Solar maps underline sun’s variability as fuel source

New solar performance maps released by 3TIER, a global leader in renewable energy information services, underline the need to look beyond the ‘it’s always sunny here’ mentality when deciding to go solar. The maps illustrate how solar irradiance varied from its normal monthly averages across the US from June to August of this year. Indeed, the variances were quite significant, often in excess of plus or minus 20 per cent of normal. The company explains why this is significant:

The maps dispel a popular perception that solar energy is relatively consistent from year to year and underscore the need for thorough resources assessments prior to investing in solar projects. Variances in solar irradiance, which are caused by short-term weather anomalies, have a significant impact on the long-term economic viability of both distributed and utility-scale solar power development.

In June, record-breaking heat in Delaware, New Jersey and North Carolina skewed normal sunshine forecasts, while record-breaking precipitation was recorded in Michigan and near record-breaking rainfall was experienced in Iowa, Illinois and Nebraska. All of these brought with them cloud cover.

In July, Hurricane Alex and Tropical Storm Bonnie reduced irradiance in Texas and the Midwest, and a persistent marine layer all month resulted in below-average irradiance in coastal California.

In August, higher temperatures combined with higher-than-average atmospheric water vapor content in the southeast, producing unusually high cloudiness and rainfall, which pushed irradiance below its monthly mean. And parts of Montana had above average rainfall and cloudiness. The California coast had persistent morning fog.

Kenneth Westrick, founder and chief executive of 3TIER, said these variances will become increasingly important as solar energy is expected to develop on its own merits:

Solar power development in the US is driven more by government incentives than production potential right now. However, as the industry  matures and policy becomes more performance oriented, projects will be more rigorously scrutinsied for their long-term potential.

All of this may well be bad news for the solar industry, which is already under pressure. One of the issues it is facing is that the economic downtown has meant many projects are having difficulties being shovel-ready by December 31 2010, the deadline to receive millions of dollars in government stimulus money. To be eligible for the tax credit or grant provided under the Obama administration’s stimulus plan, companies must have spent 5 per cent of their projected construction cost by that deadline.

An added burden for those companies operating in California is Proposition 23, a measure on the ballot to be voted on by Californians in the November 2 midterm election. If approved, it  would delay implementation of carbon regulations until the state’s unemployment rate falls to 5.5 per cent and stays that way for a year. It is now 12.4 per cent.

Rolling back that carbon legislation would remove a key incentive to go solar that has been driving massive investments in the sector.

Dario Frommer, a partner in Mayer Brown’s Los Angeles office who was a co-author of the original legislation in 2006 and follows it closely for a number of clients, said the question California is grappling with is “do we go it alone?” There is no national carbon legislation, the country is only slowly coming out of recession and unemployment remains high. All of this, he says, has given opponents of AB 32 (the California carbon legislation) ammunition to slow it down.

Lynn Jurich, president of SunRun, one of the leading residential solar companies in California, believes the uncertainty over where California is going is a blow for investment in clean technology, noting that when there is not certainty, funding gets a lot more expensive. If the proposition passes, she believes solar development will be confined to a niche market in the US.

Are we going to be the ones creating green economy technology, or are we going to be importing it?

That is a question that has yet to be answered. But 3Tier’s maps, which is what got me onto solar in the first place, do give one pause for thought about solar’s reliability given the wide variances in weather. For even sunny California, the maps show, do have cloudy days.

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