Mr Purcell admits he initially bought his battery as a form of insurance against the volatility inherent in the spot market.
However, his thinking quickly changed when he saw the opportunities on offer, describing one instance in which he was able to fill up his 10-kilowatt-hour battery with electricity costing 1 cent per unit.
“That’s the opportunity and the risk on the very low prices,” he said.
"It cost me 10 cents to fill the battery during the middle of the day.
“And then at night-time the price went up over $10 a kilowatt hour, so I was able to export that same 10 kilowatts out of that battery for $100.”
I dont think its actually possible now. You can download the amber electric app now if you want it, and monitor the prices.
Its true that the prices can go very low or negative during the day, but if you have solar, that is when your producing anyway, so your excess power gets exported for basically nothing. If your solar is having a bad day (cloudly/rainy/whatever), then everyone elses solar will be as well, and the spot price will be high anyway.
If you fill your battery at 1c, and then export it back at $10, your electricity costs are $10 per kw, so if you end up using more you’ll very rapidly eat away all your profits. So you have to live like a hermit when your battery runs out.
I think this article is just an ad for Amber electricity, there is no evidence of the $10k savings, so I think its just bullshit.
eh, depends.
I mean our solar rig generates on average 3x our daily usage. (No battery as of yet, working towards it). So a big enough battery could quite easily give us the means to store and resell as well as cover night usage in the warmer months.
I can imagine this becoming a full time job itself, just to make sure you don’t get absolutely mauled when the spot price goes through the roof.
If you have a big enough battery you can both use and still export enough to make a significant profit. And for some “living like a hermit” at night isn’t really a big deal, especially since it’s only a few hours.
But yeah, it is complicated enough that most people won’t bother and there is always some amount of risk from being exposed to wholesale prices.
How big a battery do you suggest? I have a 10kWh battery, and its really not enough, especially if the bad weather continues a few days in a row. It wasnt cheap either, and going bigger would only set myself back further.
I guess it depends on your usage, but I don’t really use much more than that for an entire 24 hours so I could see that working for myself (but I’m not a home owner).
But yeah, you indirectly make a point that just buying the battery is pretty expensive and might not come out in your favour (even with wholesale plans). Hopefully they continue to come down in price, and EV vehicle to home and vehicle to grid finally happens.
Vehicle to home should be a huge game changer. I dont need a new car right now, which is why i bought a 10kwh battery, but a car can be 5-7x that capacity. Next car will definitely have v2h, i wont even consider anything that doesnt support it.
I recommend spending money on reducing consumption instead of increasing storage.
There can be astronomical savings on the consumption side - for example my gaming PC draws 400 watts, and my Apple Laptop draws, I shit you not, between 2 and 3 Watts with active use and 200 milliwatts while idle. That laptop is more than fast enough for gaming as well (though being a Mac, I can only play some games). A really intense game might push the consumption up to 5W…
Also, I just don’t plug the laptop in unless the sun is shining - I just checked the battery log (Macs have nice charts for power consumption), and I unplugged at 4:45pm yesterday, used it for about 5 hours last night, and it’s still at 70% charge this morning.
Cooking dinner as soon as you finish work makes a big difference too (assuming you’re cooking on electric?). Also it’s probably better for your health to have a longer gap between dinner and breakfast.
If you find savings like that across all your appliances, especially at night, that 10kWh battery will be a lot more useful.
When I lived off grid (long time ago, when this stuff cost more, on a rural property where the power company quoted a quarter million to run a power line to a new house my parents built) we had a 3kWh battery and it was lead acid, so realistically it was more like 1.5kWh of usable storage - we had an automatic cut off at half charge to protect the cells (it could be disabled, in an emergency). That was more power than we needed - it can be done with efficient appliances. We didn’t even own a backup generator and the half charge cut off was only disabled once, when a battery failed (3kWh was six batteries, not one).
I have spent a lot on reducing our usage, and have basically reached the limit. We have good insulation, modern appliances and overall our overnight usage is pretty good. I am not willing to start removing the things that make life pleasant, such as the TV or my gaming PC (and given how little it gets used it hardly matters), and i work until late, so can’t cook any earlier anyway (and i am still predominately on gas).
Overnight our houses idle usage is ~0.3kwh, so the battery can comfortably last the entire night and then some. But it doesnt change the fact that if there is poor weather for a few days in a row, the battery wont be charged from my solar, and then I have to draw from the grid. And if i am on wholesale pricing, that will wipe out any potential profits from the rest of the year.
When my solar is having a “bad day” it outputs 2kW instead of 5kW. Even in the afternoon when the sun is behind a massive tree that fully shades our panels (and our home, which is why I’m reluctant to cut it down) the panels still generate 600W and that’s far darker shade than any cloud (my home only uses more than 600W when we’re cooking by the way).
So yeah, filling your battery for 1c is a bit of a silly stat. It should be 0 cents to fill your battery. Selling the power back to the grid for a hundred bucks though? That’s totally possible right now.
And in the future I expect you’ll be able to do it with the battery in your car, which you could easily sell while still having enough power left over for the 30 minute drive to work in the morning (and then plug into solar at work).
Out of curiosity, what state are you in? A bad day for me sends my panels to near 0, but I am in Vic. A couple of rainy days and my battery will be empty. Good days will charge the battery and export 10-15kwh to the grid.
The big issue that I have is that my partner works from home, so on bad days her usage is swallowing a lot of the generated power. Not a lot i can do about that, i have made her setup as efficient as I can, but its always going to use more than just an idle house.