A possible game-changer for PV and SHW

Is the day approaching when the cost of PV will beat the cost of thermal collectors?

We see press releases and claims about the wonders of new products all the time but this week I saw a new product that has some fascinating ramifications.

At the German uber-solar conference Intersolar, which is on right now, Refusol launched a new product: the PV Heating Solution. Simply described, it's a control system and heating element that uses PV to heat water instead of thermal solar panels.

Refusol, which was recently purchased by Advanced Energy, has a pretty impressive capacity and track record and is now ranked as the fourth largest inverter manufacturer in the world, so one assumes they have some bright sparks there. If it has this right, the implications for the solar thermal industry are huge – can PV beat solar thermal in cost, complexity and performance? 

That remains to be seen (and Refusol/Advanced Energy are not a client, nor did they ask me to publish this by the way).

For some years I have speculated with colleagues (who know far more about thermodynamics than me) that the day was approaching when the cost of PV would beat the cost of thermal collectors. However, what we know is that heating water takes a lot of energy (1 kcal to heat 1 kg of water 1 degree Celsius). Having a quick browse around a number of sites suggested that most 2-3 person homes use around 12-15kWh per day to heat their hot water using electricity depending on various efficiencies etc. That's why electric water heaters completely suck.

For reference, a typical Solar Hot Water system produces around 7-10kWh/day.

Although information is limited so far, what the information on Refusol’s new product does say is that the system is designed for between 3-9 panels. If we assume 300W panels at 4PSH, that's between 3.60kWh/day and 10.8kWh day.

So on the surface at least, assuming you used nine PV panels, you would get close to the same daily energy production as Solar Hot Water would with two or three thermal collectors.

As readers would know, I love the idea of technological convergence and have watched with great interest and enthusiasm as products like Solimpeks Hybrid (PV Thermal) panels rapidly gain market share in Australia. Installers, retailers and customers alike just love the idea of a single, good looking system that is multi functional and the results of real world testing are excellent.

PV panels are cheap today – perhaps about the same as solar hot water collectors (which are pretty damn simple and made in high volume) – but not, I would suggest, one-third of the cost (yet).

What is interesting about the solution however, is that it is simple to install; plug in wires instead of plumbing and pipes. It could be used as a simple retrofit to an existing electric tank. PV efficiency is going up and cost is coming down. And of course, it can generate electricity for other uses in the home too.

Perhaps most interestingly, in markets like Australia where there is little, if any value put on exported PV energy, energy storage is the holy grail. So why not store PV energy as heat instead of power? Now that starts to get interesting.

It takes more space at the moment and using electricity, even if it’s generated with PV (instead of the sun’s thermal energy), has traditionally been less efficient, but it may just be that Refusol has come to some conclusions that the other benefits are here, now.

Nigel Morris is the director of Solar Business Services.

This article was originally published by SolarBusinessServices. Republished with permission.

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