Archive | Solar power

California Duck Curve. Too much renewables during day, not enough at night

California Duck Power curve

About 6% of San Diego CA power comes from rooftop solar. Even this relatively small amount of solar power creates serious problems on the grid. Once solar hits 15%, the problems get more pronounced. This is not just blather from utilities resisting change. When it gets dark, utilities have to ramp up other types of power quickly, something which not trivial. The Duck Curve for California for 2015 is moderate, as shown in the image. As more rooftop solar is installed, the curve becomes more pronounced.

More solar is produced during the day when people aren’t home. This production vanishes when they come home, as night falls, precisely when more power is needed. Also, the glut of production during the day can cause prices to be actually less than zero as well as creating grid problems, since the grid must always be in perfect balance between supply and demand.

As in most locales, solar output in California peaks in the naturally sunny middle of the day. But lots of people are at work and there isn’t much demand on the system. SDG&E’s system peaks closer in the evening, when people get home from work and the sun goes down. The drop in solar production almost perfectly coincides with the utility’s daily ramp up to peak demand.

The San Diego utility says solar rooftop users only pay about half of what their solar costs the company. This is probably at least partly true, made worse by a convoluted state-mandated rate structure. Time-of-use rates probably make more sense. Users would pay more for power on a baking hot summer afternoon than on a moderate Spring night. The ability to store power for a few hours would help enormously, however doing so is expensive. Other solutions though, are available now.

Avery imagines a world where your house pre-cools during the off-peak, where your electric water heater delivers demand response during the peak, and your electric vehicle charges based on price signals.

“All these things today are reality. They can happen right now,” he said.

Posted in Renewable energy, Solar power0 Comments

Tesla plans solar-powered home battery storage

Tesla, perhaps to distract from lackluster car sales, just announced plans for battery packs powered by solar panels for residential homes. This is not a new idea. Off-grid homes as well as grid-connected homes with solar panels already have batteries to store energy. So really, why is this news, except that Tesla announced it with great fanfare and says the batteries will look elegant. The amount of hype emanating from Tesla has always made me a bit suspicious.

Working with SolarCity (of which Musk is Chairman) to power the batteries with solar energy just makes the whole endeavor sound like a fantastically Earth-friendly project.

Um, no. Batteries by definition are not earth-friendly at all. They require mining, often in impoverished areas where workers are exploited, use noxious chemicals, and are difficult to dispose of. So don’t go hugging trees quite yet because of the not really green at all Tesla home battery. Is it better than powering your home with coal power? Absolutely. But it’s not green. Batteries probably never can be.

Another problem is the utilities, some of whom are dinosaurs that don’t want to lose revenue because people install solar.

Unregulated batteries to power homes attached to solar panels that keep the battery charged mean some annoyed executives at utilities, especially if the battery’s storage is large enough that it wouldn’t even need much in the way of the electric grid to supplement the solar panels. Not that you’ll ever hear it spelled out so bluntly. Tesla has said that utilities are partners, not enemies, but arguably that just depends on where you look.

Smart utilities, like Green Mountain Energy in Vermont, are leading the move towards home solar. And yes, home batteries do need some regulation. For example, they must never ever send power grid into the grid during a blackout to prevent electric shock to linemen fixing, say, downed power lines, who aren’t expecting power to be coming upstream to them.

Stored power from home solar is a great idea. Let’s hope it becomes ubiquitous soon. For that to happen, the grid will need to be rejiggered to handle distributed energy  flowing from many places to many places rather than the centralized system we have now.

Posted in News, Renewable energy, Solar power0 Comments

Distributed generation increases electrical grid security

Power Lines

A few well-placed attacks could paralyze the existing US electrical grid, says former FERC Commissioner Jon Wellinghof. The best way to defend against such attacks, he says, is with distributed generation, not bigger walls and increased security. This is precisely where renewable energy, especially rooftop solar, can help.

Wellinghoff believes the true answer to grid security is to fundamentally realign the system from one that relies on a few nodes (probably less than a dozen), which are all critical for the grid to operate, to a national system of ‘distributed grids’; hundreds of smaller ones, which of course could be attacked individually through conventional or nuclear or cyber means, but none of which could topple the entire system if it went down.

Wellinghof focuses on substations as being particularly vulnerable, and they are. However, another area of concern is ginormous transmission towers sited in remote areas, as often happens in the American West. Presumably taking down a couple of those towers would create chaos. However, those towers generally come from huge power plants so again, distributed energy lessens the threat because power can be generated everywhere.

