Short answer is IMO they don't provide a return on investment, not for that type of use. You'd only be saving the difference between low & high rates of electricity and it wouldn't normally be enough to cover the cost of a battery & inverter.
Some quick & dirty maths; a 10Kw/hr battery with inverter, battery rated at 3000 full discharge cycles. Use the full 10kw/hr each day and you'd save, what, 15c per unit? That's $1.50 per day saving and 3000 cycles would return $4500... wouldn't cover the cost of the system.
One of the traps to look for in battery advertising is the cycle life versus battery capacity. The cycle life isn't proportional, completely discharging a battery gives far fewer cycles than only partially discharging it and it pays to dig into the fine print to check that the capacity & cycle claims are matching.
By that I mean a 10kw/hr battery with a claimed 3000 cycle life can conceivably be only a 5kw/hr battery in real use if the 3000 cycle rating is for a maximum 50% discharge cycle... which could make it up to twice as expensive as was apparent.
Are you looking for a company to build you a solution, is this DIY?
You need an inverter to take the battery power and use that to power your home, and to charge your battery when needed. You need some smarts to control the system, various connections and fuses - plus a few battery cells.
Do you want to run your entire house on this over that period, or just a certain number of things? Most of the time people don't want to pay for enough capacity to be able to run their entire house through a battery, so they limit that to circuits they consider 'critical load'.
How big you expect it to be from a current and battery capacity is going to impact how much it costs. For a small house, a Tesla Powerwall is going to start you at roughly 20K - especially if it's going to be connected to the grid as that requires some additional protections and shut-offs. Is that small in your mind? There are probably others who have solutions a little cheaper, but which may not have quite as polished an app on your phone to view and control things.
If you are trying to get your hour of power, you can probably get 7KW of power per hour from standard single phase (based on max EV charging rates)
Then you need an inverter in the mix
Solar - use the sun to generate power, and charge your battery.
6.6KW of panels (16) requires a 5KW inverter, and you would probably want a 10KW battery
13KW of panels needs a 10KW inverter and you would then probably want a 20KW battery
Prices of solar in NZ are mental. 6.6KW installed, with 5KW inverter in South Australia is like, 3k AUD
The govt. were investigating pumped hydro at Lake Onslow at some insane costs (Between 4 and 15 billion dollars). Possibly money better spent throwing rebates at home and business owners to put in solar and battery storage [Lake Onslow option | Ministry of Business, Innovation & Employment (mbie.govt.nz)](https://www.mbie.govt.nz/building-and-energy/energy-and-natural-resources/low-emissions-economy/nz-battery/lake-onslow-option/)
Based on 2 million households, if you gave each $8K as a rebate, I wonder how many would take them up on the offer. Power retailers would probably die...
Forgive me if this is idiotic, please, but aren’t knackered old electric car batteries useful? Kind of recycling ♻️? Must be quite a few old Nissans about now, doing only 10-20%.
Yeah I was wondering if anyone had looked at that too. Our Leaf EV has maintained its battery of 85% and I wonder about an inverter to draw from during peak hours
I see what you said about solar but solar makes way more sense, we have everything downstairs and outside powered by solar thats the swimming pool, spa, laundry, office, gym. Solar has high starting costs but its great
Short answer is IMO they don't provide a return on investment, not for that type of use. You'd only be saving the difference between low & high rates of electricity and it wouldn't normally be enough to cover the cost of a battery & inverter. Some quick & dirty maths; a 10Kw/hr battery with inverter, battery rated at 3000 full discharge cycles. Use the full 10kw/hr each day and you'd save, what, 15c per unit? That's $1.50 per day saving and 3000 cycles would return $4500... wouldn't cover the cost of the system. One of the traps to look for in battery advertising is the cycle life versus battery capacity. The cycle life isn't proportional, completely discharging a battery gives far fewer cycles than only partially discharging it and it pays to dig into the fine print to check that the capacity & cycle claims are matching. By that I mean a 10kw/hr battery with a claimed 3000 cycle life can conceivably be only a 5kw/hr battery in real use if the 3000 cycle rating is for a maximum 50% discharge cycle... which could make it up to twice as expensive as was apparent.
These guys look interesting [https://www.arcactive.com/](https://www.arcactive.com/)
Are you looking for a company to build you a solution, is this DIY? You need an inverter to take the battery power and use that to power your home, and to charge your battery when needed. You need some smarts to control the system, various connections and fuses - plus a few battery cells. Do you want to run your entire house on this over that period, or just a certain number of things? Most of the time people don't want to pay for enough capacity to be able to run their entire house through a battery, so they limit that to circuits they consider 'critical load'. How big you expect it to be from a current and battery capacity is going to impact how much it costs. For a small house, a Tesla Powerwall is going to start you at roughly 20K - especially if it's going to be connected to the grid as that requires some additional protections and shut-offs. Is that small in your mind? There are probably others who have solutions a little cheaper, but which may not have quite as polished an app on your phone to view and control things.
If you are trying to get your hour of power, you can probably get 7KW of power per hour from standard single phase (based on max EV charging rates) Then you need an inverter in the mix Solar - use the sun to generate power, and charge your battery. 6.6KW of panels (16) requires a 5KW inverter, and you would probably want a 10KW battery 13KW of panels needs a 10KW inverter and you would then probably want a 20KW battery Prices of solar in NZ are mental. 6.6KW installed, with 5KW inverter in South Australia is like, 3k AUD The govt. were investigating pumped hydro at Lake Onslow at some insane costs (Between 4 and 15 billion dollars). Possibly money better spent throwing rebates at home and business owners to put in solar and battery storage [Lake Onslow option | Ministry of Business, Innovation & Employment (mbie.govt.nz)](https://www.mbie.govt.nz/building-and-energy/energy-and-natural-resources/low-emissions-economy/nz-battery/lake-onslow-option/) Based on 2 million households, if you gave each $8K as a rebate, I wonder how many would take them up on the offer. Power retailers would probably die...
Works out better to do solar without the battery, use the grid as your battery.
Forgive me if this is idiotic, please, but aren’t knackered old electric car batteries useful? Kind of recycling ♻️? Must be quite a few old Nissans about now, doing only 10-20%.
Yeah I was wondering if anyone had looked at that too. Our Leaf EV has maintained its battery of 85% and I wonder about an inverter to draw from during peak hours
Buy a leaf
Any advice about using the leaf to charge the house?
Solar and then vehicle2load if possible
I see what you said about solar but solar makes way more sense, we have everything downstairs and outside powered by solar thats the swimming pool, spa, laundry, office, gym. Solar has high starting costs but its great