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Forum Index : Solar : Heating With PV Panels
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Murphy's friend Guru  Joined: 04/10/2019 Location: AustraliaPosts: 648 |
I'm doing exactly that Davo, after you came up with the idea of using that heat source. I looked at Bunnings for materials, the corflute sheet was way too flimsy, no way to get it even from the shelf to the cashier without crumpling it. For a similar price I got a 1800 x 900 x 3mm sheet of MDF which suits my 175W panel and I can use the offcuts glued on the back to reinforce the inlet and outlet holes. I have some of that blue sarking left over which will get stuck to the inside of the MDF backing, silver side facing the solar panel back. Of course MDF is not weather proof at all so it will get painted all over, a great project to use up that half tin of leftover paint  . |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
Last quote 12 months ago was approx $130 for a sheet of 1.5mm, size is 2440 x 1220mm, trade. PSP Go to a sign writer and get some corflute, it comes is various thickness's, it isnt structural, you have to place it into your box, require 20mm timber spacer around the inside edges with a cross brace and staple using stainless stables, then seal with a bead of silicon; last sheet of 6mm cost me $20. Mike |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Sarking! That's what I was trying to think of today! But I didn't see that either. Their insulation seemed pretty limited to that earth wool batt stuff. There was a lot of things they were out of stock quite clearly. I'm not sure how thin it comes, but I have read that Chipboard is far more water resistant than MDF, although it's not great either. If you have plenty of paint on the MDF particularly the edges, should be fine. other possibility for a backing would be that Blueboard. That's waterproof and comes pretty thin and is also stiff enough in solar panel sort of size. Cut that out, layer of sarking spray glued on, attach with some Tek screws, done. Was thinking to make a double panel arrangement, easiest thing might be to secure the panels together once the backing is put on with solar rail and clamps. That way the ducting between the panels could be done in PVC and fitted up permanently. Also need to make some legs to hold the things up and preferably oversize to give the things some stability in the wind... although could still peg them down. The prevailing wind will be side on but it does some weird things here at times and could come from any and every direction within 10 Min. I'd like to put the electrical power to use as there seems to be worth while heating power to be utilised there was well. For my application, I might think about heating a drum of water placed in the corner of the en suite to give some lasting warmth after the sun has gone. Might be the best way to go. 1 Kw of panels should give about 3Kwh a day average in winter which would give about a 26O temp rise on a 100L of water. If I am getting 3 Kwh of electrical energy, if I get twice the heat from that panel surface area, ( playing devils advocate) that should be 9kwh effectively all up. Sounds too good to be true but again can't see where I am going wrong. I'm basing the electrical energy off calculators I have found to be surprisingly accurate and everyone says the thermal energy should be 3 times the electrical so... That's what it works out at conservatively. 1 kw of panels into 9kwh of total energy? Wow but really? I get very suspect when things seem too worthwhile. Then again, if I got 6kwh total, still seems a winner. That is going to make it possible to warm the ensuite, the dressing room and the Bedroom! If not heat, it will certainly keep the chill off! How good would it be to walk into a warm bathroom for a change! Worth every bit of effort. Got another hair brained Idea I might try tomorrow as well. |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1022 |
Not sure where I should put this? I warmed the place up a bit today, probably over done, The fan sucking heat in from the roof cavity was turned on at about 10:00am, any time before then its still cool air, also there is no solar panels on the roof so that might make a difference for some. After that I took out the little window mounted (1500w cooling capacity) aircon and put the bugger in the other way round, Turned it on and screwed the thermostat all the way down, and yes it was still too cold outside for the unit to work, The portable unit could be turned down a lot further and had no problems, not cold enough to bother it yet. By about 11:30am the little window unit aircon fired up, took some time for it to pump out some worm air (out the back of it) but ended up pumping out a temp of 35c, the same as ceiling exhaust fan was doing, the outside of the aircon built up a lot of ice, but after some time that also disappeared. Finished up with 25c by 3:30pm inside the house after starting at 17c can't complain at the moment, some aircons will do better than others and a reverse cycle aircon will obviously do better in colder areas. Cheers Aaron Off The Grid |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
