A plan B for energy storage in your home

Solar Business Services

timthumb.php

Last week we wrote a popular piece on some of the intricacies of solar storage and how ev’s and home energy storage are similar, but different. As if to drive the point home, the day after we went to press US solar leviathan Solar City announced plans for microgrids using Tesla batteries. Local fast charger company Tritium also announced a huge deal with US based ChargePoint to export their ev fast chargers to the US.

Whilst I am in agreement with the many others who believe that ev’s and home energy storage will be massive in the very near future, I also see two other emerging possibilities that will have some type of impact on the growth of the crucial battery market. How much is unclear.

EV’s – capacity versus infrastructure versus mobile

Being an EV owner like all others I suffer from the constant (slightly weird and obsessive and creepy) dream that I have loads more battery capacity than I actually do. Sometimes I literally wake up in the middle of the night after dreaming I can ride 500km or more, and then realise I have to settle  down and accept my 200km or so range.

The promise of higher power density batteries is very strong and Zero’s own Chief Technology Office gave a very revealing and fascinating interview recently on the subject staying “there are chemistries being developed right now that are quadrupling energy density“.  That’s cool but Murphy is a bitch and these things inevitably take time so for the next year or so we are likely to be where we are right now, with smaller incremental changes. There will always be a limit too, whether its real estate availability (on bikes) or weight that will restrict how much we can carry around.

Enter the fast charger.

The theory is that with enough fast chargers, the onboard capacity doesn’t matter so much because you can top up in almost the same time as a petrol refill. Tesla are leading this strategy and their owners enjoy a staggering level of accessibility and support to this infrastructure, but I seem to have misplaced my $150 grand to have the privilege of owning one and their charging stations work EXCLUSIVELY on their vehicles. (annoying, I think it’s the wrong strategy but can’t say I blame them).

So for the rest us mere ev mortals, we are reliant on public charging stations, which are about as common in Australia as pro-solar support from Government. And to make it even worse the world is in the midst of an ugly and time wasting stoush about what ev charging system is best (DC/CHaDEMO or AC/J series). No one can agree across the world so everyone is doing their own thing. DC is more efficient but things can get a little sketchy at 300-500VDC (roof isolators anyone?) and there also a range of preferences for different battery voltages, so you may or may not be able to get a  top up on some of the chargers anyway. The other issue is all the dedicated infrastructure cost – in one local case it was around $40,000 to get the power to where a fast charger would be located.

In Australia we have mostly J series which in simple terms limits your ability to recharge to the capacity of your on board charger. Today, this is pretty dumb because 25kW chargers are huge and heavy and not really designed for automotive integration, let alone fitting in my saddle bags. There are work-around’s (like Electric Terry’s bike in the photo!) , but it’s a pain right now.

HOWEVER, miniaturization is coming at a rate of knots. When (not if) chargers are smaller, more modular, lighter and more flexible this problem starts to go away. Users can squeeze them in as aftermarket solution. Suddenly, the need for complex dedicated infrastructure start’s to ebb because all that’s needed is a 3 phase outlet delivering 50A – which costs around $720 for the outlet. Of course, the power still needs to be delivered, but 3 phase is already widely in use.

If we could leverage this as a lower cost solution to the infrastructure, then access to recharging would be far more common. Each user would then invest in the desirable charging capacity and take it with them, anywhere they want to go on their car or bike. With 25kW available, I could get 100km range top up in less than 15 minutes for example, which is pretty respectable.  On a Zero the battery is worth around 7kg per kWh so there comes a point at which for both bikes and cars, electronics miniaturisation will beat this and then – it may make sense to add chargers instead of batteries.

So, miniaturized chargers could effectively take away some of the battery market.

Hot water

Then there is the issue of home energy storage of course, and when you look at what uses energy in the home hot water is huge. Gas was cheaper but that’s changing rapidly. I was invited to pretend to be an expert recently at a “Sustainability Speed Date” and I found myself telling punter after punter the same thing. “Yep, gas is very likely to go up in price significantly” and “Yep, you’ll get virtually nothing for the solar energy you produce during the day if you are out” and “Yep, storage is getting very close but you’ll need $10k or so today” .

