Cheap rate electric to charge powerwall
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It is possible to use AC linked batteries in this way, but, as something like a 10kW battery systenm is about £5k plus fitting, it may take a rather long time to pay for itself?
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Last time I looked at battery storage (to store "free" excess solar PV) I found when you properly accounted for eficciency, battery life and cost of replacement at rnd of life, your "free" stored energy came out hardly any cheaper than normal rate electricity.
You only have the difference between off peak and peak rate, so the saving is even less. I would be surprised if it was economically viable.
You only have the difference between off peak and peak rate, so the saving is even less. I would be surprised if it was economically viable.
Thing is...
Solar & battery storage is a long term strategy, electricity costs will always go up especially due to demand from EV's, the white elephant that is the smart meter and under investment in infrastructure.
Electricity costs will increase sharply in the next 10 years guaranteed!
Solar & battery storage is a long term strategy, electricity costs will always go up especially due to demand from EV's, the white elephant that is the smart meter and under investment in infrastructure.
Electricity costs will increase sharply in the next 10 years guaranteed!
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Theres has been a lot of noise about smart-energy grids - part of the reason for smart meters being installed. Next year it i s planned to roll out the Guranteed export scheme, whereby you can charge up a battery and be paid to release energy during peak times. Figures bandied around vary from 5.5p to 10p per kWh sent back to the grid. Some of the battery manufacturers are talking about charging for very low rate / free, from solar and other green tech. So lets assume you can net 10p per kwH sent back to the grid.
10p x battery capacity x charge cycles is the max you can benefit, so lets say your battery is 10kW usuable capacity and can be fully charged/discharged 8000 times (which is about average at the moment)
10p x 10 x 8000 = £ 8, 000 max earnings so roughly at about £6k for the battery a possible £2k saving (not allowing for inflation) Now 8000 cycles assuming fully discharged once a day = 22 years and roughly 16 years to pay for itself - you would be better off spending money on insulation and other energy saving measures in my opinion. If you have to pay anything for the energy used to charge the battery, then it becomes untennable
Lets say you pay 15p per kWh and battery is charged up from solar panels, so kind of free. That equals £12k total so double your money on a £6k install. roughly 11 years to pay back. Bit more interesting? If you can charge and discharge the battery several times a day, then that improves a lot! But you still have to buy the solar panels....
Neither of these rough calculations allows for energy inflation which does improve all the numbers. Currently this is forecast to run at about 6% per annum. but who knows????
10p x battery capacity x charge cycles is the max you can benefit, so lets say your battery is 10kW usuable capacity and can be fully charged/discharged 8000 times (which is about average at the moment)
10p x 10 x 8000 = £ 8, 000 max earnings so roughly at about £6k for the battery a possible £2k saving (not allowing for inflation) Now 8000 cycles assuming fully discharged once a day = 22 years and roughly 16 years to pay for itself - you would be better off spending money on insulation and other energy saving measures in my opinion. If you have to pay anything for the energy used to charge the battery, then it becomes untennable
Lets say you pay 15p per kWh and battery is charged up from solar panels, so kind of free. That equals £12k total so double your money on a £6k install. roughly 11 years to pay back. Bit more interesting? If you can charge and discharge the battery several times a day, then that improves a lot! But you still have to buy the solar panels....
Neither of these rough calculations allows for energy inflation which does improve all the numbers. Currently this is forecast to run at about 6% per annum. but who knows????
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