Doing the Math on Solar Water Heaters

[Forrest]

Re: Doing the Math on Solar Water Heaters

C1ue,

I gave the Co-op a call, and am waiting for them to get back to me...being a very small little business (maybe 10 workers, including the line men), it may take a little time for them to get me the information, but I told them why I wanted it, and I hope they will get back to me with what you need.

And the General Manager called me back...a really nice guy. I told him a bit about your attempts to get info from the big companies, and he was glad to give a kinder response, although they really are just his best estimate as the Co-op buys everything in bundle, and seeks to run the place at only a very slight profit.

We have about 4400 households currently pulling power, althought there are about 600 more households hooked up to the Co-op.

However, these households are spread out over an area of approximately 360 square miles, with a lot of hidden valleys, nooks and crannies to build a house in and have almost no one know where you are.


The Co-op pays about:

$0.07 KWH bundled;

plus $0.01 for transmission,

plus $0.02 for distribution.

He couldn't be much more specific as the KWH are purchased as a bundle and some costs are just part of the bundle.

I sure hope this helps you C1ue.

[c1ue]

Re: Doing the Math on Solar Water Heaters

would seem that Li type would be the way to go - have some hitech.mil grade flashlites with Li batts that claim a 'min of 10yrs' storage life - they still working with batts from 2004(? mightve been 07, so not sure of that)

The thing to beware of with all of the newer battery types is that they don't stand up well over time, as well as being thoroughly expensive.

One benefit lead acid batteries have is that they can be reconditioned. Not something for the faint of heart, but if you're really concerned about the end of the world...

$0.07 KWH bundled;

plus $0.01 for transmission,

plus $0.02 for distribution.

He couldn't be much more specific as the KWH are purchased as a bundle and some costs are just part of the bundle.

I sure hope this helps you C1ue.

Thank you for the info.

Your co-op's numbers are comparable with what I see with FERC reports for the large utilities; this highlights the transmission/distribution payment problem.

[lektrode]

Re: Doing the Math on Solar Water Heaters

I'll be happy to ask questions...I have three different contractors coming out, one Thursday, one Friday, and one on Monday. Just give me a list of questions I can print out.

By the way, how much voltage can I store for about $3000.00 - $5000.00?

not sure i have any questions, other than what are(type) the batts that you mentioned to raja?

but in my example above, using AGM type - 16kwh @ 12vdc = 5or6 x 8D size @ 600ea (or so appx 'wholesale') = 3grand

these are 255 AmpHour rated (so 255 x 12v = 3060watts or 3kwh per 8D) - but when one is running on batteries, the only number that makes sense to use is amps x hours of draw time = amphours - as using 'watts' is too confusing for anything other than panel output ratings - or/and unless when one is measuring things in KWH's - but when you are draining your batts, the ONLY thing that matters is HOW MANY AMPS are ya pullin and how many hours will you be pullin on em for... why i also recommend having an amphour meter - simple device, counts the amps flowing in/out of the batts or net result to the batts of draw vs charge = takes all the guess work out of where yer at, capacity-wise (like, have the batts refilled by sundown? and how much did we use last night?, vs whats the wx going to be like today? and will we need to run gen to refill?, or can wait til sun does it and NOT pull the batts down more than 25-30% or so, with 50% being absolute max draw - unless you like replacing them often ;)

and IMHO - if one is going to be strictly off-grid, i'd rec using a 12v battery system (and PVpanel config), as then one can use commonly available boat items for lights, pumps, refrig etc - and altho 'commonly' available doesnt necessarily mean 'cheap' -
since how do you spell 'expensive' (in the boaters world) ?

