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News and Insights

June 08
Vaisala Supports SunEdison, TerraForm in $2.4B First Wind Acquisition

Prior to the acquisition of a large number of assets in any industry, it is imperative that the value of those assets is accurately assessed and quantified. When the assets involved are wind projects both fueled and impacted by the weather, bringing in an expert to translate weather information into energy production estimates and project valuation decisions is vital.

Today we announced the critical role we played in supporting SunEdison Inc., and its power-plant holding company, TerraForm Power Inc., in the $2.4 billion purchase of First Wind Holdings Inc. in late 2014.

With the purchase of First Wind, TerraForm gained 521 MW of active wind and solar power plants and more than 8 GW of total pipeline, backlog, and leads. Prior to finalizing the deal, asset valuation was required to determine the worth of First Wind's existing portfolio. Vaisala was selected by SunEdison to deliver the necessary analysis to evaluate key development assets.

Making sure the worth of this portfolio was calculated accurately was highly dependent on robust climate and energy analysis. However, when it came to closing the deal, all parties involved were also working against tight deadlines and needed to act as quickly as possible to complete the financial due diligence for such a major investment. To fulfill these two requirements, SunEdison turned to Vaisala.

"When negotiating such an important and sizeable acquisition, time pressure can be considerable and the ability to act fast can make or break a deal," said Barnaby Olson, Director of Special Projects at SunEdison. "It's nonetheless critical for the success of the investment that early due diligence work is both thorough and comprehensive."

"Having worked with Vaisala 3TIER Services in the past, we were well aware of the team's competency, dedication, and ability to turn work around extremely quickly - and these attributes were invaluable to us as we successfully finalized the purchase of First Wind." 

Vaisala completed analysis on 377.5 MW, or nearly a quarter of First Wind's development portfolio, on an accelerated timeline to accommodate the transaction. This work entailed quality control analysis of available meteorological tower data at the project sites to deliver long-term net production numbers, calibrated to local conditions, with all loss values incorporated (such as, wake deficits, extreme weather, and electrical and grid downtime).

The First Wind acquisition has been characterized as a transformative move to diversify the range of renewable energy projects SunEdison can develop and to aggressively increase its portfolio. Vaisala has carried out asset valuation analysis on both operational and in development wind projects totaling over 30 GW of wind capacity worldwide. 

May 20
Connecting the Dots: Understanding the Value of Improved Forecasts

If you missed the piece we recently contributed to AWEA's "Into the Wind" blog, read on to learn the details ​of​​ Thursday's forecasting session, ​​organized and moderated by Vaisala's Dr. Pascal Storck, at AWEA WINDPOWER.   ​

Screen Shot 2015-05-26 at 9.56.14 AM.png

When considering the tremendous wind energy integration challenges faced by the industry just ten years ago, it is incredible to think where we are today.

The main Texas grid system (ERCOT) regularly sets new wind generation records, sometimes serving up to 40 percent of energy demand, and the New England ISO is currently working to make wind a fully dispatchable power source. Credit for this progress is due to changes in transmission and market structuring, but also in part to major advances in wind power forecasting.

From wind farm operators to system operators, energy schedulers, and marketers, more energy stakeholders rely on wind forecasts for their daily decision-making and power-integration planning than ever before. Widespread adoption and vast improvements in the reliability of forecasting technology have yielded great results.

Yet what remains less clear is where to next focus attention to deliver the best value to the industry. What incremental improvements either currently under development or still to be identified will have the greatest impact on lowering integration costs?

This exact subject will be addressed in one of AWEA WINDPOWER’s sessions (“Connecting the Dots: Understanding the Value of Improved Wind Energy Forecasts,” 9 a.m.), where session chair Dr. Pascal Storck, Global Manager of Energy Services at Vaisala, brings together experts from across the industry, including the U.S. Department of Energy (DOE). Speakers will be presenting their latest research and solutions to a variety of forecasting challenges.

The Mid-Continent System Operator (MISO), ERCOT, and California System Operator (CAISO) markets each have significant wind penetration, and wind is often the price driver for excursions in real-time market pricing. Dr. Craig Collier, Regional Practice Manager of Power Forecasting at DNV-GL, will be sharing a case study that offers a unique way to value wind forecasts and justifies the use of multiple wind forecasts for optimum energy marketing.

Dr. Justin Sharp, Principal at consultancy Sharply Focused LLC, will also be evaluating wind forecast value for operational and market stakeholders based on his years of operational forecast experience, as well as more recent work helping utilities with forecasting trial intercomparisons.

