanden Heat Pump based hot water system that (also) performs really well.

On-site Energy Monitoring and Control

The key to optimising energy usage is to be able to actually measure it.

The Victron Energy Cerbo GX at the heart of the energy system monitors all aspects of our renewable power plant in detail (and uploads them for easy review to the no-extra-cost Victron Energy VRM portal). This gives us fantastic (and super detailed) visibility into energy generation, storage, and consumption on site.

However, we have a lot of separate buildings on the farm, and the key to understanding and optimising energy draw is to get deeper insight into which buildings are using energy and when.

To that end, we have installed many Carlo Gavazzi EM24 ethernet interfaced energy meters all around the site-wide underground power network. At each delivery point into a building, there is an ethernet-attached meter installed, so that energy usage can be narrowed down to each of these buildings with ease.

I am currently working on the design of an appropriate monitoring system that will draw this data in and use it to provide me with detailed analytics of where our energy is going on a per-building basis (and when!).

In terms of control we have deployed KNX based sensor and control devices in a variety of places around the property, and we plan to deploy much more of it. Over time, we’ll be able to dynamically control and optimise energy consumption in a variety of useful ways.

KNX is a whole separate story, but – in brief – its an extremely good way to implement building automation using a 30+ year old standardised protocol with full backwards compatibility for older devices and with support from over 500 hardware manufacturers. It allows for the successful deployment of totally ‘mix and match’ multi-vendor collection of the best devices for each desired building automation monitoring or control task.

We are continuing to learn as we go.

With the upcoming enhancements in site monitoring and control, we expect to deepen our understanding of where energy is being used, to (in turn) allow us to further optimise that usage, using techniques as simple as moving various high energy demands to run ‘under the solar curve’ wherever possible. These are the times when on-site energy usage is essentially ‘free’ (avoiding the ‘energy round trip’ via the battery, and leaving more battery capacity for energy demands that cannot be time-shifted overnight)

Summary

Overall, this system is performing extremely well, and we are extremely pleased with it.

When we have added even more solar, it will do even better.

The #1 tip – even in Tasmania – is clear: Just Add More Solar ūüôā

The other big tip is to move your transport energy usage to electric.

The more electric vehicles we can deploy here over time (farm machinery as well as conventional cars), the better.

We’ll charge them (in the main) directly ‘under the solar curve’ and achieve a huge win-win in terms of both energy usage and carbon intensity.

As we keep learning and keep improving the monitoring and control systems… it will only get better from here.

The Redflow Gen3 ZBM

The Redflow Zinc-Bromine Module (ZBM) is the smallest commercially available hybrid zinc-bromine flow battery in the world. The size of these 10kWh energy storage modules means they can be deployed in applications, such as telco tower sites, that were previously impossible to address with flow batteries, yet they can also scale to grid-level energy storage.

The Redflow ZBM is a convention-breaking energy storage machine. It can be thought of as a miniature, reversible, zinc electroplating machine made largely of recyclable plastic. The innovative Redflow battery design uses abundant and relatively cheap minerals in its electrolyte formulation. These attributes gives the product strong environmental credentials. 

I recently spent some time at Redflow’s Brisbane headquarters taking a close look at the new Redflow Gen3 energy storage module. It is impressive to see just how far the Gen3 project has progressed in recent months and to appreciate the level of innovation it embodies.

Redflow has developed and optimised the design of its Gen3 battery in various stages during  the past five years, incorporating knowledge and optimisations based on field deployment of the Gen2.5 product. The Gen3 battery utilises the advanced manufacturing capability developed by the company in its own dedicated factory and delivers a streamlined product designed for reliable and high volume production.

The Gen3 ZBM is slightly smaller, and yet delivers the same baseline performance specifications as the Gen2.5 module. Gen3 is designed to be an easy, drop-in replacement for the previous model in any customer application.

Redflow initiated Gen3 customer trials at the end of 2020 and also undertook further lab testing of key components and complete new Gen3 batteries. This has led to further design advances in Gen3 flow distribution, management of shunt currents and software optimisation. The current expectation is that Gen3 will be introduced into production around the end of 2021.

This is what a Redflow Gen3 ZBM looks like:

Redflow Gen3 ZBM

It is time to take a look under the hood… and the more you look, the more improvements become evident.

