The motivation to add batteries to a solar power system is now higher than ever. Governments around the world are lowering their feed-in tariffs and in New Zealand the energy retailers are lowering their solar power buy back rate to a rate so low its almost not worth while exporting solar power to the grid. The possibility of home battery storage being a common household appliance is just around the corner!
In the past adding batteries to a solar power system has been uneconomical for most people, apart from those who are rural and not connected to the grid. But as the solar industry now has a higher demand for batteries in combination with battery technology improving, the cost of battery storage is being driven down.
In the past few years technologies like smart phones and electric cars have also been big contributors in driving down the costs, improving battery technology, improving battery size and weight.
The price of batteries has been declining steadily, around 10% to 15% each year.
According to CleanTechnica, approximately 15,000 German households now use batteries to store their solar power, and that number is snowballing since the costs have come down.
One of the biggest announcements in the last month has been from Elon Musk from Tesla, announcing that they will be making home battery storage systems for people to use in their houses or businesses. The design is complete and the manufacturing will start in around 5 months at the Nevada Gigafactory. Read more about Tesla Powerwall here.
Will this encourage people to go completely off the grid?
To go completely off the grid means that you are always limited to the amount of power you can use. What happens if you have your entire extended family over for Christmas - being off the grid means you don't have the luxury of topping up for those types of occasions.
When you go off the grid you have to make sure you have enough solar panels on your roof and a big enough battery bank to cater for the coldest, darkest period of the year. Then for the rest of the year the system is basically oversized.
It makes more sense for households to be connected to the grid and have a solar panel system and battery bank that will decrease their dependence on the grid, but not eliminate it.
As of June 2018 Tesla power wall batteries were being supplied but not meeting the demand and a backlog of 6 months can be expected by most suppliers.