I think they are switching because the old reactor has worn out and it is to expensive to build a new one.

I wonder how far north you can do that. After a while, the amount of solar energy you get i winter will become negligible and no amount of storage will get you through the night.

Note also that their "spring day" is May the 18th, barely a month off the longest day. I wonder what it is like on the 18th December.

I can imagine you could get away with it in California, Arizona, Nevada, etc; but New York ? Oregon ? maybe not.

@calgaryG
Solar has certainly become very inexpensive.
Battery storage has not yet become inexpensive, but the problem is one of bad weather. Sure, you could install enough storage to get you through the night 9 or 10 or even 12 months of the year, but still there will be occasional storms when the sky is dark for several days at a time.
At this stage, you will need an alternative, be it the grid, or a generator. However, this will be expensive as you will have to pay "the grid" to hand around doing nothing for 300 or 350 days a year.
A better approach [IMO] would be to have have enough storage to get you through the night maybe 6-8 months of the year and use the grid for the rest.
This would have a low(er) capital cost while getting good use of the solar cells and batteries (and the grid).

I would think that it would be far better to keep the nukes running and buy less coal fired power from Nevada and Utah. But, of course, that would not satisfy the anti-nuke people in California and the winds mostly blow the pollution from the coal fired plants east away from California.

California’s energy landscape is changing dramatically with energy efficiency, renewables and storage being central to the state’s energy policy.

This is a sick joke.  California has no energy storage worth talking about, and no way to build any in time.  "Efficiency" and "renewables" are grossly inadequate to cope with requirements, and AT BEST will only compensate for what's being deliberately destroyed.

As we make this transition, Diablo Canyon’s full output will no longer be required.

No one could write this in honesty.

Another NPPs operator switching to REs based on lower cost?

It is anything BUT lower cost, but the "alternatives" receive Federal subsidies.  Neither do the "alternatives" pay for their CO2 emissions or for their lack of energy security.  The massive natural-gas leak at Aliso Canyon also lost much of the backup energy supply for California's electric demand peaks this summer.

Shutting down Diablo Canyon is equivalent to adding 3 million cars to the road.  It is an environmental atrocity, a crime against humanity.  Those who decided and those who have agitated for it should be arrested and put on trial.

I think they are switching because the old reactor has worn out and it is to expensive to build a new one.

Diablo Canyon is in beautiful shape.  It is capable of running for at least 60 years of operation.  In 20 years it can be looked at again, and it will probably be fine for a further 20 years for a total of 80 before neutron embrittlement becomes a true problem.

To shut down one of the few remaining 24/7/365 carbon-free generators in the United States makes a mockery of "clean power".  The people who insist on this while forcing nuclear off the grid are not environmentalists, they are the paid stooges of the fossil industry.

I suspect there is a good likelihood that solar systems will become so inexpensive they will become common on residential and commercial buildings and that the owners will use and store as much of their self generated energy as they can and they won't even need to rely on selling surplus back into the grid although they may need to depend on the grid as backup.

No freeloaders.  If you want to signal your virtue with a roof-full of solar panels that can go off-line for days or months in winter, you can pay for your own backup.  If pollution controls and carbon caps won't let you run an internal-combustion engine and the grid has nothing extra for you—tough, you made your choice, you suffer with it.

Give me nuclear.

I too am surprised that PG&E would be shutting down a NPP particularly when many experts are suggesting that more will be required so I'm mainly trying to understand the logic of PG&E who I'm sure has a better understanding of current and future conditions in the electricity business.

The sister of Gov. Moonbeam sits on the board of Sempra Energy.  They both should have been put on trial for treason before this decision was handed down.

Ontario Canada, Quebec, France, Germany, Sweden, Norway, California and many other States/Countries will close older NPPs in the next 5 to 20 years because they are too difficult and costly to refurbish and have very poor population acceptance.

The nuclear industry should find ways to design/produce and install safer lower total cost units. TWRs may be one of the possible solution by 2035+ or so.

Otherwise, large centralized and small decentralized lower cost solar units (with storage) will control a much larger share of the market.

What many are missing is that PG&E has said that the cost of electricity from an upgraded plant after applying for a new license is significantly higher than the cost of new renewable power solar and wind in the latest bids. It is better to use that extra money to invest in lower cost renewables than to upgrade the plant and relicense.

So the pro-nuclear people saying we need to keep this going are saying that California ratepayers should pay a higher rate for nuclear power plant power vs renewables. And on top of that, mid-day when solar covers more than we need and we can't shut down Diablo for a few hours, we should just waste the power. PG&E is saying that does not make sense for ratepayers. And if a money-making entity like them has moved beyond a well-run nuke, I think its a matter of time for all the other nukes to shut down nationwide.