In the uk (according to EDF) the average household uses 3100 kWh per year plus 2000 kWh for charging a EV, for me the figures are reversed i use around 3k for charging and 2k for the house, nevertheless that comes to a total of 5100 kWh, which is half the average US household usage btw.
In the uk again, even with the weather here, you only need a 8 kW solar panel system to generate the entire 5000 kWh over a year, the trick is to be able to store it otherwise you are just selling it for cheap to the grid.
Why.
Generating and storing your own energy can be extremely efficient and even liberating, the reasons are besides the scope of this page but i just want to highlight the synergy reason, if you have a electric car for example the cost savings effect is synergetic with a power generation and storage solution so you are likely to have more to gain.
The same with smart thermostats and other new technology, Google’s Nest thermostat for example can sell energy back to the grid when it’s most needed and most profitable for you, Tesla’s Autobidder (that just got approved in the uk) might do pretty much the same.
When.
With the Feed-in-Tarrif ending in March 2019 the playbook was cleared and new rules to facilitate home generation were put into place.
The Smart Export Guarantee (SEG) now requires any licensed suppliers with over 150,000 domestic customers to provide at least one export tariff by the end of the year 2020.
Available since 2019, Octopus Energy was one of the forerunners paying you a 5.5p per kW flat rate, OVO Energy only offers 4p per kW which is three times less than what they charge customers. EDF initially tried to limit the amount of exports they accepted so things were off on a rocky start.
How.
Decide on a home storage solution (keep in mind that battery storage VAT is reduced from 20% to 5% if installed together with solar)
Decide on an installer and make sure they enable you to satisfy the conditions for SEG payments (MCS certified, Smart Meter, Export meter MPAN)
Notify your local Distribution Network Operator, the Energy Networks Association can help you find it at http://www.energynetworks.org
You might need to also notify your local council, good luck figuring wether you have to and where to do that.
Batteries.
All brands listed above have solid hardware, my judgement is on the software and how its integrated with the software, in that regard only Tesla seems to have cared for a full on native - best of class - approach, the offerings from Nissan and Duracell see them even using a outside partner for the software altogether EATON for Nissan and chinese car manufacturer BYD for Duracell