That's pretty good from the roof. From memory mine when I tested it was no where near that. Looks like I'll have to get up there again tomorrow and take some more readings. Haven't get many ( relatively panels on the the roof atm so that may make a difference especially as half the north side is uncovered. Maybe the sarking will be working against me at this time? No, that's pretty good! I made offers on a Lot of portable units. They seem the same as panels. Everyone thinks they are worth a fortune despite the fact there are 50 of them for sale in half as many Km from me. When I offer something for sale and have had no offers in a month or 3, I tend to reconsider my asking price and take what I can get... not that I have ever had anything for sale for 3 Months which in the words of the Aussie Legend, " There dreamin!" Seems many just make up a price in their head and anything lower is just someone trying to rip them off. Ah well. They will still have them no doubt when summer comes despite the ones with the hypocritical " Need it gone" comments which always accompany something which is grossly over priced! |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Finally a complete and creditable test today. Got out and with much anguish and removal of fast depleting follicles and a growing solar panel on top of my head, managed to secure the ducting to the blower, which then fell out and had to be secured in the back of the panel. Same temps as normal, 13 in both rooms. Interesting seeing last night did get down to 3 but I did notice the west wall seemed a couple of degrees cooler than the south wall which I found curious in the ensuite but everything else I measured was well within half of a degree. Had it running by 10:30 still half shaded and was pleased with the 190 air. ambient was about 15 at that stage. By Mid day I was getting 25 which somehow went up after a realignment to the sun of 28 at 2 Pm. temps measured were around 20 in the ensuite and about 16 in the dressing room. Mrs did leave the door between slightly ajar so maybe there was some creepage of warm air in there . Not a problem. Show was over at 4 Pm and everything in the ensuite was sitting at 21. Dressing room was leaning toward 17 but most checks were still showing 16. Maybe tomorrow I'll leave the between door open and see how that goes. Top ambient I saw was 19 which agreed with weather report. It still feels really cosy in there and the warmth is noticeable as soon as you enter. Going to make for a nice comfortable shower tonight. See what Mrs thinks. She was a bit dismissive of the idea this morning and said what's the point, we are barely in here. Different to what I though she was thinking. I said yes but when I am in here with my butt exposed I want it to keep warm and I don't want the Crown Jewels Icing up and enough shrinkage going on I have to look twice to find things. I also pointed out the bedroom was a bit fresh at night which she has commented on ( why doesn't the heater warm up here? Ummm, because it's 20 M away?) and the final setup should make them all quite cosy long as the sun is out. So I'm pretty happy with an 8o rise. Yes, the area is tiny, about 4m x3 ( bigger than our last bathroom at 2x3 though!) But this was from one single panel with a bit of cardboard on the back ( that the tape is letting go of anyway) in a less than ideal location. Ramp it up to 2 or 4 panels ( which I can then Grid tie or use for heat) and the setup will provide significant and VERY useful heating. Probably push through the Ensuite, dressing room, bedroom and into the hallway and take care of that end of the house. Or do I just buy another diesel and be done with it?? :0) Tomorrow is forecast to be promising ( probably come down cats and dogs) so if it is similar, will be interesting to see if there is any warming or heat soak effect. The hours of no heating grossly outweigh the hours ( and temp difference of when there is) so my hopes are not high but many things with this have already surprised me. Multiply the output x4 and things may change. I can now see the benefit of these things done properly. If the panel as Mike says is loosing 40% of the heat it gathers, then a well made setup would be impressive! I did find a channel on YT about heating Roger and Mike are probably familiar with but I hadn't seen before and found very interesting. Solar test setups Guy has done a LOT of different ideas and measured and reported on them Very well. I not a lot are done in summer for water heating. Results are inspirational But for me, have so much solar electricity to burn in summer just no need but his work is very good just the same and would be useful for those whom don't have a PV overload in summer and still a deficit in winter.... :0( And being the genius I am, I finally worked out why they use drink cans for these solar air heaters... because they are even cheaper than I am and don't want to buy any pipe for the job.... and I thought I was a tight arse! Geez! I was thinking of this too. Just putting lengths of 10mm Pipe up on the roof and Pulling air though that. Yes, I realise uncovered would be less efficient but the stuff is like $16 for a 6M length. Some T pieces and maybe 90s to turn down for the ends to stop sucking things in ( and some flyscreen) and you could get a lot of meters coverage for very little work and cost. On the roof would probably help a lot with heat gathering as well without anything else helping. I reckon 4 6m lengths of 100mm PVC spaced half a Pipe length apart would give some decent output on any sunny day. Secure it with a bit of that metal strapping into the roof screws and done. I will be interested to have a look tomorrow if worth while at the roof space temps again. Massive collector area but unfortunately has a membrane specifically designed to to keep that heat out. Wonder what the ideal setup would be? No sarking but double the batt insulation on the ceiling to keep the heat out in summer with whirly bird vents so summer that could be closed off for winter? I have seen people put car radiators in the ceiling with fans for transferring the heat to water which they can then circulate in the house which is an interesting idea. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