Dr. Branko Kosovic, Renewable Energy Program Manager at NCAR, will focus on scientific advances to forecasting. In partnership with Xcel Energy, NCAR has been exploring and evaluating methods for short-term wind ramp detection, uncertainty, and extreme event forecasting such as icing and snow.

Finally, Joel Cline, Meteorologist and Project Manager at DOE, will update the audience on the current status of the department’s various research projects and future strategy. This will include details from the DOE-funded Wind Forecasting Improvement Project (WFIP2) announced earlier this year, an effort Vaisala and its partners were selected to coordinate to improve forecasting in complex terrain. Mr. Cline will also be introducing an exciting new initiative called Atmosphere to Electrons (A2e) that allows multi-lab, multi-year research for wind characterization.

May 13
Nomad 3 Data Logger Now Launched and Ready for AWEA WINDPOWER

​​Yesterday we announced the launch of our newest product, the Nomad 3 Data Logger®​, which will be on display at AWEA WINDPOWER® next week in Orlando, Florida. The Nomad 3 is a flexible and highly portable device that allows worry-free wind tower data management, making wind measurement easier, more secure, and more economical for developers and operators around the globe.

Early siting and ongoing investment and operational decisions, based largely on the quality of wind resource data, have a direct impact on the long-term success of a wind energy project. However, the task of collecting and storing this data reliably and securely has not always been achieved in a cost-effective manner.

Vaisala Nomad 3 Data Logger

Data loggers currently available to the market can be complex to install and operate, leading to higher costs for training, field time, and additional features typically required for full functionality. They also often fall short when it comes to performance in rough, remote locations and cross-compatibility with the broad range of wind measurement sensors employed across the renewable energy industry.

Furthermore, as the wind energy market expands into increasingly distant and more complex terrain worldwide, the portability and connectivity of data logging equipment for field technicians continues to grow in importance. In both emerging and established markets, it is imperative to reduce the costs and labor involved in data collection and management while maintaining data security and 100% uptime in all weather conditions.

Designed for the Wind Industry

The Nomad 3 Data Logger benefits from Vaisala's unmatched track record for reliability in harsh conditions and decades of in-house wind industry experience, including the introduction of the first viable data logger built specifically for the commercial wind industry back in 1981. 

The new device, however, has been completely re-engineered with the current challenges of developers and operators in mind. It offers technological sophistication while remaining incredibly flexible and straightforward to use. A number of partners and government laboratories have already started using the Nomad 3 as beta clients at locations around the world. These include: NIWE (India's National Institute of Wind Energy formerly known as C-WET), Saiwind, and WISE Information Sentinel.

Product Features: 

  • Compact, light-weight design ideal for sites without road access
  • - Simple installation
  • - Compatibility with all marketing leading wind sensors
  • - Low energy usage
  • - Reliability even in the most challenging environments
  • Linux operating system
  • - Wireless connectivity​ and highly compressed data files
  • - Remote configuration and data management capabilities 
  • - Accessibility from any web-enabled device
  • - Maximum security with data encryption

To test out the new product in-person stop by Booth #4221 at AWEA WINDPOWER in Orlando, May 18 - 21. You can also visit our event page to schedule a meeting and see all the other measurement, assessment, and forecasting news we are presenting at the conference. For more on the Nomad 3, check out the product details page​ or play our promotional game, Searching for Nomad 3, for your chance to wind one of multiple prizes in our drawing. 

May 07
O&M Focus: How Data Drives Decisions

The amount of renewable energy technology deployed over the past 20 years is staggering. Worldwide wind energy capacity reached nearly 370 GW at the end of 2014 according to GWEC and solar power capacity continues to grow at an increbile rate. Recent IHS reports predict solar power may reach as much as 498 GW by 2019.

With a vast amount of equipment now already in operations for several years at projects around the world, the industry has started to greatly expand its focus. The key question is no longer when and where to build the next project, but how to get the most out of project's already online. Attention has shifted from an exclusive focus on development to tackling the challenges of real-time operations.

200318196-001.jpgChief among these challenges are forecasting for energy integration and uncovering performance issues. In both of these cases, it is data that drives decisions and high speed computing is making a major difference in data analysis. Today, advances in time series and spatial analysis as well as the wake models used to estimate wind performance losses are possible because of it

By separating environmental factors from equipment factors, operators can make changes to system operations, maximizing output and even reducing wear and tear on equipment. Combining the power of historical production data, climate data, and mesoscale modeling, it is now possible to benchmark turbine performance and much easier to identify wake effects and other issues at problem turbines for plant optimization. 

