Has anyone got solar water heater? + some electric bill stuf

[jtbo]

Just little question in a title.

I'm building batch heater (maybe correct term?) for summer use, heat insulation to barrel outside + old house heating radiator painted black and put into insulated box, maybe I get some water heated that way for bathing and dish washing, that will be seen. I try to make it so that I would not need a pump, but if I need a pump then I will be lost, I have some very low power solar cells, like 1-3w, but I doubt those will run any pump.

My powercompany fails constantly to deliver power in one piece they cut it to multiple pieces and it does irritate me when I'm cooking and power goes out, so I decided to give them small signal and try to minimize my power usage during summer.

I also try to build wind generator, but that might be still quite difficult to use, here is no wind, year's average is below 4m/s also at ground level there is only one direction where I can get wind from and it is quite impossible to get that fan up high, it would require ton of permits and paperwork etc.

Anyway I know what kind of windmill I will build, making generator is bit gray area still even I have read how to find out how many coils etc, but still, also some minor details of construction are something I need to think about. I would love to go maglev bearing route, but I have never heard or seen anyone do vertical axel bearing with such, so I doubt that it is possible, I could make guide with conventional bearing and I would think that adding magnets around axle housing and to axle it should in theory leviate at middle of axle housing, it would only need guides, at least horizontal axle levitates that way, so why not vertical?
Still I have not seen it done, which puzzles me a bit and it might be that I go to traditional bearings instead, which would be again boring and with these low winds less effective.

[Speedy88]

Heh, eco houses are fun. Is there a water source near you? Water harnesses loads of power. Also, how much rain do you get per year? If you could channel all the rain from your roof to one pipe you could engineer a small battery charging generator. If it rains all the time there, that's a lot of energy

[Chris_C]

Me and a friend keep looking into similar, but in a rented house it's not really an option. Another mate has solar water panels on his roof, they are epically efficient and thermosiphon so don't need a pump. Certainly far better than anything photovoltaic is yet.

There has been a fairlyish recent breakthrough of solar cell efficiency at my uni, found a new way of making silicon near matt black so that you don't get the reflections of a current panel (for all light you reflect doesn't count towards that you can convert) It'll be on the new Richard Hammond program on Discovery soon.

Something I really really want to try is a solar power low delta T stirling engine connected to a high efficiency alternator/dynamo. Efficiency from a few beermat calculations should be around that of a current solar panel yet as it's a delta T rather than photon powered device it'd work in reverse if the ground became colder than the air temperature

What are you going to use to store all the power? With your house location I'd be really tempted to make an uphill reservoir and pump water up to the top during the day, then release it via a water wheel generator when power is required, would make an awesome garden feature too

[jtbo]

There are lot of problems in this area to get lot of use from this stuff.

Some averages to shed light to problems:
Wind level from 50m above ground is under 4m/s year's average. Highest winds are under 10m/s, good thing is most winds are from west, as I have narrow gap to west where from wind comes quite well into yard.

Sunshine, long time average for full year is 1611 hours of sunshine, in this graph choose line Jyväskylä each column is month starting from January and last bold column is total in a year, values are solar radiation in MegaJoules per square meter:

Problem with sun is also that it is almost 270 degrees during summer months that sun runs around the sky, but can't get more than 140 degrees around south to use, actually it is more towards east and not very much to west from south that I have good sector, from 3pm at summer it starts to be impossible to harvest, even 8pm still would be possible to get power from.
During summer time 717 is long time average amount of sunshine hours and because of complicated nature of water heating systems during freezing perioid I will limit usage to summer time.

Rain then, worse stats from that, but we get around 230mm rain in whole summer, that is long time average, but problem is that because of tall mountains of Norway and sea between Sweden and Finland we get quite odd weathers, rain is between 50mm and 425mm in a summer, there is no way of telling how much it will rain next summer, it is El Nina summer, which should mean lower rain than El Nino summer, according to stats (we do get cold during El Nino years, but not always, I told you, weird weathers).
Last year there were not too massive rains, lot of thunderstorms sure, but it was bright blue sky after quick storm, I doubt that we would get much of rain that could be used for energy generation purposes. I do have rather long roof in one section, but it is not continuous, so I doubt how such would work in these conditions. If I would have small river or something like that, then naturally I would build up some generator to water as water power is lot better than solar or wind, it is rather easy to predict and quite strong too.

I'm not too eco minded, even my water usage is less than half from average finn and my electric usage is ridiculously small for person living in private house, but as I always say, there is no need to buy zillion eco thingy, just using common sense would do much better

I use 4 liters of hot water as an average per day, usually if some eco minded persons comes to discuss about my V8 gaz guzzler, discussion will end up short when I ask how much they use hot water or how much they produce waste to to garbage can, where I can make out with only one small shopping bag in whole month and that is maximum, it is just different way of thinking I believe.

