Cheap Panels Changing the Game for Big Solar

Developers are moving toward photovoltaic panels for utility-scale solar plants

Photovoltaic Panels at a PG&E's Dixon-Vacaville array. (Photo: Craig Miller)

Photovoltaic solar panels are becoming the new black for large-scale solar projects in California.

Developers of what’s billed as the world’s largest solar project, spanning 7,000 acres in Blythe, California, say the plant will get half of its 1,000 megawatts from photovoltaic panels. This recent announcement makes Solar Trust of America the fourth large-scale solar developer in California to switch from solar thermal to photovoltaic panels, which Solar Trust CEO Uwe Schmidt calls “the right technology at the right time.”

Brett Prior, Senior Analyst at Greentech Media, says that large-scale solar developers have preferred solar thermal but the plummeting cost of photovoltaic panels is changing that.

“Over the last couple of years PV [photovoltaic] panels have dropped significantly in price,” says Prior.

How’s 70% over the last two years for “significant?” Prior says that’s because China is emerging as a major player in panel manufacturing. “Just in the last five years, China has gone from sort of a minimal role to over 50% of all worldwide manufacturing of PV panels.” says Prior.

However, cost of technology isn’t the only factor affecting large-scale solar projects.

“One area where [solar thermal] players are making a lot of progress is incorporating thermal storage,” says Prior.

For some solar developers, thermal storage is a viable feature for solar thermal power and worth the extra cost. Since solar photovoltaic panels only work when the sun is shining, some solar-thermal plants incorporate a feature that uses molten salts, which can store heat throughout the day and be released to generate steam for turbines.

Prior says solar-thermal plants using storage features allow more flexibility to grid demand, which is consistent after the sun sets.

“They can store energy during the morning when it’s not really needed by the grid, deliver 100% output at one p.m. when it’s most needed, and continue to deliver 100% output at eight p.m. when electricity demand drops off,” says Prior.

Despite the emerging energy storage technology, three other large-scale solar plants (links to interactive map, below) have made the transition from solar thermal to solar photovoltaic panels for at least part of the project. Other developers like NextERA’s Beacon Solar, builder of a large project in Kern County, have suggested similar plans.

View Making the Swtich in a larger map

  • http://mark-nano.blogspot.com Mark Wendman

    PV is cheaper per published specifications, but power quality gained by using molten salt concentrated solar thermal, means that the power produced both has overnight capability, and immunity to minor cloud transients dropping power for a few minutes, that with naked PV creates havoc – short term instability to the power of the grid.

    Without storage, PV power is hobby grade, and yet to add energy storage to PV (photovoltaics) is hugely more costly than adding (storage) tanks with Molten Salt Concentrated Solar Thermal. With improvements to the formulations of Molten Salts, the practicality is immeasureably better, and MS Conc Solar Thermal, power storage and buffering is HUGELY cheaper than doing so with PhotoVoltaics.

    You can make superior solar photovoltaic cells, but any viable power storage / buffering is so costly as to render baseload power from PV uneconomical.

    Solar Millenium had a crappy low concentration solar thermal power plant design, and as such was not competitive with Molten Salt at high concentration and with easy power storage of high concentration Molten Salt Solar Thermal ( power tower designs, like Brightsource’s new plant proposal using a central tower receiver and articulated 2 axis mirror arrays aiming at a central tower receiver ).

    In time Photovoltaic electrical energy storage will improve, but will unlikely ever reach the storage costs of high concentration Molten Salt Solar Thermal, with storage costs merely adding a large MS tank – versus the complexity and costs of a large scale electrical battery / flow cell of ANY kind.

    Brightsource has this right ( Molten Salt Solar Tower with easy cheap baseload power / energy storage), Solar Millenium has made a huge strategic mistake, as their costs to eventually create Baseload electrical power from photovoltaics, using any kind of battery or alternative energy storage that goes round trip to electrical, will be uneconomical with PV – uncompetitive with Brightsource.