Distributed generation is about moving power generation to within the load centers as opposed to power sources being remotely located from the load centers. This breaks up the centralized node architecture currently in place and disperses the generation across the grid forming micro and sub-regional grids. So if there is an attack on a node it won’t take down that whole area of the grid because there would be those sub-regional and micro-grids that could island themselves within those areas.

If everyone had solar panels on their respective roofs then we could adequately disperse power generation in such a way that it makes nodes practically irrelevant. It is easy to hack into a node and cause it to malfunction but it is basically impossible to hack 10 million solar power systems.

Posted in Renewable energy, Solar power0 Comments

Ivanpah solar power plant generating way less power than expected



The Ivanpah concentrated solar power plant in the California Mojave desert near Primm Nevada is not producing nearly as much electricity as predicted. Natural gas, not the heat of the sun, is being used more than originally projected to power the turbines. CSP works by reflecting the heat of the sun from heliostat mirrors to a central tower to run the turbines. Ivanpah has produced a mere 25% of expected electricity since December 2013 when it began production, a dismal result indeed.

The scale of Ivanpah is much larger than any other CSP plant. The plant operator says the weather wasn’t as sunny as expected. This seems a bogus excuse. Was there really 75% less sunshine than projected?

[Second quarter] sales totaled 133,807 MWh and at an average price of $167.85/MWh that generated $22.46 million in revenue.

That relatively small output, combined with the project’s $2 billion price tag, could no doubt hurt all three Ivanpah owners

Increasingly, CSP is having trouble competing with solar PV. If Ivanpah continues to under-perform, then future CSP plants may not get funded. . Ivanpah was funded by NRG Energy, Google, and BrightSource Energy primarily by using a $1.6 billion federal loan guarantee. If Ivanpah continues to falter and the federal government get stuck with the loan, it’ll seriously affect renewable energy funding going forward.

Another sign of the plant’s early operating woes: In March, the owners sought permission (PDF) to use 60 percent more natural gas in auxiliary boilers than was allowed under the plant’s certification, a request that was approved in August.

Using much more natural gas to produce energy rather than using solar heat as planned could, if it continues, might make Ivanpah not able to qualify as being renewable energy under the California plan for 33% in-state renewable energy by 2020. Plus, it’ll make foes of renewable energy chortle with laughter.

Some CSP plants store excess heat in underground molten salt caverns and thus can product energy when the sun isn’t shining. Inexplicably, Ivanpah doesn’t do this, a decision probably made to save money. In retrospect, this seems short-sighted and may imperil the entire project.

Posted in Renewable energy, Solar power

Mandalay Bay in Vegas now has 20 acres of rooftop solar


The Mandalay Bay casino and convention center in Vegas is ginormous. MGM Resorts, who owns it, has installed 21,324 photovoltaic panels on twenty acres of convention center roof. Yes, twenty acres… The 6.4 MW system will provide 20% of power for the center, with an additional 2 MW coming when the convention center is expanded. Well done, MGM.

How big is Mandalay Bay? The main hotel is upscale. Delano, an even-more upscale hotel, is in a separate building. A super-upscale Four Seasons occupies five floors of the main hotel. The casino is 135,000 sq ft, The convention center is 1,000,000 sq ft. An events center has 12,000 seats. There are 30+ restaurants, shopping malls, multiple bars and other venues. Plus, Mandalay Bay connects to Luxor (semi-upscale) and Excalibur (low-end),  which are also owned by MGM.

The project is being done in partnership with NRG Energy. Once it is complete, Mandalay Bay will buy from NRG the solar energy through a Power Purchase Agreement at prices below the peak rates on the traditional NV Energy electrical grid (Based in New Jersey, NRG is also a major partner in the Ivanpah solar plant that opened earlier this year near Primm, Nev.).

Posted in Renewable energy, Solar power

Hawaii grid can’t handle the demand for solar, slowing installations


There is a huge demand for rooftop solar in Hawaii. However, the grid is barely able to handle the current amount of solar power. The utility has cut way back on new permits and the solar industry is losing workers. The problem, of course, is that solar is variable. When the sun shines, thousands of rooftop systems produce power, and some of it goes back into the grid.

HECO says it is not deliberately trying to hurt the solar industry. Rather, the utility is seeing a growing number of circuits exceeding 100 percent of minimum daytime load during the daytime in residential areas. On the Big Island, HECO says that 10 percent of circuits had reached unstable levels as of February of this year.