This is a photo of some Gen2.5 batteries, for comparison, sitting beside a Gen3 battery undergoing testing at Redflow:

Gen3 battery beside some Gen2.5 modules

There are many improvements in Gen3, all designed to reduce parts count and cost while also making the product easier to manufacture.

Single Stack vs Dual Stacks

The key Gen3 improvements are related to the ‚Äúheart” the device, the electrode stack.

This unique battery stack design, materials set and manufacturing system are where the majority of the Intellectual Property, Patents and Know-How developed by Redflow over the past 10 years resides. The new Gen3 stack represents a major step forward for the company in all of these respects.

This new product implements a single 10kWh stack at the top of the Gen3, replacing a pair of 5kWh stacks on the Gen2.5 model. Having just one stack instead of two delivers an obvious long-term reliability benefit.

That single stack also lowers production cost and reduces complexity in physical, chemical, and electrical terms. Redflow has also revised the internal construction of the new stack, including the fluid flow paths and the stack surface itself, for simpler and faster manufacture.

Gen3 Stack electrode plate layers ready for final assembly

This single stack design eliminates the need to wire the two stacks together in parallel with an adaptor plate on the front of the stack, reducing parts count and complexity.

Moving to one stack also removes the requirement to bind the two stacks tightly together with large metal plates and long bolts. The Gen2.5 requires these relatively costly structures to maintain a consistent electrolyte fluid seal and to manage consistent electrolyte flow across both stacks. In Gen3, none of that is needed

The single new stack is simply strapped on to the top of the battery tanks, making it easier to replace the stack in the future, if required.

Because the stack is also a major cost item in the ZBM bill of materials and is also a critical path item in manufacturing time, the single stack delivers obvious and profound implications in terms of increased peak factory production rate and decreased overall production cost.

New Electronics Module (MMS)

The Module Management System (MMS) – the electronics box on the front of the battery stack – contains power-handling and control electronics which are run by an on-board device management computer.

The Gen3 MMS has been totally redesigned, delivering both short and long-term benefits.

The Gen2.5 battery MMS contains several separate circuit boards, due to more than a decade of incremental development. Gen3 puts them all on a single, redesigned, higher performance board.

The Gen3 battery MMS also has battery terminals on the front of the unit, rather than ‚Äėbehind‚Äô the MMS, which makes electrical interfacing a lot easier.

The Gen3 design eliminates the separate ‚ÄúEnergy Extraction Device‚ÄĚ (EED) sold with Gen2.5 batteries by building that functionality into the MMS as a software-controlled element.

The new MMS costs much less to make and is far more powerful in terms of CPU and I/O capability.

Advanced current flow management and software-driven bidirectional DC/DC conversion circuitry allows for the development of improved MMS firmware to deliver new software-driven current control and voltage control features, along with other planned improvements. These will be rolled out to customers through in-field software updates via the Redflow Battery Management System (BMS).

Other improvements in the new MMS Include the use of solid-state circuit-switching hardware based on Field-Effect Transistors (FETs) to connect, disconnect and mediate energy flow into each ZBM, versus the use of three physical ‚ÄėContactors‚Äô inside the Gen2.5 MMS. This eliminates some expensive moving parts from the MMS by replacing them with devices that are not only faster but that have an essentially unlimited cycle life in this application.

Redesigned electrolyte tanks, pumps, and cooling structure

The ZBM has two electrolyte tanks, each with its own pump. The Gen2.5 uses a nested, ‚Äėtank within a tank‚ÄĚ arrangement that, while elegant, is quite complex and expensive to make. Gen2.5 tanks are also constructed with many sharp corners and a complex side-wall design, making high volume manufacturing even more challenging.

The new Gen3 tanks are quite different. This is a picture of the new tanks with pumps without any other parts installed. You can see that there is a new plastic formulation and that they feature distinctly rounded corners:

tank

This is all designed to optimise the tank for volume production. This design is easier to build and has an increased tolerance for variation between tanks during the manufacturing process. The new tanks are also arranged as a simple left-right pair ‚Äď much simpler than  the Gen2.5 nested tank structure, further improving ease of assembly.

The pumps have also changed. For historical reasons, the Gen2.5 pumps are actually 140 volt DC pumps that require a custom-designed voltage uplift circuit inside the MMS to drive them. The Gen3 pumps are 24 Volt DC pumps that can be more easily and efficiently driven from the MMS.

