On-grid domestic battery storage

For coastal and inland areas I think LAES rather than CAES is probably best, like the Highview scheme in Slough, which can be scaled up to 200MW/1,200MWh plants.

But, lagoons can provide some balancing/storage for a brief time, as they can be emptied slightly early or late to better match peaks, though this will reduce the maximum amount of energy in that cycle. Basically, they supply leccy for 3.5hrs on each in tide and out tide, so 14hrs per day, and you wait for the optimum time (and head of water differential) to let the water flow from one side to the other, but this can be varied as mentioned.

I've also wondered if they themselves could be used for pumped storage during the brief window when the lagoon is full and the tide is high. At that point you are pumping in at very low head, say from 5m tide outside, to 5m + 'a bit' inside. But that pumped water energy input of 'a bit of a metre' then 'magically' becomes 5 and a bit metres high when the tide goes out giving a multiplayer on the pumped energy.

I suspect my idea is relatively stupid as the opportunity window is quite small, and the cost of the extra kit and complexity, not worth it ...... just a thought.

I think this one is important, well it is to me:

So yesterday was the first really good day in Feb with 7.6kWh of generation - and I managed to get 5.33kWh in and out of the battery as a result
I'm really quite impressed - especially as it's nominally "only" 4kWh of battery capacity - just shows that it'll contribute during the day and if there's enough hours of generation, can still re-charge and catch up again for later on.

I've provisionally estimated that I need 4kWh of useable storage based on:
Summer months useage capped by average 2.5kWh import.
Winter months useage capped by average 1-3kWh of export.
Spring/Autumn months import less than export and around 4-5kWh.

The issue here is that 5kWh is more than 4kWh, but I've always assumed that some of that import will be from variable weather and generation in those months, particularly from clouds, and that storage would allow for lots of small battery cycles as demand and supply vary through the day. My friends e-mail seems to confirm this, which helps guide me on the capacity of battery needed.


Also, thought I'd add this thread on from Navitron, for anyone interested. It's far more complicated and I'd suggest reading nowty's autosig first to get an idea of what he's been up to, and where his experiments are taking him.

Growatt SP2000 Storage System

Staggering savings from the first Powerwall in Australia after 1yr. This is the smaller 7kWh model, not the new 13.5kWh model.

He also has a system that can sell battery leccy to the grid (at a premium) when demand is very high.

Rather jealous!

Living with the Tesla Powerwall for a year: the first Australian case study

Powering the home with electricity in 2015 cost him $2289. But just over a year ago, he invested in a solar power system that has since significantly cut costs.

Nick, a self-confessed Tesla fanboy, was the first person in Australia to buy the company's Powerwall. He bought a 7kW battery, a 5kWp solar array, a SolarEdge inverter and a Reposit monitoring system for $16,790 in January 2015.

A year on and Nick's annual electricity bill has dropped to $178.71 – that's a 92% saving of $2110.

"The aim is to try and export about three times of what I import because my electricity cost is about three times [as much]."

The going rate is 8 cents per kilowatt-hour, but Nick installed a Reposit monitoring system – an $800 extra – that'll push the price up to $1 per kilowatt-hour at certain times.

"So when we had that really hot weather last week, what happened is, there's a peak event on the network and [electricity companies] asked batteries to start dispatching power, so it's kind of like a little power station if you like."

Obviously UK PV generation and seasonality mean we are unlikely to see such savings, but the better these systems do in Australia (and elsewhere) the faster they'll be deployed, and the faster we'll see prices drop. At least that's what I tell myself, with my fingers crossed!

Cardew wrote: »

Selling electricity back to to the grid at up to $1 per kWh helps the figures!!

Absolutely and helps to bring down the wholesale price during these peak times. Perfect.