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#366984 - 28/06/2016 18:53 Re: Electrical Usage Strategy [Re: Phoenix42]
K447
old hand

Registered: 29/05/2002
Posts: 798
Loc: near Toronto, Ontario, Canada
Originally Posted By: Phoenix42
Originally Posted By: DWallach
What I like about these numbers is that you're now incentivized to store your electricity rather than feeding it back


How feasible would it to set up, your presumable hot water heater, to only run when there is an excess of solar energy, rather then all the time? Although this could leave you with cold water in the morning, maybe just restrict the lower element, so the upper can still heat a smaller amount of water.

In other word, without resorting to batteries and other means of storing energy, is there a way we can automatically consume the excess PV energy when it is available, rather then sell it to the grid at a low price, only to buy it back later for double.

I have my own selfish reasons for asking, there is a housing development going in the next town over, that we may buy into in two years time. The houses are HERS 55 rated (24" stud spacing, 6" insulation + R12 sheathing, triple glazing, etc), all electric, and PV ready. I expect at some point, that National Grid will push a similar plan to yours, so I'm curious what options exist to balance things short of battery, or a Tesla.
You can assemble more than one electric water heater into a storage group, or even better, heat the water with a rooftop solar water heating system. Store up the excess hot water in several tanks.

Keep going with that thinking and you end up with waster circulation heating of the building plus plenty of hot water for other uses.

Storing electricity looks to be on the cusp of becoming economical. Choose a house layout and wiring that can accommodate future battery wall packs (or whatever) and install them when the pricing matches your criteria.

Long term I think the grid will become the backup and the local electricity storage will become the primary.

What does PV ready mean in this case? Just some wiring, or a roof design with maximal southern slope exposure and structural mount points for the solar array frames?


Edited by K447 (28/06/2016 18:55)

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#366986 - 28/06/2016 19:43 Re: Electrical Usage Strategy [Re: K447]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5546
Loc: Ajijic, Mexico
Originally Posted By: K447
or even better, heat the water with a rooftop solar water heating system.
Like this. It provides water hot enough that I have to be careful, and in sufficient quantity to serve two apartments.

Interestingly, even on a hot day when many things are uncomfortable to touch, those glass tubes transfer heat so effectively that they feel cold.

tanstaafl.



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P1110131-W1024.jpg


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#366990 - 28/06/2016 21:34 Re: Electrical Usage Strategy [Re: tanstaafl.]
K447
old hand

Registered: 29/05/2002
Posts: 798
Loc: near Toronto, Ontario, Canada
Originally Posted By: tanstaafl.
Originally Posted By: K447
or even better, heat the water with a rooftop solar water heating system.
Like this. It provides water hot enough that I have to be careful, and in sufficient quantity to serve two apartments.

Interestingly, even on a hot day when many things are uncomfortable to touch, those glass tubes transfer heat so effectively that they feel cold.

tanstaafl.

Precisely like that.

Those vacuum insulated tubes can provide hot water even in cold Canadian climate and on moderately overcast days.

If there was a cost effective way to convert excess thermal hot water into electricity, PV and batteries would not be needed.

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#366991 - 29/06/2016 00:25 Re: Electrical Usage Strategy [Re: tanstaafl.]
JBjorgen
carpal tunnel

Registered: 19/01/2002
Posts: 3584
Loc: Columbus, OH
Originally Posted By: tanstaafl.
My neighbor across the street with a big swimming pool and a casual attitude about leaving lights on runs up bills in excess of two hundred dollars a month, compared to my usual twelve or so dollars.


Yeah, our first house here had a pool and the pump ran 3 hours a day, which coupled with our normal power usage, pushed our bill to $3500 pesos ($195). I'm looking forward to lower bills at our new place although I haven't gotten the bi-monthly bill yet.
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~ John

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#366994 - 29/06/2016 02:33 Re: Electrical Usage Strategy [Re: JBjorgen]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5546
Loc: Ajijic, Mexico
Originally Posted By: JBjorgen
pushed our bill to $3500 pesos ($195).
Is that for one month, or is that the bi-monthly bill? My neighbor was $7,000 pesos plus on a bi-monthly basis.

tanstaafl.
_________________________
"There Ain't No Such Thing As A Free Lunch"

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#366996 - 29/06/2016 03:57 Re: Electrical Usage Strategy [Re: K447]
Phoenix42
veteran

Registered: 21/03/2002
Posts: 1424
Loc: MA but Irish born
Originally Posted By: K447

What does PV ready mean in this case? Just some wiring, or a roof design with maximal southern slope exposure and structural mount points for the solar array frames?