it comes is various thickness's, it isnt structural, you have to place it into your box, require 20mm timber spacer around the inside edges with a cross brace and staple using stainless stables, then seal with a bead of silicon; last sheet of 6mm cost me $20. The solar panel frame will be my box, I think I'll go with them as less than ideal as they may be. Heat will be a bonus and I could rack and use 8 panels in a run if I want. I'll do a ground mount and see how it goes. I Might tek screw the corflute on with some washers at first and then if all is good silicone would be an easy and effective way to attach it. A brace isn't a bad idea, I might use some wire to stop it sagging too much in the middle if it does. I have also seen somewhere these little plastic standoffs. The ones I have in mind were white, about the size of 2 Bob and had 3 or 4 legs like a table. I thought gluing a few of them on the back of the panel may be good to make sure there is clearance as well but I can't think what these Might be for or where I have seen them? Might have even been for cakes or something. Looking at the guy aboves channel, Might be practical to have an edge on the top of the panels and just wrap some clear plastic over the top to help reduce heat loss? Thanks for your input and help Mike, Very much appreciated. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
Some encouraging results Dave, well done. I know winter's supposed to be cold and gloomy, but I am surprised how many good days we do get. Cold maybe, but still a reasonable amount of light. The dark days are almost enough to put you off ... but the good days keep you going. They're not the little spacers they use in pizza boxes to keep the lid from sagging onto your pepperoni and cheese?  Aaron, since you mentioned the air temp in your roof cavity being worth harvesting, I put a datalogger in my ceiling about 30cm under the peak to see what ours was like. We have black tiles, so would have thought it would be reasonably high. After 6 days I took it out and downloaded the results. Definitely a dead loss for our house. Temps were very poor.  Cheers, Roger |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Genius! That's what they are! Found them on fleabay.... in bulk lots. Now, who do I know that works in a Pizza Shop? And you have black Tiles? Sarking under them I presume? Can't get near my roof in summer, Mt recollection of winter temps up there were not promising as well. I'll check again but given your results tie in with what I remember.... Like Inverters. Get hot enough to fry eggs on if uncooled but it winter with very similar power running through them they are barely warm. The temp difference is in no way Linear to the ambient difference that's for sure! I thought about putting a couple of them in the laundry which is right behind them last year but when I looked at the temps they were running at, no heat to be had.... when you want it of course! I expect the en suite will be cold as ice tomorrow morning. Zero here atm and I can feel the place cooling despite having the diesel heater going.... which I just kicked up a notch. Edited 2021-06-07 02:32 by Davo99 |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I just found a sheet of that cool room insulation. Its made by a company called foamular-metric. https://www.architectureanddesign.com.au/suppliers/austech-external-building-products/foamular-metric-brand-extruded-polystyrene-xps-1# Its some special kind of extruded polystyrene foam. It has a very fine grain structure and is waterproof. It has the visual appearance of MDF, but is vastly lighter in weight. I used it when I was experimenting with casting aluminium parts. Because of the very fine grain structure and its mechanical rigidity, it cuts and machines very well and can be sandpapered into smooth shapes. That can then be buried in casting sand. When you pour in molten aluminium it instantly disappears down to nothing, and is displaced by the aluminium producing a very nice aluminium casting. Its an ideal method if you only want to cast one simple part. This is not my invention, to the home metal casting mob, this is a very old and well established proven method. It would also work very well with a CNC router if you wanted to cast several identical parts. Small simple sections can be glued together for making up more complex shapes. Anyhow I digress. This stuff is fairly rigid, you could build a solar collector box out of it, not just use it as an internal lining. Its all so long ago, I cannot now remember where I bought it. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
