When I first invested in CPV I was impressed with both the concept and the potential for both energy saving and emissions avoidance. The tech is definitely clever, and the world desperately needs clever tech if we are to turn around a carbon based economy into one that relies almost exclusively on renewables. I have been a green activist since 1973 when it was just a vague hippy hope, and when only people in the sciences field like myself had any clue what the term "global warming” was going to mean.
However as I have watched my early gains in CPV turn to losses I have seen the
gradual repositioning of the product concept from initially being promoted as a significant power generator to being not much more than a battery charger for smart window / smart home devices. That is nice but it is not going to save the planet.
The more the prototype became attuned to the needs of the building industry the more the limitations of the tech became apparent. It is still a good idea and will no doubt find its own place among a growing set of solutions,
but it is not what it was initially promised to be, and I now doubt if it will prove to be significantly economically attractive.
The maths on this will always have to do with the economic cost/benefit of having an IGU that generates a small amount of power vs the economics of one that does not. This is going to end up being a simple calculation, but the full set of considerations of cost/benefit will have to be understood and factored in by the specifier before doing that simple calculation.
As I have said previously here there is a real and definable cost that comes from rejecting (i.e. by using it to produce electricity) all of the IR solar gain from entering a building. In a cooler climate (think Europe, Canada, USA, NZ, China, Japan) that may limit its overall cost benefit, because by excluding winter solar gain the owner will have to pay to provide an equivalent quantum of grid-priced electric heating to make up for it. Because the amount of power generated by the photovoltaics can never be as high as the amount required to raise the building interior temperature by the amount of (free) heating that was rejected, there will be a trade-off. Under some conditions it may be small, and not unduly unfavourable, in others it will be uneconomical, representing a net loss and net cost to the system rather than a net gain and a net saving. In a hot climate the calculations are somewhat different in that the rejection of heat ingress can often be a positive value and adds to the reduced cost of cooling. In a hot climate IR rejection will most of the time be a net economic gain. But these differences need to be understood to do the sums. It's not rocket science.
The additional costs of the overall technology differences required by the CPV design, over and above the full cost of installing a “standard” commercial low e glass triple glazed equivalent window, represent the premium required to buy all of the convenience features provided by the CPV system, along with the value of any actual net power savings over the lifetime of both units. Again these are not necessarily difficult calculations to perform, but they have to be performed to get the comparison.
Currently CPV seems promising only in a situation wherein we do not know the actual installed costs, nor the actual standardised net power generation and net power savings, nor the other net benefits from one system option vs the other. My concern has been that as the realistic performance and realistic installed costs become clearer the economic advantage may not end up being worth the effort in many cases. Chippy’s overhyped and rather fanciful goldmine predictions notwithstanding! With the latest panel size showing a significant reduction in power generation relative to the increased installed window area this seems to be going further towards the lower economic benefit end of the calculation. So for now at least I’m out. You can all take comfort in being serenaded into millionaire status by CPV’s self-appointed resident barking gate keeper and cheer leader. GLTAH!