Automate Power Management and Demand Reduction Using The Solar Load Controller

Industrial and business power consumers have steadily increased their use of solar energy to control costs through demand shedding.  Although this method is useful, its potential is often not fully realized because demand reduction can be compromised locally when the sun is not shining (e.g., by transient clouds).  Traditionally, the economics behind solar PV power generation are penalized as power output is dependent upon the weather and the other factors, so loads were not easily controlled or dispatched to meet certain load requirements.  On the customer side of an electric meter, large electrical users usually pay for both the energy they use (kWh) and their demand (kW).  The Solar Load Controller (SLC) addresses these problems, providing a way to enhance the economic feasibility of solar PV power generation by increasing the “effective capacity” through minimal, selective control of the load. 

The SLC reduces load when needed by acting on the end use settings of grid-connected photovoltaic energy systems and appliances through the modification of operating thresholds and/or operating schedules in order to maximize the coincidence between localized or regional peak load requirements (demand) and the output of solar or other renewable power plants (supply), while minimizing disruption to the facility user.  The result is that the end user realizes the maximum benefit by adapting their power use to the availability of solar power generation, while also avoiding costly peak demand tariffs on grid power.

Solar Load Control Diagram

Potential Applications

  • Intelligent PV thermostat - receives logic driven signals to adjust user set temperature upward or downward depending on the SLC logics decision.
  • Software for monitoring and control of grid connected advanced rechargeable energy storage systems using solar PV; multiple platforms and configurations possible.

Competitive Advantages

  • The value of the SLC far exceeds the cost.
  • This cost recovery is continuous for the life of the installed PV system panels (typically 20 – 30 years)
  • The SLC may add up to $500 of value per installed kW of PV capacity, in effect a 10% reduction in the cost of a commercially sited PV power plant.

Technology Description

The Solar Load Controller allows the building management system to either reduce total consumption or shunt operations which draw heavily on their resources to stay under peak demand and avoid demand tariffs.  The SLC works by reacting to the availability of solar energy, measuring the total output of the solar generation system and using patented techniques to compare the output of solar cells to loading factors which are typical of the equipment in the building. This creates a system plan to which the building’s power resources are adjusted before going over the peak power usage for the billing period, thereby avoiding peak demand tariffs.  Through the use of patented techniques the availability signal is analyzed and processed to create a dynamically determined expected peak load which is then used to modify the operating thresholds or schedules of grid connected photovoltaic energy systems or appliances.

Stage of Development

This invention has been extensively developed by Dr. Richard Perez in the Atmospheric Sciences Research Center at the University at Albany, SUNY.  The SLC is the subject of three issued U.S. patents:
US 6,037,758
US 6,542,791
US 6,889,122

For More Information Please Contact:
Peter Gonczlik
Office for Innovation Development and Commercialization
University at Albany, SUNY
ES 244
1400 Washington Avenue
Albany, NY  12222
(518) 442-3270