Honestly I didn't ask, it was just the RE agent I was speaking to. But the impression I got was it was just the wiring. Looking at the overall development layout I didn't notice anything special being done for solar alignment.

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#366999 - 29/06/2016 12:16 Re: Electrical Usage Strategy [Re: JBjorgen]
Tim
veteran

Registered: 25/04/2000
Posts: 1525
Loc: Arizona
Originally Posted By: JBjorgen
Yeah, our first house here had a pool and the pump ran 3 hours a day, which coupled with our normal power usage, pushed our bill to $3500 pesos ($195). I'm looking forward to lower bills at our new place although I haven't gotten the bi-monthly bill yet.

How effective was the pump only running 3 hours a day? When I had my pool resurfaced a few years ago, they recommended an hour for every 10 degrees of water temperature.

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#367001 - 29/06/2016 18:36 Re: Electrical Usage Strategy [Re: Phoenix42]
DWallach
carpal tunnel

Registered: 30/04/2000
Posts: 3810
Originally Posted By: Phoenix42
Originally Posted By: DWallach
What I like about these numbers is that you're now incentivized to store your electricity rather than feeding it back


How feasible would it to set up, your presumable hot water heater, to only run when there is an excess of solar energy, rather then all the time? Although this could leave you with cold water in the morning, maybe just restrict the lower element, so the upper can still heat a smaller amount of water.

In other word, without resorting to batteries and other means of storing energy, is there a way we can automatically consume the excess PV energy when it is available, rather then sell it to the grid at a low price, only to buy it back later for double.


We've got two 50-gallon natural gas water heaters (piped in series with one another -- which my plumber says is something they'd never do any more). In the summer, they account for the bulk of our gas bill, which will hover around $25/month. I'm looking to replace them with a new high-tech hybrid tank or a tankless, either of which would be radically more efficient. So storing excess electricity in hot water isn't particularly attractive.

What is attractive is over-air-conditioning the house. While the usual environmentally friendly thing to do is to run the AC less during the day when you're not home, then have it come up to speed when you're on your way home, I could instead keep the house cool all day, perhaps even cooler than I want it when I'm home, consuming a big chunk of my excess solar production. This is better for the house, in some regards (cooler air = drier air => less mildew/mold), but would put more wear on the AC compressor/motor.

If I were super high tech, I'd bury a cold water tank in the backyard and I'd store chilled water, for the AC to use whenever I needed it. Chilled water distribution is commonly used in commercial system, where they might chill water all night, when power is cheaper, and then use it all day. If I were building a house from scratch, I'd look into this. Needless to say, it doesn't appear to be an easy retrofit.

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#367004 - 29/06/2016 19:27 Re: Electrical Usage Strategy [Re: tanstaafl.]
JBjorgen
carpal tunnel

Registered: 19/01/2002
Posts: 3584
Loc: Columbus, OH
Originally Posted By: tanstaafl.
Originally Posted By: JBjorgen
pushed our bill to $3500 pesos ($195).
Is that for one month, or is that the bi-monthly bill?


That's for two months, but we were living on the edge of DAC for several months and then in December with all the Christmas lights and tree, etc.. we went over and wow! the bill more than doubled for just a few more kwh than before.

Originally Posted By: Tim
How effective was the pump only running 3 hours a day? When I had my pool resurfaced a few years ago, they recommended an hour for every 10 degrees of water temperature.


I know next to nothing about maintaining pools, but it seemed to work great. We only had trouble twice in the year when the chemical balance got off a bit and it got a bit green until the pool guy came and fixed the chemical balance.
_________________________
~ John

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#367016 - 29/06/2016 22:44 Re: Electrical Usage Strategy [Re: JBjorgen]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5546
Loc: Ajijic, Mexico
Originally Posted By: JBjorgen
That's for two months, but we were living on the edge of DAC for several months and then in December with all the Christmas lights and tree, etc.. we went over and wow! the bill more than doubled for just a few more kwh than before.
For the majority of people on this bbs (at a guess, I'd say all but the two of us!) there is no understanding of what DAC really means.

It doesn't mean that for that one month with the Christmas tree lights you paid a penalty. It means that for however long it takes, every subsequent bill will be at the DAC rate until the total usage over the 11 previous months plus the current month adds up to less than 3,000 KWh. This is made even more complicated by the bi-monthly billing, so that even if your total annual usage at the end of December totaled 3001 KWh, you couldn't get out of DAC until the end of February.

tanstaafl.
_________________________
"There Ain't No Such Thing As A Free Lunch"

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