By Michael Humphreys, special to Solar Power World
A large solar thermal installation in a hot climate had PTRVs (pressure and temperature relief valves) installed on the hot outlet of each bank of collectors. Manufacturers could have communicated why PTRVs were unnecessary and a hindrance in this scenario.
When a solar thermal system fails to deliver, the solar panel manufacturer typically carries the burden of complaints. While the system is comprised of a range of components– pumps, valves, tanks, controls–the collectors are often seen as the heart (and brand) of the system. As solar panel manufacturers, we should endeavor to ensure accountability of the system as a whole.
Over the years, my team has encountered many concerns regarding system performance and failure. While some were genuine issues related to the solar collector, the vast majority were design and installation flaws. Some familiar examples of installation issues are undersized expansion tanks, pressure and temperature relief valves installed too near the collectors, low temperature rated components, misplaced temperature sensors and structurally flawed mounting structures.
As manufacturers, our focus is to produce and sell quality products. Our businesses are based on quality. But when we are also blamed for the failure of improperly installed systems, how much responsibility do we assume to ensure quality installations? Of course, we have installation manuals and training sessions, but we can’t guarantee that they are read or attended by every installer.
My take is that a manufacturer, or a representative of one, must remain in open communication with installers. The responsibility of ensuring quality projects is a two-way street, whereby manufacturers should actively ask questions in addition to answering them. This helps ensure that a designing engineer and contractor have a sound understanding of the solar thermal system. This is especially true of HVAC professionals who have little or no experience with solar thermal, regardless of their overall hot water experience. Too often solar thermal systems are installed using standard HVAC components and design conventions, which are not always suitable for the much higher temperatures that solar systems can experience.
Let me offer an example. A large solar thermal installation in a hot climate had PTRVs (pressure and temperature relief valves) installed on the hot outlet of each bank of collectors. This was in addition to a seriously undersized expansion tank. The result was a system that would dump heat-transfer fluid each time the system reached a high operating temperature. The system owners were forced to shut the system down until changes could be made.
The PTRVs were not designed for solar thermal applications, but traditional practices require them for safety. We had no involvement in the design of this system, but if we had, we could have communicated why PTRVs were unnecessary and a hindrance in this scenario.
Who is responsible for the poor design of this system? I would suggest that I am. I failed to ensure that distribution channels knew that we offer–and highly recommend–free system design review services.
The reality is that my team does have involvement in most projects, and so most are designed correctly and perform well. The communication between the manufacturer, designer and installer is crucial. Contractors with experience in solar thermal don’t require oversight for every project, but still appreciate a quick review of their designs. It is those few cases where a general contractor has won a bid-spec product and we are not engaged to review the design where issues arise, giving the solar industry and its brands a bad reputation.
So for the sake of the industry and our brands, let’s take responsibility for how our products are implemented by reviewing system designs where possible before rudimentary mistakes are made.
It will certainly save some of the lost time and money that dealing with failed projects can cause. SPW
Michael Humphreys is the founder and CEO of Apricus Solar, a manufacturer and integrator of solar thermal systems globally.