M A R I N E
;)
but... 12vdc stuff is still easier to get/cheaper than 24 or other voltage stuff

and if one is depending on batteries/PV, as i said above - its better to have as much of your demand directly on the batteries vs thru an inverter - that way you can shutdown the inverter when you dont need 120vac - and typically can save enough amphours to run a refrig (on DC), again, typically the largest single draw - its also handy to have most of yer critical stuff running on DC, for if/when the inverter craps out... that and if yer genset craps out, you could always run a wire out to yer truck/car/tractor and use its alternator to charge, if nec

i say all this as a boat guy, but i'm pretty sure the land types will tell you different - but let me tell ya...
my airline pilot clients tend to appreciate my POV, since just like when one is at 38,000feet and something goes haywire, ya cant just pull over and look under the hood - and when one is 1500mi out in the middle of nowhere on the high seas
and you lose your electrical system?

yer dead.

why i say keeping as much load on DC as possible makes quite a bit of sen$e, if bullet-proof reliability is a concern

[charliebrown]

Re: Doing the Math on Solar Water Heaters

I don't think it is really inefficient. Each kilowatt-hr that goes in comes out as heat. It does not just disappear. However ...

Last January I used 180 therms of gas. at 40 cents per therm. Looking up the conversion I see there are 30 Kwh of energy in a Therm of gas. Therefore I would use 5400 KWH of electricity. With my little 1 kw windmill operating at 500 w, half the time, I would only be generating 6KWH per day. Which is only about 3% of my heating needs.

Another way to look at it my windmill generates 180 KHW of electricity a month worth about 15$ worth of electricity.
Or another way, 180KHW of electricity is 6 therms of gas which it 2.40 cents.

[Forrest]

Re: Doing the Math on Solar Water Heaters

Lekrode said, "not sure i have any questions, other than what are(type) the batts that you mentioned to raja?

That battery that they have now with a 25 year warranty is a gel type marine battery...very high dollar! But this is why I am getting a total of 6 designs...there are a lot of ways to manage what I need to begin with. and buying the most expensive batteries is not really my thing, particularly when the contractor suggesting them was asking me to wait a few years to get any batteries. But I need the back up..while I process Veggies to juice, then dry it and store it, I can't have my Refrigerators & freezers going out for 3 days to a week, which happens when we get very high winds, plus I need the continual access to water from my well.


but in my example above, using AGM type - 16kwh @ 12vdc = 5or6 x 8D size @ 600ea (or so appx 'wholesale') = 3grand

these are 255 AmpHour rated (so 255 x 12v = 3060watts or 3kwh per 8D) - but when one is running on batteries, the only number that makes sense to use is amps x hours of draw time = amphours - as using 'watts' is too confusing for anything other than panel output ratings - or/and unless when one is measuring things in KWH's - but when you are draining your batts, the ONLY thing that matters is HOW MANY AMPS are ya pullin and how many hours will you be pullin on em for... why i also recommend having an amphour meter - simple device, counts the amps flowing in/out of the batts or net result to the batts of draw vs charge = takes all the guess work out of where yer at, capacity-wise (like, have the batts refilled by sundown? and how much did we use last night?, vs whats the wx going to be like today? and will we need to run gen to refill?, or can wait til sun does it and NOT pull the batts down more than 25-30% or so, with 50% being absolute max draw - unless you like replacing them often ;)

Nope...don't like replacing things, but doing my installation in bits and pieces doesn't make things easy. I just have to make sure that everything I get can be added onto! Fortunately, I am in open sun in Southern California High Desert Mountains, with 5 acres around...and we get very few days without lots of sun.

Great idea for the amphour meter. This is the kind of information I am trying to learn, and winging it will be somewhat necessary since I can't install enough solar now, and will need to wait until the lawsuit against the estate is over to build on a new kitchen, workroom and solar drying room, then add on more and more solar until I get it balanced out.


and IMHO - if one is going to be strictly off-grid, i'd rec using a 12v battery system (and PVpanel config), as then one can use commonly available boat items for lights, pumps, refrig etc - and altho 'commonly' available doesnt necessarily mean 'cheap' -
since how do you spell 'expensive' (in the boaters world) ?

