There Is a Point At Which It Will Make Economical Sense To Defect From the Electrical Grid (qz.com)

Michael J. Coren reports via Quartz: More than 1 million U.S. homes have solar systems installed on their rooftops. Batteries are set to join many of them, giving homeowners the ability to not only generate but also store their electricity on-site. And once that happens, customers can drastically reduce their reliance on the grid. It's great news for those receiving utility bills. It's possible armageddon for utilities. A new study by the consulting firm McKinsey modeled two scenarios: one in which homeowners leave the electrical grid entirely, and one in which they obtain most of their power through solar and battery storage but keep a backup connection to the grid. Given the current costs of generating and storing power at home, even residents of sunny Arizona would not have much economic incentive to leave the electric-power system completely -- full grid-defection, as McKinsey refers to it -- until around 2028. But partial defection, where some homeowners generate and store 80% to 90% of their electricity on site and use the grid only as a backup, makes economic sense as early as 2020.

[A]s daily needs for many are supplied instead by solar and batteries, McKinsey predicts the electrical grid will be repurposed as an enormous, sophisticated backup. Utilities would step up and supply power during the few days or weeks per year when distributed systems run out of juice.

Comments

Illogical assumptions

[aaarrrgggh]

The utilities cannot exist as a backup for 3-10% power demand; the cost of delivery would far exceed the cost of energy. Most homeowners would quickly turn to a small natural gas or gasoline generator to recharge batteries. Fortunately, cities don't work especially well for off-grid, so there should be some form of baseload.

By my math, batteries at $250/kWh(B) are comparable to a generation cost of around $0.07/kWh when fully discharged each day. The problem for off-grid is that you are going to want enough batteries that you don't need to start your generator more than a few days per year, which almost doubles your battery count. It quickly becomes poor resource utilization.

I would think that it is far more likely that we will see variable voltage/variable frequency distribution circuits that allow opportunistic load management options: the lower the voltage/frequency the higher the cost, and the greater the incentive to feed back into the grid. With customers having a bi-directional inverter, it becomes easy to manage.

It will also require a change in law

[ronaldbeal]

In many municipalities, being grid connected is required for occupancy. In fact there have been a number of stories of governments condemning "off grid" homes even though the home had all the amenities that a grid connected home has.

What scares me about this

[rsilvergun]

is that those who can't afford solar benefit from the electric grid. When the ones who have money to power their homes themselves what happens to the ones who don't? Does the grid shut down and leave them without power? Probably.

Paying for the backup?

[Bruce66423]

Historically people paid for electricity. Now that they aren't paying for electricity, they will have to pay for the backup supply that they want - or they can go without. The idea that those who are 80% off grid should in effect be subsidised by those who can't leave it is unfair. Unfortunately the implementation of the transition - with a rather severe change in the pricing system to reflect the actual costs of keeping power stations available but not selling electricity - is going to be painful. This will be because the opposition will ally those who have got their solar power / wind power / other supplies to those who are campaigning against climate change, who will argue that the tariff changes will discourage low carbon solutions.