“This is a difficult technical issue, and we’re not aware of another utility in the world that has addressed it. There’s no model for us to follow, no resource for us to tap into. We’re really creating new frontiers on this,” said Jay Ignacio, president of the HECO subsidiary HELCO.

Reform is coming, forced on HECO by impatient politicians and homeowners who accuse the utility of being deliberately lethargic. Circuits will be beefed up. Customers will get full net metering rates. However they will pay monthly fees for grid costs.

Posted in Renewable energy, Solar power

Ivanpah planning multiple ways to stop frying birds



Reflected heat from mirrors at the Ivanpah solar thermal plant in California near Primm NV has been killing large numbers of birds. To their credit, site operator BrightSource Energy is creating bird deterrent systems. These include anti-perching devices, sonic deterrents, anti-bird LEDS,  and waste and water containment so birds don’t gather.

As to the efforts currently underway, the waste and water containment is actively being done daily and the heliostat repositioning is complete. The sonic deterrent has been purchased and is in the process of being tested on site. The lighting on the towers are now being turned off at night and bids to replace the current ground level lighting with LED were returned this week and will be purchased and installed.

They also plan to donate $1.8 million to cat trap, neuter, and release organizations as cats kill birds too. Current efforts include a “25 million for our desert tortoise program, and in developing a high quality, scientifically valid, and robust avian plan.”

I don’t quite get the advantage of solar thermal, which reflects heat to a central tower to power turbines, over solar photovoltaic. PV is not nearly as destructive to wildlife and birds and uses practically no water, an important issue in baking deserts. Another problem with Ivanpah is airline pilots report the glare can be blinding.

Posted in Renewable energy, Solar power

California could be 100% renewable energy by 2050, say researchers


A combination of renewable energy from wind, water, and sunlight could power California completely by 2050, say perky researchers from Stanford. In my view they’re a bit too perky as well as overly We Know What Is Best For You.

First off, all those pesky gas and diesel vehicles would need to be completely replaced by electric, they say. No word on how electric semis would be able to haul multi-ton loads up the steep Grapevine outside of Los Angeles. No electric truck to my knowledge has the needed torque and power to do this. Maybe they will one day. But they don’t now.

Then there’s this.

[Wind, water, and sunlight] sources selected “ranked the highest among several proposed energy options for addressing pollution, public health, global warming, and energy security.”

Um, shouldn’t cost be a criteria too? Also, grid technology neccessary to support 100% renewables doesn’t exist yet. Perhaps it will soon. However, making projections based on technology that doesn’t exist yet seems a bit specious.

They claim going to 100% renewables would pay for itself.

“The California air-pollution health plus global climate cost benefits from eliminating California emissions could equal the $1.1 trillion installation cost of 603 GW of new power needed for a 100% all-purpose WWS system within ~7 (4–14) years.”

“Global climate cost benefits”, whatever that might be, do not pay for the project or decrease costs eleswhere and should not be included in cost calculations.

Posted in Renewable energy, Solar power, Wind turbines

Self-cooling PV cells use layer of silica glass


Stanford researchers have developed a way to keep solar photovoltaic cells cooler, even in baking temperatures. If the cells get too hot, efficiency drops as does the lifetime of the cells. Adding pyramid-shaped layer of silica glass allows the cells to cool on their own, avoiding the need for water or wind for cooling.

“The goal was to lower the operating temperature of the solar cell while maintaining its solar absorption,” Fan said. “We were quite pleased to see that while the flat layer of silica provided some passive cooling, the patterned layer of silica considerably outperforms the 5 mm-thick uniform silica design and has nearly identical performance as the ideal scheme.”

Thus, efficiency and cell lifetimes both increase, hugely improving productivity.

Posted in Renewable energy, Solar power

Ivanpah Solar Thermal Plant in Mojave Desert



The ginormous Ivanpah Solar Electric Generating System in California near Primm NV reflects baking heat from the sun to a central tower where electricity is generated from steam turbines. Some solar thermal plants store excess heat in molten salt to be used later to generate power. Ivanpah doesn’t do this. It doest recycle 100% of the steam, keeping water usage at a minimum. However, the concentrated heat does kill birds and the glare can be an aviation hazard. No source of electricity creation is completely benign. That’s just the way it is.


Posted in Renewable energy, Solar power


Bob Morris


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