So I try to minimize my water heating needs, that is a priority as water heater makes half from my power bill, cooking related activity makes pretty much 3/4 from that half that was left, uhm, I'm not good with fractions So during summer I can cook some amount outside, if I can make dishing water with sun and bathing water too, then my power bill would be very tiny, if I get windpower, then I could perhaps charge laptop with that. Buying as little electricity as possible.

Solar heater is very efficient, however it would require selective glass to make it really really good, I don't know how hot I can get it, but if anyone has touched matt black metal during hot sunny day, that gives perhaps some idea? One friend has those vacuum solar collectors, he already gets all hot water that he can use from those and it is around 0C outside!

To get some serious power, I would imagine that parabolic mirrors and Freshnel(spelling?) lens stuff would be neat, you can make metal red hot with those things just

I must say that I was shocked how shitty that stuff is that is sold today to get 'green' power, those wind generators would not even start in here, if does, then all generated juice would be used in controllers, solar panels are 10-9€/square meter and they would need tracking, to get some power out from those I would need a field of them connected to giant battery, each time when I did the math I had to do it again, it felt that I was mistaken, but no, power that would be possible to get out after all losses is very minimal in these conditions that I have, when putting five figures onto table, then there would be capacity, but the cost would still be far greater than bought electricity. That is why I choose to do my own systems from stuff I already have and some would be minimal investments, that way everything I do is a win, even if I would not get lot of power out from these, at least I don't loose much of anything, also it is quite satisfactory if one can do something that gives free hot water or free electricity

Chris, I'm looking forward of that new cell technology, it should boost sales and make prices go down eventually, current technology is indeed rather weak, so only pioneers will get those PV panels at the moment, pretty much same for windturbines too, but there are better solutions than what is available at PV market, also wind turbine is not impossible to make yourself, try to make PV cell

For that solar water heater insulation is very important, we have very cold nights during summer, specially at early summer, also every degree of temp above air temp causes loss of energy, so with good insulation there will be less loss and system will produce warmer water, it can even boil, I have heard, but if I use some 200 litre plastic barrel (i have metal barrels but those are bit oily or rusty), it should store good amount of heat and maybe not boil so easily. One hose connects to up, other connects to down and those connects to house heating radiator which heats water, it should circulate by itself if I manage to do it right, top of radiator to bottom of barrel and so on I guess ? Also I guess that barrel should be above radiator, so it does need bit of thinking too. then need to think about hoses and maybe pipes, pipe would be better if water is going to be really really hot, also bit easier to insulate, but hose is easier to connect, however that is not too great of problem really.

To get some idea of location, south is right from yellow building, I think that photo was taken somewhere between 4-5pm, not quite sure, sun is quite close to west.


edit: Piccie rather big, mod resize seem not to operate, or takes long, click url:
http://jtbo.pp.fi/images/house/house.jpg
To get most of sun stored to barrel, whole system would need some wheels so I could cart it around the yard chasing the sun
If I would install full year system, then I could put stuff on roof, storage section's sun get's lot of sun during day.

[sven360]

Lampoassa are your friend.

Ground heat source would give more consistent results I would think.

[jtbo]

That would come with ridiculous price, easily 20K in this area, amount of time to get investment to pay itself back would be something longer than anyone can wait.My power bill is under 400 in a year, ground heating uses electricity too, also when you calculate interest for loans, note that it would require installing complete new heating system inside the house etc, it would be very questionable if investment will ever pay itself back. Same with solar and wind power if one buys them from shop. I consume too little, those things work only in huge complexes when power usage is lot larger.

Comparing that to under 50 euros investment which pays itself back in one or two summer's, I really don't see any point.

[sven360]

I personally think your pv solar plan will not work with 50euro investment.

I hope I'm wrong and look forward to your results.

Over here to get any decent water heating you need a good site for maximum output and some monster pv units.
Cost for the units would be in excess of£2k before fitting.

[jtbo]

Ah, but I'm not doing it via PV route, PV panels have theoretical power conversion rate of 15% from what comes in - all the losses top of that, however even a simple self made solar collector should get over 20% from radiation to water tank very easily, as good commercial ones can get 70-50% from sun's radiation harvested. Friend did calculate his system with based on 2 square meter per person and he gets already all hot water from sun and last night it was still -15C
Well, that is fancy vacuum tube and coolant mix circulating etc, but anyway, compared to PV panels these directly water heating devices are much much better.

I was only thinking of using existing pv panels to priovide electricity to pump if needed, however I think that I go to pumpless route.

