I see a stronger redundancy by using disparate overall approaches of technology. This is an overall philosophy. I will try to describe the overall weakness I se

I see a stronger redundancy by using disparate overall approaches of technology. This is an overall philosophy. I will try to describe the overall weakness I see using the same approach for a redundant system. A double PV system I see as too homogeneous and thus susceptible to the same risks. A PV system with a solar thermal system for redundant heating I see as more diverse and thus resilient. I try to design to a 100 year expectation. We all know that PV systems need replacement on a schedule. We also all experience electronic digital systems that may meet are needs but are no longer supported. I see this currently as a complexity that we accept because the tech is so darn convent. Solar thermal can take many forms from very passive to a combination of almost passive with the exception of fluid moving systems. The fluid moving systems components are not nearly as specialized as the PV components and thus the overall system is more malleable. This malleability provides for greater variation in replacement parts and short term hacks to get through system failures.