Battery storage feasibility


But I’m not paying 59c/kwh - because I’m not using any peak power. I’ve chosen my plan for minimum off-peak and shoulder rates, and maximum FIT, to minimise my bill rather than make a comparison point . Looking through the plans with peak ~30c - 40c, they all have much higher off-peak rates, and I’d be much worse off.
FWIW, I plugged my last bill’s usage figures into the wattever comparison site, and out of the ~100 various retailers and plans it worked through, the plan I’m on came out to be the minimum bill - with annual costs on all those 100 plans and retailers ranging from $399/year on the plan I’m on, up $1972/year on a plan with stupidly high off-peak rates.
When you have solar+battery, you choose your plan for lowest off-peak rates, because the peak rate is irrelevent.

I didn’t realise QLD rates were that low :slight_smile: , until looking through that article and doing some deeper digging to independently verify the claims. Doesn’t seem fair, with QLDers having more sun to play with to offset the rates!


Bottom line is that for the article you linked, it uses a dodgy comparison to a flat-rate tariff thats also significantly lower that other places in the country, that might be relevant in QLD (but you’d still compare with the off-peak rate of a TOU plan rather than a flat-rate tariff) but is an irrelevant and misleading comparison for people outside QLD - something not highlighted in the article.

Its certainly true that a financial case is marginal for many at the moment for sure, but its devilishly hard to quantify generically.

There’s actually a case that the energy retailers should be funding end-user batteries, as the main benefit is to the retailers rather than the end users.
If you checkout the NEM wholesale prices varying throughout a day ( at, the daily wholesale price almost always spikes high at sundown, when solar slips to zero and fossil-fuel gen needs to pick up the slack (spikes not so high today, but during high temps with large-scale aircon draw a few weeks ago its very noticable). That is precisely when home batteries will step in and fill in the transition, even small batteries - the size of the battery would determine how long after sundown before the grid had to step in for that house, so the transition would be much more gradual and predictable for fossil-fired generators over a large population.
The result would be significantly reduced wholesale prices during those peak hours 1-2hours before to 1-2 hours after sundown, which would be savings for the retailers purchasing the wholesale power to distribute - and that could help out all power users, not just those with the batteries, as it will be a whole-of-grid stabilising/smoothing effect.


I agree you choose the plan that makes sense when you have solar + battery.

But the comparison then needs to be made with the best plan you can get when you have solar only, or the best plan when you have neither.

That’s when you realise the battery is a really crummy ROI.

Yeah, I’ve done that too. Fed it precise data on all energy flows.

It didn’t even come close to showing me the best plan option, by some $100/qtr.

That’s because it doesn’t include all the retailers’ offers. In my case it omits EnergyAustralia entirely, who have the best rates for my situation by far. If I was choosing my retailer on the basis of that comparison site, I’d be throwing thousands of dollars away.