SunTrac Challenges Solar-Assisted Air Conditioner Patent

  • SunTrac Solar Manufacturing LLC has challenged at patent owned by DZSolar Ltd. that is directed to a solar-assisted temperature control system.
  • SunTrac alleges that the invention claimed by DZSolar was disclosed in another patent application at least 16 years before DZSolar filed its patent application. If SunTrac is successful in the challenge, the DZSolar patent would be canceled.

SunTrac Solar Manufacturing LLC, a producer of hybrid climate control systems based in Tempe, Arizona, filed a challenge last month against a patent owned by the U.K.-based DZSolar Ltd. SunTrac’s challenge was brought before the Patent Trial and Appeal Board of the U.S. Patent and Trademark Office, and alleges that the claimed invention of DZSolar’s U.S. Patent No. 9,267,713 is unpatentable because the invention was already well-known at the time DZSolar filed its patent application. In order to be eligible for a patent, a patent application must claim an invention that is a new and non-obvious improvement over existing technology at the time the patent application is filed.

The 713 Patent is directed to a “temperature control system” having an evaporator, a compressor, a thermal collector, and a condenser as shown below in an annotated Figure 1 from the patent:

The 713 Patent acknowledges that closed-loop refrigeration systems having an evaporator, compressor, and condenser were well known in the field of temperature control systems. The patent alleges that the addition of a thermal collector to the system is inventive. The thermal collector is “configured for utilizing an external heat source to increase the temperature of the refrigerant within the circuit.”

Conceptually, the 713 Patent appears to claim a solar-assisted air conditioner. As refrigerant is circulated through a closed-loop refrigeration system, the compressor consumes energy and compresses the refrigerant (in gas phase) to a higher pressure. By also heating the refrigerant with solar-generated heat to expand and thus raise the pressure of the refrigerant, a solar-assisted air conditioner reduces the amount of energy consumed by the compressor to achieve an equal increase in refrigerant pressure. Solar-assisted air conditioners can therefore improve the efficiency of a closed-loop refrigeration system.

In challenging the 713 Patent, SunTrac argues that the invention claimed in the patent was known in the field of temperature control systems at least 16 years before DZSolar’s patent application was filed. SunTrac points to an earlier patent application by an inventor named Paris Melidis that allegedly describes a solar-assisted air conditioner similar to the one claimed in the 713 Patent, namely a temperature control system having an evaporator, a compressor, a thermal collector, and a condenser. SunTrac annotates a figure from the Melidis patent to show various components of the system:

If SunTrac can demonstrate a reasonable likelihood that it can prevail in the case, the Board will institute a trial to determine whether the 713 Patent should be canceled for claiming an unpatentable invention. Before the Board reviews SunTrac’s challenge, however, patent owner DZSolar will have an opportunity to respond.

Based on publicly-available records, the 713 Patent does not appear to have been previously litigated and there is no apparent dispute between the parties. SunTrac’s challenge is therefore one of the rare cases brought before the Board without underlying litigation; studies have estimated that just 10-15% of all challenges before the Board fall into this category.