As part of the new Gen3 design, Redflow is also introducing a new cooling system using a new set of Filtering Polymeric Fibrous materials which will improve battery performance.

All up, the new tank cooling system and pump set represent a major improvement, designed, like the rest of Gen3, for repeatable high-volume manufacture at a lower production cost.

Purpose-built electrolyte ‚Äėbund‚Äô

In many markets, energy storage devices that use fluid electrolyte in field deployments need to include a ‚Äėbund‚Äô – somewhere to catch and hold electrolyte fluid in the unlikely event of a fluid leak.

For the Gen3 battery Redflow has a new purpose-built bund. This is the plastic enclosure extending to about halfway up the battery on all sides, that is visible in the lab test photo above.

The intention is to ship Gen3 batteries with this bund included, saving installers the need to arrange and install a separate bund.

Gen3 Summary: Greater reliability, lower cost, faster production

The Gen3 module marks a major transition for Redflow.

Gen3 is designed for volume manufacture, with a design emphasis on fewer parts, greater ease of manufacture, and more compatibility with automated production techniques. By intent, this all leads to a lower production cost and greater long-term reliability.

These improvements benefit both Redflow and its customers as the company moves to ramp production volumes to meet the rapidly expanding global demand for scalable, sustainable and reliable energy storage.

Flying On Electric Avenue

I am fortunate to own the first electric self-launch glider to fly under Australian skies. It is a Pipistrel Taurus Electro G2.

A few months ago, I wrote a story that explained the background and my journey to owning and flying this impressive little aircraft. The story was published in the Gliding Federation of Australia’s Gliding Australia magazine.

You can read the article here .

Alternatively here is the same article as a PDF file:

Electric Avenue – Taurus Electro G2

I’m posting these links as a precursor/background to a story I will write soon about three wonderful days of flying this aircraft from our airstrip in Tasmania.

The Role of Flow Batteries in Dispatchable Renewable Energy Grids

At the Australian Energy Storage conference held in Adelaide, South Australia on May 23-24 2018, I delivered this keynote address about the role of flow batteries and other energy storage technologies in the context of building an energy grid with renewable energy in the majority and with “Baseload” generation on the wane.

The core thematic question I posed was this: Is a future grid with large amounts of renewable energy storage necessarily using Lithium-Ion (or other, otherwise conventional) battery systems for the majority of that large scale energy storage – or are there better ways?

A specific underlying aspect of that conversation is about environmental impact – around the notion of ‘environmentally friendly’ energy generation and storage being a notion that must factor in the ultimate environmental impact for each storage technology and not just its up-front cost.

The video below is a recording of my address synchronised to the slide deck that I used.

The standalone slide deck is also available here: Hackett-Keynote-Redflow-AES2018

How Redflow Batteries Work

I often get asked to explain how Redflow ZBM2 flow batteries work – compared to conventional batteries – and how batteries fit into your life in a home situation.

An interview I did a while back with the delightful Robert Llewellyn explains those things.

So… If that’s a subject you’re curious about, and you’d like to spend 15 minutes learning the answers… this¬†Fully Charged show about Redflow ZBM2 flow batteries¬†explains it !

 

The Base64 Redflow Energy System

Updated Feb 2019: System now operating at full battery capacity and with increased solar array size

The Base64 energy system has been a fantastic learning experience for us in general and me in particular.

The system is¬†built around a large Redflow ZBM2 battery array. We call these configurations an “LSB” (Large Scale Battery). It is charged with solar energy harvested from a large solar array (most of which is ‘floating’ above the staff carpark).

We deployed it first some time ago now, prior to having got so deeply experienced with using Victron Energy inverter/charger systems. At the time we (Base64) purchased a big custom industrial AC inverter that didn’t come with any sort of monitoring or logging system and no control system to drive it to interact properly with on-site solar.

All of the necessary energy system control, management and data logging technology comes ‘out of the box’ with the Victron Energy CCGX controller unit in a Victron installation, ¬†so I imagined ‘everyone’ provided such things. Well, I was wrong about that.

