Helpful? 1

Solar thermal doesn't seem dead when I read about this:

I keep seeing it mentioned here in blog posts, etc, that solar thermal is dead. Just use PV and electric water heat. Okay, makes enough sense. But then I came across Solaris when it was mentioned in one of the comments of a blog post (http://www.solar-hot-water.ca/).

After speaking with Bruce, their rep, it seems their product (SunPump) is relatively new, and just passed some testing standards in Canada (they're based in BC). But, it seems like quite the silver bullet. Their product is pretty much all-in-one, and relatively simple. Refrigerant gets circulated through the solar panels, grabbing heat for DHW and hydronic heat (hydronic wall heaters available through them separately). I've seen mentioned a COP of 7 in sunlight. Works all winter long (to -15C, so might be no good in extreme climates), and has electric backup. And since it's a heat pump, it's reversible, meaning that the system can be used to COOL hydronically as well. Even at night (the panels basically act as a radiator at night, effectively turning it into an air source heat pump (I think I have the physics right on that)). Oh yeah, and they're working on a version with PV mounted to the same panel, saving space but also increasing the PV efficiency, since those panels like cooler temps. This seems like a no-brainer for a (nearly) PH project I'm considering.

Has anybody come across these guys before? At a show, conference, etc.? This product gets me all warm and fuzzy, and I'm wondering why nobody's talking about it?

(See http://www.solar-hot-water.ca/wp-content/uploads/SunPump-brochure_Feb15d... for a brochure; http://www.cbj.ca/mobile/business_in_action/nov_13/solaris.html for a periodical that wrote an article about them)

Asked by jonathan nagar
Posted Thu, 03/06/2014 - 21:08
Edited Thu, 03/06/2014 - 21:13

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2 Answers

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1.
Helpful? 0

Jonathan,
I look forward to hearing from any GBA readers who have direct experience with this technology -- preferably, someone who is not employed by Solaris or one of the company's distributors.

This system sounds fairly complex when compared to a simple Mitsubishi or Fujitsu ductless minisplit paired with a photovoltaic array. Whenever you add complexity to a system -- and whenever you depend on a single company for proprietary technology and future maintenance services -- you need to have monumental efficiency improvements to overcome the inherent disadvantages of complexity (and one's dependence on a new start-up company).

Perhaps Solaris can provide evidence of such monumental efficiency improvements; but I'll remain skeptical until I see a few years of field reports.

Answered by Martin Holladay, GBA Advisor
Posted Fri, 03/07/2014 - 08:18

2.
Helpful? 0

It is fairly complex, but since it can operate at temperatures well below ambient, it is super-efficient during the daylight hours as an unglazed solar collector, and probably averages better than 80% solar efficiency during the day when most of the heat uptake happens

At night it'll be a much lower efficiency- soaking up the radiated moon-beams & star light would be efficient but negligible, with most of the night-time heat coming from the direct heat exchange from the ambient air, in much lower quantity & efficiency than a mini-split coil.

And I'm sure efficiency sucks big-time with 2' of snow on the roof, with a less efficient defrost cycle that a mini-split too.

Still, standard production silicon PV runs about 15% efficiency from sun-to-DC, and with inverter losses more like 12-13% sun-to-AC. Assuming you can get a COP of 3 out of a mini-split a PV to DC to AC to room heat BTUs is at best 40%, about the same efficiency of a standard flat glazed thermal panel, or about half the solar-uptake efficiency (maybe even less) of an R410-refrigerant unglazed solar panel, which is roughly what they're alleging in their brochure, interpreting their "Area Cost" numbers:

http://www.solar-hot-water.ca/wp-content/uploads/SunPump-brochure_Feb15d...

So in climates where rooftop snow loads are small & fleeting it's likely that the average performance would edge out a mini-split solution, and even non-superinsulated homes might have enough roof area to cover most of their thermal energy use with it, given a big enough buffer tank to cover the peak space heating loads during low-sun days.

Whether it can be installed at a sufficiently low price to be competitive with a PV/ductless solution remains to be seen, and the reliability issues are open questions. The fact that it's only available as a $0 down lease option may give you some amount of protection on the down side if the company goes bust or the system is unreliable or doesn't perform. Buying it outright would probably carry more risk than all but the true-believers would sign up for which is probably why they're marketing it that way. I suspect that the first few hundred installations will be pretty much beta-test sites, and there will be a lot of on-site involved as they discover and iron-out performance & reliability issues.

Answered by Dana Dorsett
Posted Fri, 03/07/2014 - 15:32

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