Comment by barney54 | Hacker News Reader

Comment by barney54 | Hacker News Reader

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While it is true that solar during the day is a bit more valuable, what really matters is what it is displacing. Check out this document from the California grid operator on page 3. http://www.caiso.com/documents/flexibleresourceshelprenewabl...

In 2013, the average load on the electric grid only stayed in a 2 gigawatt band from midnight through 6pm. When there wasn't much deviation, nat gas combined cycle plants (or nuclear, or coal) can run most efficiently. But by 2020, the growth in solar production in the middle of the day will cause dispatachable power plants (nat gas combined cycle along with nat gas turbines) to deal with a change of 13 gigawatts between 4 pm and 8 pm. This is a huge change in a short amount of time. Thank kind of ramping of power plants is not efficient.

Also note in the graph that the highest system demand occurs at about 9pm. That means that solar does not help cover the highest demand. In this situation, solar does not help reduce the amount of power plants and it leads to the increased use of less efficient (and faster acting) power plants. So while solar seems cheap, it leads to other costs if you want to keep the lights on.

That data is from a day in January, in California. That usually means lots of sun and low air conditioning load. In midsummer, the solar peak and the air conditioning peak occur at the same time, which is convenient. Peak load is on summer hot days. So that works out.

From an economic perspective, one solution is to buy home-generated solar power at the current wholesale rate, which changes throughout the day depending on supply and demand. This is usually lower than what consumers pay, although it may be higher during peak periods.

Since we have a natural gas glut right now, this isn't an immediate problem. Gas turbines go up and down in power in tens of seconds. It's an operational inconvenience, not a big problem. Things will get better if the battery guys ever deliver something cost effective at utility scale.

All correct, all down voted for being unfashionably true.

Dumping lots of solar power during the day makes usually efficient power generation inefficient.

When dealing with countries with a majority of coal-generation (like mine), it's even worse because they can't idle a coal plant, so they just keep it spinning and sell the power at a loss. This drives up the cost of the power for other times to subsidise the loss, and makes the overall market distorted. This then makes large scale capital investment for base load stations risky, meaning that grid instability is a given issue for the future.

The hand-wavers will say 'just use grid storage' - but the truth is that this is an order-of-magnitude more expensive than conventional generation.

When the push for design of energy generation stopped being an electrical engineering issue and became a social engineering issue, the seeds of the problem were sown.

The day when extreme cold or extreme heat shuts down a grid because of insufficient conventional generation will be the day people will realise.

Convert your coal fired plants to natural gas fired plants. It can then be idled, and its pollution controls are much easier to implement and maintain. Did I mention its carbon footprint is lower as well?

Right, natural gas is a good alternative. Base load power and cleaner burning.

But that is an entirely different proposition to subsidising purchase and use of solar panels at above-market rates.

> But that is an entirely different proposition to subsidising purchase and use of solar panels at above-market rates.

I don't think I agree. Fossil fuels have been subsidized for over a century. Are you saying you don't believe renewables should be subsidized to get us "over the hump" until they're a lower cost option? Because I would disagree with that.

We have the opportunity to move to energy that is clean, reliable, and unable to be controlled by a small group of people. We shouldn't just be subsiding it; we should be producing wind turbines and solar flat out like the US produced tanks and aircraft on automotive assembly lines during both world wars.

Through out the day electricity demand fluctuates rapidly[1], talking about a 30-50% fluctuation between 6am and 6pm. I really don't understand your post, the need for reactive plants would still be needed (and used) without solar power generation. The limiting factor is to make sure that solar fits within the band between the baseline constant load and dispatch provider power. As long as Solar isn't forcing Nuclear plants (or whatever the baseline is in your area) to ramp, it isn't a big issue. Gas plants will ramp through out the day due to our usage patterns, regardless of solar production. Only way impact this is storage.

I've also seen people argue against solar because it means that plant will have to run at variable temperatures, meaning less efficiency. This is also not true because gas stations usually output around 200MW a piece, and when you have 10s of these plants scattered you can stagger their shutdowns, allowing power plant operates to run efficiently longer.

[1]http://media.cns-snc.ca/ontarioelectricity/ontarioelectricit...

So, we need more storage on the grid.

Currently, as I understand, practically all residential PV coming online is grid-interactive without battery backup. The power companies actively oppose homeowners installing battery backup systems, because they're concerned about people charging their batteries using cheap power at night, and then selling that power back to the utility during the day. In some cases they have refused to approve PV installations with battery backup for this reason.

As a homeowner, I would find a system with battery backup to be more attractive than one that's useless in a power outage (though, granted, significantly more expensive, depending on capacity). While I understand the utilities' concern, I think there has to be a solution. Doesn't it stand to reason that with all this PV coming online, power prices in the middle of the day should drop, even below nighttime prices? And the prices should be highest on summer evenings? And that such a pricing pattern would supply the correct incentives to owners of PV systems with battery backup?

>Currently, as I understand, practically all residential PV coming online is grid-interactive without battery backup. The power companies actively oppose homeowners installing battery backup systems, because they're concerned about people charging their batteries using cheap power at night, and then selling that power back to the utility during the day.

This is because daytime (especially summer daytime) electricity has a greater profit margin, and power companies demand the right to engage in monopolistic price discrimination.

If power companies charged the same mark-up on electricity at all times of day they wouldn't care if you charged batteries at night and used during the day (and it would probably stop being cost effective, too).

>While I understand the utilities' concern, I think there has to be a solution.

The solution is to treat utilities like utilities again (e.g. nationalize them / regulate more strongly). Privatization and profit seeking behavior in a monopolistic market are responsible for this gross market distortion. They are also the reason why the electric grid won't be upgraded to accommodate solar and wind.

The very fact that there could be somebody out there fighting against green technologies using lobbyists because they are too successful for their liking ought to make every American sick.

And then you're replacing the environmental cost of centralized power stations with the environmental costs of absurd numbers of batteries.

I'd love to see some numbers as to if this would actually be better.

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