  • Brian

    Actually, with resistive heaters you could use the very same molten salt storage technologies with PV. Of course you wouldn’t want to pay for a turbine that wasn’t fully utilized so it would be preferred that somebody build a CSP plant somewhere within a reasonable proximity to the PV plant.

    • http://mark-nano.blogspot.com Mark Wendman

      Indeed technically you can do as you suggest, but it would not be even remotely cost competitive with high concentration Molten Salt Solar Thermal.

      This large cost burden of your concept, arises since you’d have to add to your proposal an otherwise extraneous storage function / (costly) turbine generation, in your Molten Salt / Steam turbine for Molten salt steam to electric generator loop.

      If you give it some thought, at the intended scale PV + your proposal for MS would be hugely expensive. Nevermind your proposal would be considerably less efficient overall. It is not as simple as you say, even if buildable, it is likely not even remotely cost competitive.

      High concentration molten salt solar tower ( + storage tank ) is likely singular in being very low cost baseload solar, and easy technology NOW.

      Brightsource’s team got this pretty quickly ( migrating from low concentration solar thermal less capable of storage, to high concentration Molten Salt easily capable of thermal storage ).

      Solar Millenium instead of migrating from solar thermal trough ( low concentration ) ditches solar thermal, when they really need to go high concentration solar tower molten salt just like Brightsource.

      In time the power operators PG&E and brethren will need at large scale, BaseLoad (stable) quality solar electrical grid power of any stripe / variant.

      Brightsource will have proven to made the right technical decision for lowest cost baseload solar power of any kind ( ie instead of costly electrical storage at grid scale needed for PV, they just add a large Molten Salt tank for thermal energy storage )

      The key to high concentration solar tower molten salt & storage, is that versus Trough based low concentration solar thermal ( prior gen of solar thermal) ,

      you reduce overall piping with a high concentration solar thermal tower, you increase operating temperatures ( to >500c possibly closer to 1000c ) resulting in higher operating efficiencies at higher concentration,

      and just by adding a storage tank, the primary ( initially non storage) power generation / solar capture loop, is leveraged by the storage tanks, with no added turbines as your proposal requires

      ( ie your PV + resistor heat dump, MS loop and storage tanks and then added costly turbine power loop is needed for your proposal, but in MS HCSTP, the turbines are already there ! – hence free for the added storage function in MS HCSTP, but a huge added expense burden for your proposed scenario )

      So while you can “technically” do what you propose for PV energy storage via proposed MS storage & power loop, it will add a huge expense in a PV photovoltaic power plant, and by contrast, storage in MS HCSTP is just the cost of a storage tank, leveraging the turbines already there.

      I hope I am explaining this clearly enough.

      You are right technically, but incorrect on even remote cost competitiveness of your idea. In short your proposal impractical even if technically possible.

  • Craig Miller

    We’ve also been seeing projects designed as solar-natural gas hybrids, for this very reason. You give up some of the carbon footprint shrinkage but gain grid flexibility.
    This article is a year old but you get the idea:
    http://bit.ly/aITKCl

  • Philip Ngai

    The most important thing Brightsource got right at Ivanpah was choosing a site near a natural gas pipeline so that they can have a reliable, 24×7 source of heat for their turbines no matter what the weather, day or night.

    In other words, its a gas burner with a solar supplement.

    • http://mark-nano.blogspot.com Mark Wendman

      steam turbines ( the Molten Salt configuration is heat transfer to s steam loop is probable ) are not likely convertible to efficient gas operation?

      BrightSource’s 2nd project using molten salt & energy storage derived from same at power tower high conentration / high temperatures is far better on many levels than you or the other fellow ( and many others ) comprehend.

      The 2nd Brightsource project is an optimal design formed of best engineering and cost / performance tradeoffs, imperfect storage, that does the first order requirements for true baseload quality grid scale power, yet does not burden the project with any expensive “electrical” / battery storage ( or grid scale auxiliary turbines as needed with the prior fellow’s PV / Molten Salt ) – that would raise costs for “proposed” PV / MS storage baseload power far far higher than any costs associated with the new Molten Salt High Concentration Solar Thermal tower collector & added thermal storage tanks…used in the new BrightSource project.