Key to good working system would be insulation, pipes, storage and even collector must be made so that heat can't escape, but it still have to enter, so I need some kind of door to my collector.

There are stories by people who have made those things, haven't read much of those, but will do as better to learn from other's mistakes than make your own, even there will be _lot_ of mistakes in my build no matter how hard I try not to make them, somehow they always jump in from behind the corner...
http://www.builditsolar.com/Projects/Wa ... .htm#Batch

BTW, it is pretty darn hard for me to read all those sites that have information about things as all they seem to care is eco enviroment bla bla, trying to pick what is realistic and really important between lines is sometimes challenging as quite many place is just lobbying eco greeny things without much of common sense, like for example wind turbines and PV panels, sure PV panels great in Arizona and Wind turbines great in open sea, but when things come to level of realism we can see that for example wind turbine, average amount of which best possible turbine would harvest here would be around 4 watts per square meter, however it could be that weeks damn thing would be not spinning, pretty much same goes for PV panels and solar collectors too, if you don't live on coast that is a desert, then nothing will work as those greenie sites promise. So have to read, then have to translate, then have to try to figure out true nature of things when green coating is removed and finally can get to somewhere, that somewhat irritates me, why they will not write stuff as it is in engineer point of view, that would make sense? Sorry for rant, again

[jtbo]

I got some heat, painted radiator black and put it against sunny wall to let paint dry, quickly it was +33C inside and that is with moderate freezing cold wind, next to sunny wall of house I did measure +5C outside temp, ton of snow everywhere. I would imagine it working somewhat ok when put into insulated box.

[pyro]

I try to make it so that I would not need a pump, but if I need a pump then I will be lost,

thermal siphon -



its entirely possible,
we've got a log burner in our house. gas bills are non existant, as it heats the whole house, and the plan is to connect a back boiler to it over summer to heat the water over winter and summer.

Ben

[jtbo]

This first summer I will not have even to worry about tap connections and stuff like that as adding and extracting water would be done manually, opening lid of barrel and so on, but hunger grows bigger and probably in no time I will be adding heat transfer unit to preheat water to my electric water heater

I wondering here how much heat standard garden hose would take, I would need only short pieces of that to connect copper pipes to radiator, but I wonder if it starts to melt in sun when put into closed heater box, maybe better to use automotive rubber hose?

Here is formula to find out how much energy is needed to heat up water:
Water in kg x 4.18kJ (constant for water don't know what word it was in english) x C degrees how much you need to increase temperature

So for example if I have 150 litres of water that is +15C and I would like it to get +40C that is 25C rise in temperature, it goes like this
150 x 4.18 x 25 = 15675kJ of energy is needed.

Here sun heats 214Mj for each square meter at this moment, 1 Mj is 1000kJ so I have 214 000 kJ for one square meter available, that is 7133kJ for each day as an average, that means that I will need at least 2.2 square meters if my solar harvesting is 100%, but as it is not we can easily double this estimate and add bit of extra, so we round number to 5 square meters, that is how much I would need of solar collector area to heat up 150 litres of water in one day at this time of year. Still that would require me to turn solar collectors facing to sun a whole day, so there is lot of things that one need to think about, that is 44% efficiency, I don't know how possible it would be, maybe not quite so.

2 months from now and sun heats whopping 552Mj for each square meter, more than double what it does now, so I can heat same amount of water easily with 2.5 square meters of collector surface area. So far I do have only one square meter of radiator surface, but I do have 2nd one somewhere, just need to find it, then I should find 3rd one somewhere (naturally free as two I already have did not cost even a penny to me).

I'm not too good with math, but I guess it would be possible to work out formula that calculates how much thing heats water from surface area of collector and total solar radiation to square meter. Also I have no idea how this would work with imperial units, I did however manage to make some calculations with Gnumetric spreadsheet which did give me some square meter estimates, 3 square meters would be something that might work, 4 square meters would not harm.
Problem is that one can make too powerful system, then water easily boils and that is huge mess which should be avoided.

[jtbo]

First half of single radiator box is ready, weather just got cloudy so I could not test how it will affect the performance and should some tweaking to be done. Now I need to make upper section that holds glass and lid, then it need some insulation and after that it should be ready to use. Of course still need to make box where reservoir will reside.

[sven360]

The fundemental flaw with solar power with regards to heating water is when you want a cool shower you have a lot of hot water.
But when you need a red hot bath you have lukewarm water.

[jtbo]

The fundemental flaw with solar power with regards to heating water is when you want a cool shower you have a lot of hot water.
But when you need a red hot bath you have lukewarm water.

That is where reservoir capacity and insulation comes into play.