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You're assuming that the battery needs to store the total energy requirements of a house for the entire year. Much of the time the energy needs can be met by co

by harg 5y ago

You're assuming that the battery needs to store the total energy requirements of a house for the entire year. Much of the time the energy needs can be met by conventional energy generation (wind turbines, solar, hydro, etc) and the battery is only called upon when there's a shortfall. So you'd only need a fraction of the annual consumption to make it useful. The whole idea is to make renewables more effective by storing the excess. Grid storage will be an important part of the transition to renewables. But yes, it is expensive, but it's only at the R&D stage. I'm sure could be made cheaper, and the article mentions reducing the cost to $6/kWh.

t0mas88 5y ago
If you use solar power in a climate like Germany you will get that kind of math. Let's say you use 8000 kwh per year, and you have the solar capacity to create 8000 kwh per year. Assume you already have a normal home battery of ~14kwh so day/night is not an issue, the solar production during daytime charges the battery and all night time power comes from the battery. Now your big problem is that 70% of the 8000 kwh solar per year is produced from May to September. You need 670 kwh per month for usage, so in those four months you have just under 3000 kwh too much. Then in April and October the panels roughly produce what you use. And November to March you have a total shortfall of 3000 kwh. So you need seasonal storage capacity of about 3000 kwh to be able to run an 8000 kwh yearly usage on solar in this climate. The other option is to buy much more solar panel capacity than you need, then you can use a smaller battery which in total could be cheaper since solar panels aren't that expensive anymore.
- Gasp0de 5y ago
  I use 6000/8000kWh between September and May though, because that is when I'm using a Heatpump to generate electricity.
- PaulDavisThe1st 5y ago
  > The other option is to buy much more solar panel capacity than you need, You need the space to install them also. I have a 6.6kW array, and would need 3x that capacity to heat my home using electrically-powered air source heat pumps during the winter months. Even with 0.75 acres / 0.30 hectares, that would be quite a lot of my property covered by panels, and way more than could ever feasibly fit on the roof (the current array is ground mount).
  - t0mas88 4y ago
    Good roof space may become a sales argument for houses in the future. Mine happens to have a huge flat roof slightly sloped to the south. I have 8 kW solar and that’s less than half the roof covered.

by harg 5y ago

t0mas88 5y ago

If you use solar power in a climate like Germany you will get that kind of math. Let's say you use 8000 kwh per year, and you have the solar capacity to create 8000 kwh per year. Assume you already have a normal home battery of ~14kwh so day/night is not an issue, the solar production during daytime charges the battery and all night time power comes from the battery. Now your big problem is that 70% of the 8000 kwh solar per year is produced from May to September. You need 670 kwh per month for usage, so in those four months you have just under 3000 kwh too much. Then in April and October the panels roughly produce what you use. And November to March you have a total shortfall of 3000 kwh. So you need seasonal storage capacity of about 3000 kwh to be able to run an 8000 kwh yearly usage on solar in this climate. The other option is to buy much more solar panel capacity than you need, then you can use a smaller battery which in total could be cheaper since solar panels aren't that expensive anymore.

Gasp0de 5y ago
I use 6000/8000kWh between September and May though, because that is when I'm using a Heatpump to generate electricity.
PaulDavisThe1st 5y ago
> The other option is to buy much more solar panel capacity than you need, You need the space to install them also. I have a 6.6kW array, and would need 3x that capacity to heat my home using electrically-powered air source heat pumps during the winter months. Even with 0.75 acres / 0.30 hectares, that would be quite a lot of my property covered by panels, and way more than could ever feasibly fit on the roof (the current array is ground mount).
- t0mas88 4y ago
  Good roof space may become a sales argument for houses in the future. Mine happens to have a huge flat roof slightly sloped to the south. I have 8 kW solar and that’s less than half the roof covered.