As Vaisala's Pascal Storck was recently quoted in an article on this topic by Wind Energy Update, "Wind analysis is finally moving away from the limitations of a laptop, which is allowing a full representation and modeling of the complexities of weather and the quantification of energy uncertainty and risk."​

While the solar industry may not be as mature as the wind industry on the operations and maintenance side, in the last year solar asset management has become a topic of greater focus. To a degree the issues are very similar. You need data to understand and pinpoint the cause of over or underperformance. Was it the weather, an ongoing equipment issue, or a simply lack of maintenance?  However, the solar space requires a somewhat different approach since such a large portion of capacity comes in the form of distributed rooftop generation. For this application, satellite derived solar irradiance time series along with production information provide the most economical solution. 

Recent solar performance studies are helping bring this topic into the spotlight. “Many operators are getting more serious about tracking their plant performance and want an easy way to review their data on a regular basis. Often that will include a software solution, either purchased or built in-house,” said Vaisala's Gwendalyn Bender in an article covering the subject by PV-Insider

April 23
"Visibility" and Solar Power Integration

​​The incredible proliferation of rooftop solar has dramatically changed the power system. Over the past few years, finding the best means of managing this new resource while maintaining grid reliability has been the source of much contention. Yet the catalyst to any real solution boils down to a single word: visibility.

solar rooftop.jpgVisibility of production in the next few minutes to next few days has already been achieved at many large-scale solar projects directly connected to the grid. The task ahead is to gain that same level of predictability for rooftop solar and other forms of distributed generation. ​

“You need to have some idea of what every single solar panel is doing,” said Pascal Storck, Vaisala's Global Manager of Energy Services, who serves on the Solar Power Electric Association's (SEPA) Board of Directors. Next week Pascal will also be co-chairing the Solar Power Integration Workshop​ in San Diego, California where this topic will be discussed at length following the popular Utility Solar Conference. ​

Professionals from across the industry will be presenting on the technological, financial, and regulatory solutions to gaining true visibility and the complex issues that this brings to the table. Speakers include experts from NREL (the National Renewable Energy Laboratory), EPRI (Electric Power Research Institute), SMUD (Sacramento Municipal Utility District), San Diego Gas & Electric, and HECO (Hawaiian Electric Company).

April 16
Reuters Covers Impact of U.S. Wind Anomaly in California & Texas

​Today Nichola Groom of Reuters referenced Vaisala's recent U.S. Q1 wind analysis in a story covering the extreme low wind event and the associated impact it had on the power grids of California and Texas as well as several West Coast utilites.cali_wind.jpg

According to her article, titled Warm winter temperatures slammed California wind farms, the low wind conditions caused a 50% drop in wind power output for Southern California Edison, a 10% drop for San Diego Gas & Electric, and a 14% drop for Texas as a whole.

As wind power penetration continues to grow across the country, it will become continually more critical to mitigate the risks of low wind events like this one. Today there are already mechanisms in place that can help the energy industry protect itself through portfolio diversification and wind hedges that take full advantage of robust climate datasets.

Click here to read the full article in Reuters.

April 08
Off the Chart Low Wind Anomalies Hamper Projects Across U.S. in Q1 2015

​As recently reported by North American Windpower​ and Recharge, extremely low wind conditions in the first quarter of the year across much of the United States have caused low generation at numerous wind farms and a great deal of concern about future performance.

Vaisala's analysis and Q1 U.S. Wind Performance maps, which were discussed in both stories, capture and confirm these observations. Our climate scientists have been tracking and analyzing the event through our continually updated historical database and have flagged several extreme anomalies, particularly in the West. 


In January, nearly all states west of the Rocky Mountains experienced wind speeds at least 20% below their long-term monthly average, which is usually the lowest extent we show in our studies. However, within that same month some areas saw wind speeds nearly 50% below average, effectively "breaking" our typical ​scale. ​

Widespread low performance continued to a lesser extreme in February, but returned strongly in March with a vast majority of the country seeing wind speed anomalies 20% or more below normal. Popular wind regions like Texas, California, and parts of the Midwest were particularly hard hit given their large concentration of operating wind assets. After completing a more thorough rank analysis, Vaisala uncovered that most of Texas and California experienced the lowest wind speeds of any first quarter within the entire historical record - some 47 years.