M A R I N E
;)
but... 12vdc stuff is still easier to get/cheaper than 24 or other voltage stuff

and if one is depending on batteries/PV, as i said above - its better to have as much of your demand directly on the batteries vs thru an inverter - that way you can shutdown the inverter when you dont need 120vac - and typically can save enough amphours to run a refrig (on DC), again, typically the largest single draw - its also handy to have most of yer critical stuff running on DC, for if/when the inverter craps out... that and if yer genset craps out, you could always run a wire out to yer truck/car/tractor and use its alternator to charge, if nec

i say all this as a boat guy, but i'm pretty sure the land types will tell you different - but let me tell ya...
my airline pilot clients tend to appreciate my POV, since just like when one is at 38,000feet and something goes haywire, ya cant just pull over and look under the hood - and when one is 1500mi out in the middle of nowhere on the high seas
and you lose your electrical system?

yer dead.

why i say keeping as much load on DC as possible makes quite a bit of sen$e, if bullet-proof reliability is a concern

It is, and I thank you for you advice. And those batteries sound useful for the interim until I have the whole system on new Zinc Air batteries, once they start making them!

[Forrest]

Re: Doing the Math on Solar Water Heaters

I don't think it is really inefficient. Each kilowatt-hr that goes in comes out as heat. It does not just disappear. However ...

Last January I used 180 therms of gas. at 40 cents per therm. Looking up the conversion I see there are 30 Kwh of energy in a Therm of gas. Therefore I would use 5400 KWH of electricity. With my little 1 kw windmill operating at 500 w, half the time, I would only be generating 6KWH per day. Which is only about 3% of my heating needs.

Another way to look at it my windmill generates 180 KHW of electricity a month worth about 15$ worth of electricity.
Or another way, 180KHW of electricity is 6 therms of gas which it 2.40 cents.

Ouch! How do you figure the therms for gallons of propane? I thought of getting a small windmill, until my source for the funds got complicated by the lawsuit, and then I wondered about the noise, and my neighbors complaining about the 30' installation messing up their view.

I want to dump a lot of my propane for spot heating with electricity, and a good old fashioned Ben Franklin Stove...I know the people at a custom wood mill about 1/2 a mile from me, and can get hardwood for next to nothing as they don't have time to chip it or compost all of it...they just like to give it to their neighbors if you'll pay for the cost of moving the stuff on one of their big tractors.

[c1ue]

Re: Doing the Math on Solar Water Heaters

I don't think it is really inefficient. Each kilowatt-hr that goes in comes out as heat. It does not just disappear. However ...

That's not true. Every kwh that goes into an electric heater doesn't come out again - or at least cannot be used again - but this doesn't mean it is all converted to heat.

The numbers are typically fairly high though - in the 95%+ range.

However, the efficiency I referred to wasn't for this. Using electricity to pump heat - as in refrigeration - is 50% more efficient than trying to convert the electricity directly to heat. This is the efficiency difference I refer to.

Last January I used 180 therms of gas. at 40 cents per therm. Looking up the conversion I see there are 30 Kwh of energy in a Therm of gas. Therefore I would use 5400 KWH of electricity. With my little 1 kw windmill operating at 500 w, half the time, I would only be generating 6KWH per day. Which is only about 3% of my heating needs.

Excellent illustration of the difference between cost and heating capability.

[shiny!]

Re: Doing the Math on Solar Water Heaters

Ouch! How do you figure the therms for gallons of propane? I thought of getting a small windmill, until my source for the funds got complicated by the lawsuit, and then I wondered about the noise, and my neighbors complaining about the 30' installation messing up their view.

I want to dump a lot of my propane for spot heating with electricity, and a good old fashioned Ben Franklin Stove...I know the people at a custom wood mill about 1/2 a mile from me, and can get hardwood for next to nothing as they don't have time to chip it or compost all of it...they just like to give it to their neighbors if you'll pay for the cost of moving the stuff on one of their big tractors.

Clarian makes little plug-in wind generators and solar panels. I dunno how cost effective they are for what they can produce, but they're cute:

Clarian SmartBox Wind Turbine

Clarian SmartBox Plug-in Solar

[charliebrown]

Re: Doing the Math on Solar Water Heaters

hmmm curious, where does the < 5% of energy go if it does not come out as heat? It is somehow reflected back into the source? Lost as radio noise or something? I do see that they are rated from 95 - 100% afue. Does that take into account a blower fan?

[c1ue]

Re: Doing the Math on Solar Water Heaters

hmmm curious, where does the < 5% of energy go if it does not come out as heat? It is somehow reflected back into the source? Lost as radio noise or something? I do see that they are rated from 95 - 100% afue. Does that take into account a blower fan?

Primarily leakage into ground.