The big industrial unit we bought came with nothing but a MODBUS programming manual and created a lot of head-scratching along the lines of… ‘now what?’. For some reason industrial scale systems are in the dark ages in terms of the stuff that Victron Energy have ‘nailed’ for the residential/SOHO battery market – they supply great, easy to use, easy to understand, effective and powerful out-of-the-box energy system control software and hardware (entered around their CCGX/Venus system). It also comes with an excellent (no extra cost) web-accessible portal for remote data logging, analysis and remote site system control.

Meantime, we were exercising our large battery ‘manually’ – charging and discharging it happily on a timed basis to prove it worked – but we were unable to run it in a manner that properly integrated it with the building energy use, for the lack of that control system in the inverter we had at the time. We didn’t want to write one from scratch just for us – that’d be a bit mad. We also didn’t want to pay someone else thousands of dollars to set up a third party control system and make it work – a major consulting project – just to do what the Victron Energy CCGX does on a plug-and-play basis at very low cost.

In parallel, and importantly – it also took ages to get substantial on-site solar operating at Base64 – and there wasn’t much point in driving the LSB in production until we did have a decent amount of on-site solar to sustainably charge it with.

To the latter point – we are in an massively renovated and reworked heritage listed building and I was unable to get permission to mount solar on the massive north-facing roof of the main building.

Instead we commissioned a rather innovative mounting system that has (at last) let us complete the installation of a 50kWp solar array that literally ‘floats’ above our staff car park on four big mount poles supporting what we call ‘trees’ – suspended metal arrays holding the solar panels up.

That system was commissioned and imported from a company called P2P Perpetual Power in California to suit our site. There are lower cost systems – but (by comparison) they’re ugly. We wanted it to be beautiful, as well as functional – because Base64 in all other respects is…both of those things.

It was worth the wait.

The result is (in my humble opinion) quite spectacular.

Including that ‘floating’ 50kWp array, we have a total of 99kWp of solar on the site, though some of the rest of it is on ‘non-optimal’ roof directions, and so on a good day what we see around 80kW generated at peak in the high (solar) season.

That said, the advantage of some other parts of the solar system being on east and west facing rooftops is that our solar generation curve runs for more hours of the day. We get power made from earlier in the day (from the eastern array) and later into the evening (from the western one) – and that’s quite helpful in terms of providing a solar energy generation offset to local demand patterns.

In parallel, we pulled the LSB apart and rebuilt it using Victron Energy products and control systems, so that we could get a fantastic operational result and have optimal use of the solar energy to drive the building, charge the batteries, and support the building load at night – the very same stuff we do in houses with our batteries, just on a bigger scale – without facing a one-off software development exercise for the old proprietary inverter system we had been using.

Swapping the Victron Energy gear in has turned out cheaper and far better than the bespoke software exercise would have ever been. It has also created a signature example of a large scale Victron Energy deployment running a decently sized multiple building site. I hope that this, in turn, may inspire more of the global Victron Energy installation community to consider the use Redflow battery technology at this sort of scale.

The battery array is built with 45 x ZBM2 = 450kWh of Redflow energy storage.

We have 72kWp of Victron inverters installed right into the container as well. We could have gone larger (in terms of peak inverter power), but these have been ‘right-sized’ to the building demand at Base64, with summer peaks normally around 60kW (75-80kW worst case) and typical draw around the 30-40kW level when the building complex is in daytime operation.

It is all linked to that 99kW distributed solar array using via multiple Fronius AC solar inverters.

I’m thrilled with how well the system is working – its a monument to all of our Redflow BMS development work that the whole thing – at this scale – really is ‘plug and play’ with the Victron CCGX energy system controller and the associated inverter/charger equipment.

It is very satisfying to run an office in the middle of a major city that typically uses very little grid energy, that is resilient to grid faults, and that even still exports solar energy to the grid as well.

A subsequent step will be to interface with a grid energy ‘virtual power plant’ operator in the future, so that we can sell battery energy back to the grid during times of high grid demand.

Every battery system on an energy grid has the potential to also become a programmable grid-supporting energy source during peak load periods. The missing links are software, regulation, and attitude – with the software part being the easiest of the three.

We can easily set up to proactively control over when the battery charges and discharges in response to, for instance, wholesale market price. The Victron control system makes that easy. ¬†What need to give that project legs is an innovative retailer who will work with us on that and a small amount of software ‘glue’ to make it happen on our local site.

Here is a little gallery of photos of the system that we’ve installed – click through them for a little more information about the system.