An anomaly of this magnitude covering such a large area has clearly caused a great deal of alarm amongst operators, some of whom generated less than half the energy they produced last year during the same time period. Many are asking themselves, "How could something like this happen?"

Our investigation has identified a low wind pattern across the U.S. with a large blocking high pressure system over much of the West. The polar jet stream was also much further north compared to last year. This resulted in above normal wind speeds in central Canada and some border states and a mild winter in much of the West. Weak surface pressure gradients and light southerly winds in March were particularly challenging to many projects across Texas.

Without a doubt a low wind event can be worrying, and Vaisala is working closely with clients to evaluate what it means for the future. While a tentative outlook for Q2 2015 indicates a return to more typical conditions, incidents like this underscore the importance of having a long-term perspective on wind variability, both for operating and pre-construction projects.

Operators must understand the cause of a project's over or underperformance and reconcile it against long-term conditions at a location. For investors it is particularly critical to understand long-term climate and weather patterns at a proposed site (both in terms of extreme highs and extreme lows) when drawing conclusions about future performance based on past observations.  

To download high-resolution versions of our analysis, please see the ​quarterly map here and the monthly maps here

April 01
The Effects of Extreme Weather on 2014 US Solar Performance

​Every day we hear about major weather events happening both locally and globally, but we typically only think about them from a short-term point of view. We understand that rain may ruin our plans to take the kids to the park or that a snow storm could mean a flight cancellation and not making it to an important meeting. We understand even more directly the effects of weather events in renewable energy where they can either boost or reduce our plant's performance.

But, how do we know when the weather we are experiencing is truly out of the ordinary or just a part of regular climate cycles and variability? How do we know when what is occuring is a once in every 20 year event or something we can expect more often over the long-term?

​Today Vaisala released the 2014 U.S. Solar Performance Maps, which illustrate the impact of both annual and short-term, month-to-month weather variations on performance at U.S. solar projects while placing them into a long-term context. This study reveals frequent and significant deviations from long-term average irradiance conditions over the course of the year and helps operators to better analyze the effect of solar resource variability on both over and underperformance.


In terms of short-term solar operations, routinely evaluating resource variability is critical for understanding whether a project is performing as it should be, based on the available resource. This allows both distributed and utility-scale generators to effectively deploy maintenance and repair crews when problems, such as inverter issues or heavy snow on panels, lower production when resource data clearly show the sun was shining. ​

Vaisala's anomaly analysis is also crucial for viewing recent performance from a long-term perspective. It allows operators to understand whether recent conditions (low or high irradiance, heavy snowfall, etc.) foretell what can be expected throughout a project's lifetime or if it is out of the ordinary. ​

From an annual perspective, this year's weather patterns had an adverse effect on a large number of installations along the Atlantic Coast from Florida to Massachusetts, as well as Texas, which experienced up to 5% lower than average solar irradiance. 

The bulk of projects in California and the Southwest saw an uptick in solar irradiance that may have increased overall 2014 production at many sites. However, these annual variations only offer a high-level view of project performance and don't tell the entire story. Vaisala's monthly analysis gives a much more robust understanding of how specific weather conditions affected solar production throughout the year. ​Click here to view the monthly maps and read more. 

The summer of 2014, for instance, was the coolest summer since 2009 and the ninth wettest summer on record within the continental U.S., with cloudy conditions leading to below average solar irradiance. This meant underwhelming solar performance in many regions where there are large numbers of operating projects, and negative media attention for solar projects recently put online – such as Ivanpah, Agua Caliente, Solana, and Topaz. 


In this aerial photo, downtown Dallas is enveloped in morning fog, Tuesday, Dec. 9, 2014. (AP Photo/Mike Alvstad)                       

While the summer was disappointing, it was not the only or the most extreme anomaly of 2014. January, October, and December also saw atypical conditions where solar irradiance was more than 10% above or below average for much of the country. In Texas, where there is growing interest in solar and already a few operational projects, extremely foggy conditions this past December created striking photos like the one above of the Dallas skyline emerging from the thick haze. The unusual weather anomaly also caused extraordinarily low solar irradiance that month compared to previous years.

