Energy blogs

  • Dc
    11 Sep 2014 - 15:15 by Dc
    Smart homes have promise but require manufacturers to pay attention to quality and consumer driven issues. Read more about what goes into developing products for the smart home here:
    Join the discussion about smart homes below.
  • Dc
    9 Sep 2014 - 14:10 by Dc

    The new version of PVWatts released in September 2014 represents a major update to both the online web tool interface and the underlying algorithms. Compared with PVWatts Version 1, our new update will predict roughly 7-9% greater energy output for a fixed tilt system given similar assumptions. The new results much more closely match measured system performance data, and address concerns that PVWatts Version 1 tended to under-predict PV system performance given the default input assumptions. The key changes in this new version are listed below:

    • Losses We’ve switched from derate factors to system loss percentages. The default value for system losses is 14%. Note that this value does not include the inverter performance.
    • Inverters Inverter efficiency is entered as a separate input. The default value is 96%. The underlying inverter model also has been revised to represent the performance of modern commercially available inverters.
    • Modules You can select between three different module types: Standard, Premium, and Thin-Film. These can help consider different module technology options in a generic way.
    • Trackers One axis tracking systems account for self-shading of one row to the next, or can be operated in a backtracking mode. Row spacing can be adjusted by setting the ground coverage ratio (GCR).
    • Sizing System sizing is explicitly handled by the new DC-to-AC Size Ratio input. This allows you to consider different system sizing strategies and operational effects such as clipping. The default value is 1.1.

    By default, PVWatts retains the NREL NSRDB 1961-1990 TMY2 dataset as the default option. However, you can select to use NREL NSRDB 1991-2005 TMY3 data or the satellite-based 10-km gridded SolarAnywhere data.

    For more information on these changes, please consult the new online help system, where you will find a link to a detailed technical reference manual that explains all of the equations and assumptions used in the model.

    We hope you enjoy using the new PVWatts!

    The NREL PVWatts Team.

  • WikiSysop
    4 Sep 2014 - 16:40 by WikiSysop
    Human energy can be considered a type of renewable energy. Science News reports on how children's brains use almost half of the energy their bodies consume. Read the full story here:
  • WikiSysop
    1 Sep 2014 - 18:34 by WikiSysop

    Bioenergy: America's Energy Future is a short documentary film showcasing examples of bioenergy innovations across the biomass supply chain and the United States. The film highlights a few stories of individuals and companies who are passionate about achieving the promise of biofuels and addressing the challenges of developing a thriving bioeconomy. This outreach product supports media initiatives to expand the public’s understanding of the bioenergy industry and sustainable transportation and was developed by the U.S. Department of Energy Bioenergy Technologies Office (BETO), Oak Ridge National Laboratory, Green Focus Films, and BCS, Incorporated.
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  • WikiSysop
    22 Aug 2014 - 11:12 by WikiSysop

    The city of Knoxville is in the running for a $5 million prize that could be applied to public and community efforts to reduce energy consumption. Watch the video about this in the link below, then post comments, suggestions, questions, etc. as a response to this post.

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