Battery storage: What am I buying, apples or oranges? | RenewEconomy

Battery storage: What am I buying, apples or oranges?

Print Friendly, PDF & Email

There’s plenty of sizzle but what exactly is the sausage?

Print Friendly, PDF & Email

There’s plenty of sizzle but what exactly is the sausage?


With the explosion of domestic battery storage products on offer, early adopters are generally savvy with the technical aspects of this new technology and know what questions to ask.

But Ma and Pa Kettle, who will make up the clear majority of battery storage owners in the future, have no simple means of comparing product offers and can’t be assured that their investment will meet their expectations.

This week this writer is in Madrid, Spain, on behalf of Australia, helping form the international umbrella standard on Electrical Energy Storage Systems, the standard that will endeavour to cover all forms of electrical energy storage whether it is electro-chemical, hydro or any other method.

One of the significant points for discussion, and one which has crept up like a Vietcong guerilla, is the means by which energy storage devices, most specifically those with degrading accumulation like chemical batteries are “rated”.

Currently, early adopters are relying on the “sizzle” put forth by the storage suppliers and in many cases availing themselves of the excellent reference site put together by Finn Peacock from Solar Quotes.

Like the rush of domestic PV installations which eager or crooked sales people over sold, leaving the installer to take the flak from dissatisfied customers, battery storage risks the same reputation in the absence of a uniform rating system for particularly domestic storage.

It’s all very well to place a nameplate that says your battery storage system is rated at say 10 kilowatt hours, but what does that mean to a person spending around $10000.00, what is the customer’s reasonable expectation and how can this be readily defined and policed?

If we use the Tesla Powerwall 2 as an example, their warranty has settled on the headline capacity of 13.5 kWh. The warranty states that the units will continue to operate at a minimum 70% of this initial capacity after ten years of daily cycling. It must be assumed that the system will continue to operate after that time but at an undefined capacity.

It is reasonable for the suppliers to limit warrantied values and performance to a period that reasonably reflects the purchase cost. In the case of battery storage, 10 years seems more than a reasonable period where the customer may take recourse on the supplier, should the product fail to meet the customers well informed expectations.

These expectations are the issue; how do manufacturers clearly articulate the performance and longevity characteristics of battery storage in a way that can be simply compared with the competition?

It has been suggested that the correct way of rating the storage of a battery storage system is to under state and over deliver. In this case, the Tesla would have a rating of 13.5 x 70%, so should therefore be sold as a 9.5kWh system, with a uniform industry reference period of ten years.

For solar PV modules, this works because the modules are uniform in their componentry, construction and usage, battery storage is a totally different story:; chemistry, cycling and environment all vary greatly, so to simplify the selection process for consumers is a great challenge.

Currently most electrical appliances, and motor vehicles have a simplified rating system which is a score with a minor amount of technical clarification.

This is simple enough for ordinary consumer to readily compare purchases, having assumed that all variables have been assessed according to a uniform standard to produce the result and that these results are enforceable by consumer laws.

As Finn Peacock has deduced, currently the only real measure of value of a battery storage system is the amortised cost of each KWh absorbed and delivered by the units.

Unfortunately, in the standards world cost cannot be used to determine performance as it is a moving target. So how do we collate all of the variables of a battery storage unit and simplify this to a simple system which allows a customer to compare apples with apples?  Watch this space.

Rob Campbell is Managing Director of Vulcan Energy.

Print Friendly, PDF & Email

  1. Paul McArdle 3 years ago

    The embeddable Battery Finder widget will also be of use to some readers:

  2. Miles Harding 3 years ago

    Then there’s customer behavior.
    This will have a far greater effect than a little fibbing about the battery capacity and degredation.
    Particularly, I see a number of factors for and against over time:

    a) Energy awareness. Apart from some geeks that read meters, the general buying public are clueless about energy consumption. Far too often, the decision is controlled by price, aesthetics and fashion. This is evident from the products on offer and what is seen in the suburbs.

    The positive here is that a consumers energy demand can easily be halved by making good purchase and operation decisions. (education!)

    b) The trajectory of storage technology. Batteries are tracking an aggressive cost reduction curve which will largely solve the storage cost problem with a decade or so. Cheap batteries don’t solve many issues of energy supply.

    c) Improved building efficiency. This has got to happen, but appears to be proceeding very slowly. The building industry is notoriousIy cheap (and often sleazy) and appears to be unable to sell low lifetime operating costs to the buying public. (education! ~ sigh)

    d) Replacement of gas appliances. The present ES situation and LNP nonsense response about gas supplies should be focussing minds on avoiding gas altogether. If not this time, then at the next ‘crisis’ in a few years time.

    The last point has the potential to cause great problems for an electricity supply. The electric kitchen can easily top 10kW with oven, cooktops, kettle and food processors going at once.

    To make batteries work, I feel that consumers should be exposed to the effects of their behaviour.

    Profligate consumers that are insensitive to the capacities of the network should be expected to pay for their ignorance and excesses.

    The other side is the consumer that minimises their overall and peak demand and supplies some of their own energy. Much less network provision is required for them, so they should be rewarded.
    (education and offsets from the profligate consumers)

    There’s nothing like legislation to speed up the education process.

    • MaxG 3 years ago

      Spot on! Why I have given up providing advice to fellow peers, neighbours, etc. simply shocking — had a case recently… I could sense right away they had no clue about anything, and did not really care… almost like: let’s get a battery so we can show off to others… no interest in getting rid of gas, no interest in reducing consumption, wanting to add a pool, 2 more A/Cs, all not considered in the system they bought: 6.5kW/h in panels and a battery, all up 7.5k$.

      • solarguy 3 years ago

        Hearing you Max, I went to another potential customers Macmansion this week to give a quote for PV and it was a similar story to yours, but with a twist. The couple both work and 50% of the time no ones home during the day, but they were chewing 30kwh during shoulder and peak times. I asked if their AC was a big ducted system and the answer came back yes, I knew straight away what they were doing, yep that’s right they leave the AC on when their not home and they confirmed that.
        Now I can give them a system to cover that use as their Macmansion has plenty of roof area facing North (which is facing the street) but oh no, they don’t like the look of PV panels and were disgusted at the thought of having them placed on the front of the house and demanded they be placed East and West. Their Macmansion is 35 meters wide. Hope they have deep pockets!

        • MaxG 3 years ago

          Well, in your case it earns a living… simply go for it; given their usage pattern east/west makes sense to cover the shoulder times.

    • solarguy 3 years ago

      Miles, your saying what I have been talking about for years and naturally I agree with you 100%. Especially point c) My wife works for a building company and no one there gives shit, including customers about energy efficiency. Their not even trying to sell anything remotely like an energy efficient design. Makes my blood boil and yep legislation seems the only thing that will speed up the education process, but then you have to convince the pollies.

  3. Robin_Harrison 3 years ago

    Perhaps a reasonable guide is the warranty provided by makers and guarantees of performance from suppliers.

  4. fearless 3 years ago

    > the only real measure of value of a battery storage system is the
    > amortised cost of each KWh absorbed and delivered by the units.
    > … [but] … cost cannot be used to determine performance

    True. But batteries could have a “Ma and Pa Kettle friendly label” — akin to the EnergyStar labels used in the USA on appliances — that clearly states the number of KWh that can be absorbed and delivered over the lifetime of the product.

  5. Johannes K 3 years ago

    Great idea. How would the comparison work for two batteries with different warranty periods, e.g. one has a 10 year warranty and the other has a 5 year warranty?

Comments are closed.

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