This week our 2014 Solar Performance Study will be discussed at the Solar Asset Management North America​ conference in San Francisco where the impacts of weather variability on operations, maintenance, and finance will be a topic of conversation

March 19
Why Solar Variability Matters - Germany's Eclipse and Power Integration

Rare or extreme weather events are​ much in the media these days, and variability is now of particular interest since an ever increasing amount of our energy supply is fueled by it. ​

Take, for example, the current panic in the news over the March 20th solar eclipse and its projected impact on solar power generation in Germany, a country that receives roughly a third of its power from renewable energy, including 1.4 million solar energy systems (almost a quarter of all installed solar capacity on Earth).

shutterstock_44559820.jpgWith the moon set to block out part or all of the sun over a roughly four-hour period, some have estimated a potential drop of 30 GW of solar power production across Europe. In Germany solar power could drop 2.7 times faster than it normally ever does, a rate comparable to shutting down 200 MW of power every minute for 40 minutes.

The German grid will experience its first major stress test to cope with the situation and most feel that they are prepared for it. Major solar plants will be disconnected from the grid and back-up power is scheduled. A majority of the power loss projections are also based on clear sky conditions, which in Germany in March aren't guaranteed. Some experts say weather variability and cloud movement will have a larger impact on power than the eclipse and this is something the German grid has already learned to deal with on a daily basis.

While tomorrow we will know whether Germany's careful planning mitigated the predicted "catastrophy" of the eclipse, normal weather variability and its affect on renewable energy remains a source of anxiety for utilities and grid operators around the world. However, while the challenge is certainly there, changes in market structuring along with weather and power forecasting have made it possible to safely and effectively integrate larger penetrations of renewable energy than previously imagined just ten years ago. With the skilled forecasting technology that exists today (and continues to improve each year), providers like Vaisala alleviate much of the concern over reliable grid operations when integrating renewable power sources.

Understanding variability is just as important in the pre-construction phase of project and grid planning as it is in the operational phase. In ​today's Solar Speaks podcast​ with Kathie Zipp of Solar Power World, Vaisala expert, Gwendalyn Bender, explains why site assessment is so important in planning any solar project and exactly what to look for. She even touches on why developers and operators of the notable Ivanpah solar project weren't as concerned as the media when the project didn't perform as hoped its first summer. Listen to learn more.

March 12
UAE Wind Atlas from Vaisala and Masdar to Inform Middle East Wind Development

​Earlier this week we announced the public launch of our UAE Wind Atlas, created in partnership with the Masdar Institute. This highly significant investment and infrastructure planning tool is now freely available through the International Renewable Energy Agency's (IRENA) Global Atlas.

As the United Arab Emirates (UAE) seeks to satisfy domestic energy demand by diversifying its oil-rich energy portfolio, progressive economic policies and a supportive stance on renewable energy look set to make the country a leader within the region. While, as a desert nation, the UAE is primarily recognized for its strong solar potential, wind energy will play an important role in broadening the range of renewable energy sources and providing security of supply when solar energy falls short, such as during night time hours. 


​Given the variable nature of wind generation, siting and integrating high penetrations of wind energy pose unique challenges. Bringing online large volumes of wind power in a cost-effective manner demands the formation of comprehensive energy policies and infrastructure plans.

These, in turn, require a detailed understanding of available wind resources and their variability over time and space. To fill this crucial information gap, the Masdar Institute naturally sought Vaisala's advanced wind analysis capabilities and extensive experience in large-scale renewable energy mapping efforts. Vaisala was the first to map worldwide wind and solar resources at high-resolution and over the past 10 years has conducted further large-scale resource planning and integration studies in over 20 countries. 

Masdar sees the UAE Wind Atlas as a mission critical tool for evaluating the country's potential, particularly due to wind's unique characteristics as a resource. "Wind information has to be generated at a number of heights and a whole altitude profile needs to be produced as different turbine technologies work at different heights," said Director Hosni Ghedira of the Masdar Institute. "Also, unlike solar, wind can vary significantly across short distances so high-resolution spatial information is vital." 

With 10 years of hourly meteorological data at multiple heights and a spatial resolution of 500-meters, the wind atlas developed by Vaisala and the Masdar Institute provides a comprehensive view of the UAE's wind resource to support wind energy investment decisions. 

Adnan Z. Amin, Director-General of IRENA, said, "The launch of the UAE Wind Atlas marks another key milestone in our efforts to bring a comprehensive clean energy resource map to the global community. The support provided by Masdar Institute's Research Centre for Renewable Energy Mapping and Assessment and Vaisala has been critical to help developers of clean energy projects find valuable information to assist in their investment decisions."​

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 About News and Insights

This page helps you stay updated on Vaisala's latest news, research, and opinions on current energy industry trends and challenges. Get guidance and insights directly from our experts in weather measurement, energy assessment, power forecasting, and asset management. ​