 

 

Redflow ZBM2 deployment at Bosco Printed Circuits

A case study in complex energy system optimisation

Bosco Printed Circuits is the largest maker of Printed Circuit Boards (PCB’s) in South Africa. The production line at Bosco needs a lot of energy. The direct and indirect consequences of losing energy supply to the line are substantial.

Johannesburg, where Bosco are based, has significant issues with energy supply – both in terms of reliability and also (as a consequence) in terms of energy cost.

Like most businesses, Bosco already had an extensive solar array installation, which certainly helps with the economics of energy supply. The solar array is not sufficiently effective, is isolation, to address the complex challenges for the business in terms of supply cost and supply security.

Energy supply to Bosco from the grid utility is time-of-day based. The energy supply cost is very high during distinct morning and evening peak periods, to discourage energy use in those times. These peak time bands are periods of high energy requirement for Bosco. The are the times when the potential for grid failure is greatest and are also the periods when the consequences of grid failure for Bosco are the most severe.

Of course, these times (early morning, late afternoon) are also exactly the periods when the solar arrays can’t help, as they are outside of the solar peak generation periods.

Grid outages are expensive for Bosco. Not only do they result in lost productivity, but they also have further economic consequences in terms of partially produced PCB’s having to be scrapped when the production machines are halted without warning.

The Challenge

Bosco had a variety of business aims and objectives across their daily operating cycle that their energy system had to address:

  • To ride over transient periods of grid loss seamlessly using battery energy
  • To support the operation of the production line for an extended period (hours, not merely minutes) in the face of longer periods of grid outage, so that the company can keep working, using battery energy augmented with any available solar energy, for as long as possible.
  • In cases of a very extended grid outage (several hours), to allow the production line to be closed down with plenty of warning (at least an hour) from the point at which the shutdown decision is made.
  • To time-shift energy obtained from the low cost overnight off-peak period into the morning peak period (0600-0800), prioritising battery energy usage at this time in order to minimise the use of very expensive grid energy.
  • To also minimise afternoon peak-period grid usage by again prioritising the use of battery energy in this second daily period
  • To use the residual battery energy, harvested from overnight off-peak charging and from any excess of daytime solar power, to supply the background energy needs of the building into the evening.
  • To recharge the battery array again using off-peak power from midnight to 6am ready to commence the next daily cycle.

This need set required a battery energy system capable of consistent hard work and capable of daily 100% energy discharge, working in a hot environment, and without loss of output capacity over time.

The Solution

The solution uses 14 x Redflow ZBM2 batteries (140kWh) interfaced to a large array of Victron Energy inverter/chargers and a large solar array.

The system orchestrates this complex daily cycle of energy optimisation using the Victron CCGX and the Redflow BMS, to achieve the aims and objectives noted above.

Here’s a typical day in the life of this system, in terms of the sources of energy to run the plant:

Bosco Daily Cycle Example

Bosco Printed Circuits Energy Consumption

You can see the periods where the battery system energy (blue) is prioritised in order to minimise the use of grid energy during peak times. You can see the battery being fully utilised to supply energy during the afternoon and evening as the solar consumption falls away, and you can see the system recharging using off-peak energy again from midnight, ready for the following day.

You can use this Bosco Printed Circuits VRM Portal Link to see the live system running.

Bosco ZBM storage array

Bosco ZBM storage array (12 batteries shown – a further 2 were added later)

 

 

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 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‚Äôs unveiling of its new Powerwall 2 battery with a built-in AC inverter in October 2016 ‚Äď 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‚Äôs vertical stance contrasts with the ‚Äėhorizontal‚Äô orientation of the rest of the industry ‚Äď 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 ‚Äėstack‚Äô.

Tesla’s evolving approach stands to put it into¬†direct opposition to former allies ‚Äď 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 ‚Äėhandymen‚Äô installing¬†generic/entry-level¬†solutions to often complex underlying energy management problems.

Implications for inverter/charger vendors ‚Äď 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 Рthat 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 ‚Ästwith a¬†distinct sensibility¬†developing that is akin¬†to the long term battle of Apple vs Android in the smartphone market.

Implications for the industry ‚Äď 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 ‚Äď generally lower upfront cost ‚Äď 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 ūüôā

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’.

 

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.