[Greenbuilding] Water heater timer energy savings?

[Antonioli Dan]

Nick, 

I looked into some of the systems you suggest and they aren’t as cost effective as you might think. There’s even a newish system out of New Zeland that uses a combination of solar and condensation to produce hot water under any weather conditions, but it’s not cheap! I think the day will come when the efficiency of heat-pump electric hot water heaters, the efficiency of pv, and the lowering price of pv will make these systems cost competitive with solar thermal. 

In the meantime, I already have a garage full of 4x10 flate plate collectors in good condition and am using them for different projects, including a stellar thermosyphon system on my rural property that cranks out a ton of hot water. 

Thermal collectors are also much more efficient than pv, and a good thermal system can also be married to a hydronic heating system, as well as air handlers to be incorporated into existing hvac systems. We installed a multi-system in San Francisco where the old hvac beast was removed and replaced with an air handler and high efficiency solar gas boiler. It was heated or “pre-heated” by solar thermal, provided all the hot water needs of the house, hot air into the existing hvac, and a single low-temp baseboard heater for one of the bedrooms which was in the basement and cold year-round….it works like a charm and the owners are happy with it. 

I wouldn’t regard Solarhart’s standing as reflecting the solar thermal industry. All major hot water heater companies offer solar thermal packages so along with PV solar thermal has gone much more mainstream. And in the US people don’t like the look of Solarhart….but they’re all over Europe. 

Dan



On Apr 10, 2016, at 9:02 PM, Nick Pyner <npyner at ihug.com.au> wrote:

> 
> 
> On 11/04/2016 9:33 AM, Sacie Lambertson wrote:
>> 
>> A PV set-up that produces sufficient hot water you don't have to purchase the gas/electricity to heat water?
>> 
> 
>  I submit that has to be the way to go these days, and solar thermal is just passé, which I understand is reflected in Solarhart's share index.. The bigger the PV array you have, the cheaper it gets, and you can use electricity for all sorts of things, HWS included, while solar thermal just produces hot water and nothing else.  Further, once the solar thermal has done its job, it is simply taking up roof space that could be more gainfully employed producing electricity.  Now I don't know if you are in a position to benefit from any feed-in tariff for surplus electricity, but I bet you don't have any feed in tariff for hot water, and I also bet you won't be charging a battery with it either.
> 
> With PV, you can use a standard electric storage heater and plumbing, the heater doesn't know or care where the power comes from, and any wiring changes should be minimal.  Paying a plumber to go on a roof was never that good an idea and,  if you have electric storage HWS already, it would surely be madness now.  Another advantage of electric storage is that it can probably be painlessly replaced by a heat pump unit, which can significantly reduce the PV demand.  
> 
> There's some food for thought for you
> 
> Nick Pyner
> 
> Dee Why Beach   NSW
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