The inevitable conclusion of course is to use a heat pump and offset the energy consumption with a timer and solar PV system or, to utilise a standard electric tank with a “solar diverter”, which sheds excess solar energy directly to a heater element.

There are several companies around offering diversion products which look ok, but I have to ask the questions – why aren’t more people offering these products, why does a little computer with some relays and stuff cost a thousand bucks, why do they all lack a bit of finesse and why do they all seem to come from the UK?

What am I missing here?

I’ve read a couple of great stories and numerous installers and wholesalers selling them but this product niche doesn’t seem to be filled yet. I suspect this will change pretty quickly and the economics look pretty sound.

So, energy diverters could also take away some of the battery market.

Ultimately, battery storage will grow and the alternatives aren’t quite there yet, but like all markets there will more than likely be a nifty Plan B.

Source: Solar Business Services. Reproduced with permission.

Comments

8 responses to “A plan B for energy storage in your home”

  1. barrie harrop Avatar
    barrie harrop

    watch Tesla for home storage towards end of April .

  2. disqus_3PLIicDhUu Avatar
    disqus_3PLIicDhUu

    “Today, this is pretty dumb because 25kW chargers are huge”
    Not necessarily so, chameleon charging reduces the need for large heavy inductors, by cleverly, using the motor as the inductor, for a small 43kW faster charger that can be plugged into a standard 63A a.c. outlet.
    http://evmeerkat.com/cz/renault-zoe-ev-and-its-chameleon-charger-bye-bye-plug-at-home-connector-good-plan/
    Here’s another small 25/35kW charger.
    http://emotorwerks.com/products/online-store/product/show/75-quickcharge-25000-hv-a-25kw-pfc-charger-for-higher-voltage-batteries

    As for hot water what a waste diverting high quality energy, pv electrical and dumping it into hot water, better to control it’s use and store it, in batteries.

  3. Craig Allen Avatar
    Craig Allen

    Diversion units that include an element that can be plumbed onto an existing hot water system are needed for households that have them.

  4. Kevin Brown Avatar
    Kevin Brown

    If solar households diverted their excess output into their hot water system and adopted off-peak hot water heating the energy markets “duck curve” consumption problem could be substantially flattened. Why aren’t our energy suppliers promoting this? Because they make greater profits if they build more “poles and wires” and the last thing they want to do is reduce peak loads.

  5. Raahul Kumar Avatar

    I would hope for an alternative to batteries, because hot water, fuel cells, and flywheels all seem to be much better alternatives than batteries. On the grounds of cost, working life, and toxicity the battery has had its day.

    1. wideEyedPupil Avatar
      wideEyedPupil

      you wanna ride a motor bike with flywheel storage then be my guest. haha

      1. Raahul Kumar Avatar

        Vehicles of all types will be using flywheels instead of batteries. Hybrids are the obvious first application.

        http://www.theguardian.com/science/blog/2014/jan/27/flywheel-hybrid-flybrid

        ” Can flywheel technology drive out the battery from car hybrids?
        Batteries are energy intensive to make and problematic to dispose of. Flywheel technology, known as Kers in the Formula One world, could be a solution”

        An Assessment of Flywheel High Power Energy Storage Technology for Hybrid Vehicles

        http://www.compositesworld.com/cdn/cms/ORNL%20Flywheel%20Assessment%20for%20Hybrid%20Vehicles%202011.pdf

        The reason why:

        Kinetic energy is transformed into electrical energy in a motor/generator

        Then the electrical energy is transformed into chemical energy as the battery charges up Later the battery discharges, transforming chemical into electrical energy

        Finally, the electrical energy passes into the motor/generator acting
        as a motor and is transformed once more into kinetic energy

        The four energy transformations undermine the overall level of efficiency.

        1. wideEyedPupil Avatar
          wideEyedPupil

          Not instead of batteries, in addition maybe. Energy density for flywheels is low, while power density is higher than batteries.

          Like I said good luck with a flywheel on a motorbike, gyroscopic forces being what they are a flywheel of any significant power and energy density would become a ride issue.

Get up to 3 quotes from pre-vetted solar (and battery) installers.