Four bedroom house. 5 people house.
We have 10kW of solar on roof.
No batteries
4 people home each day.
70% chance we will buy a non Tesla EV in next few months
Living in Canberra (hot summer/ cold winter)
We will have split air con for all rooms.
Is there an equation that I can use to determine (if I get EV ) should I get batteries and if so what size.
I have had a quote for batteries with a 7 - 7.5 yr expected payback time
Cheers
If you're on a ToU tarriff it's still possible to make a battery work even if you don't use solar exclusively to charge the battery. Example being OVO's EV plan - 8c per kWh from 12am to 6am, and 0c per kWh from 11am to 2pm - would let you charge the battery cheaply/freely and discharge during high-cost peak hours.
But it's still hard to make a call without knowing how much is normally being used each day and when. Not really worth it if you're not using anything outside of solar hours but suspect with 5 people it would make sense.
At some point batteries would be cheap enough that even a modest gain would be worthwhile I imagine?
Pretty much what I do. Netzero app for automations, so the battery charges 0-100% 11:00-14:00 from the grid. That's enough to tide us over until midnight when the 8c rate comes in, so basically 'free' use during what used to be the peak rate.
What is your current power bill? and how much are you exporting back to the grid? Should be able to get this info from your power bill.
I'm in a similar situation, going to wait a couple years then get an EV and sort out a vehicle to home/grid charging setup. No need for a home battery then and I can take the battery with me when/if I move.
Forget it about it
What is your insulation like?
Go to your power distributor website and download your usage data. It is broken by down 30 min increments.
With an Excel spreadsheet you can see how much excess you are generating during the day and how much you are using overnight. Get a battery that will fill using excess day time and use it overnight.
Then you need to look at those deals that give you cheap overnight electricity like 8c which makes battery probably uneconomic to cover those hours. So you might just need enough to cover 3pm - 12pm peak.
Go to ChatGPT and upload a couple recent usage bills. Ask it to analyse your bills and provide as much detail as possible on usage, future plans - keep drilling down (i.e. location and EV) and it should be helpful for your situation.
Just need to be aware of the limitations of AI. It is entirely possible that its being trained on misinformation about solar and batteries.
How much power do u use each day? doesnt sound like theres much power left over after your usual usage, so whats the point of batteries, especially if u get an EV.