That looks ( from the crappy Pic) very similar to other products I have seen. Bunnings has something which sounds Similar in small sheets which is Green. I think it's also something I have found they are using as insulation for exterior walls. Because of it's board similar rigidity but easy to cut, they are using it to insulate houses, existing houses by just sticking it on the outside walls. It can then be covered as with weatherboards or Blue board or even bagged and rendered Direct. Pretty sure I have seen it or something similar being put on the walls of new homes being built round here. Maybe I should go for a drive round some of the new local future slums they just keep throwing up unabated round here and see if I can pick up any off cuts or damaged sections. From memory what I saw said it came 100MM thick and had a very high R value. got to admit, got me thinking about this place or at least doing a couple of walls. Funny you mention Casting ally and Lost foam. I made some cast ally sculptures some years back pouring ally over those water expanding gell balls. Mrs loved them and for the last month has been on my back to make a load more to sell online and maybe at local markets. I recently saw where people were doing them with chunk ice as well. That would probably give a different look and pattern to the gel balls and wouldn't have the thing going everywhere and have to wash and dry them out of the casting. Plus they stink to hell when the ally hits them. We were in a cheap shop the other week and I spotted styrofoam balls and said to the Mrs how daughter had been talking about some of her friends still interested in the polished aluminium balls craze. They make them out of tin foil and must hammer it or compact it some way and get it to a polish-able surface. Daughter said she was laughing at the work they were going to. Laughed and said my Dad could probably turn out 10 of those things a day. She told them he used to melt aluminium all the time, He'd just pour the aluminium into something to make the ball then just polish it on the grinder. Kids were apparently fascinated and a bit disbelieving I could melt ally so she showed them some of my YT vids. I said did you tell them I can melt copper and iron as well? Mrs wants me to do these balls to offer for sale as well. Had the idea of doing a load of them about 20MM for table decorations. I said have you any idea how much work that would be manually casting them by the hundred? Might have to get her brother to machine me a 2 part 20 spot mold or better still, I'll build a shot tower in the back yard. Bet that will calm her enthusiasm somewhat. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
The stuff I have here came in strips 600mm wide and 50mm thick in various fairly long lengths, although as I remember its available in a range of thicknesses. Its perfect for any "on the roof" out in the rain structural type applications. Still have a small furnace here for melting aluminium, runs off natural gas or propane. Metal casting was a lot of fun and pretty interesting, but my interests changed, and I moved onto other challenges..... Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Rooms started off at 12 Today. I opened them both up but shut off the bedroom. Sun is moving off the panel and the day has been pretty hazy, not cloudy but not full sun either. Output temps were down to a best I saw of 24. Checking the temps, both rooms are now 18 and wont be getting any warmer that's for sure. My prediciton about the room retaining heat was spot on. I went in there after mrs had her shower after I have mine and noted the temps in there were about 23-24. The steam and the hot lamps she likes warmed the room more than the solar did all day. This morning was lower than it has been, despite the higher and later temp of the room. Given it was officially zero and always colder here than where the temps are taken, no surprise. The whole house felt on the cool side this morning even out the back where the heater runs so It was definitely a cooler one. Going in there now to take the temps, both rooms are very constant and the same, even in the corners which surprised me some. One interesting accident was the carboard strip I have been sealing the window with I open to stick the Duct in had fallen out. I then noticed that the fan seemed to be running quite fast. I put the cardboard back in and noticed the fan speed dropped. I wondered what I bumped and then though surely not!. Carefully removed the cardboard and the fan sped up, replaced it and after a couple of seconds, slowed again. I'm inside so not shadowing the panel, moving the fan connections or anything else. Must be creating air pressure. I did NOT see that one coming, in fact I was planning on the complete opposite. Like all bathrooms it has an exhaust fan which in this case is ducted outside under the eve rather than into the ceiling cavity. I thought that would be more than enough to let any air pressure, as minimal but apparently not insignificant as I thought it would be at all. this is just a little bilge blower not one of my big jumping castle or dust extractors which really blow a gale. Still disbelieving, I replaced the cardboard again, took note of the air sound, went and cracked the door a good way to stop it closing itself and went back and sure enough, the fan is definitely running faster. I WILL be buggered! I would have thought the crack under the door would be enough of an air leak to prevent that, still cant see how it's not or even why back pressure would have that effect. I would have thought it would have caused the fan to unload and run faster. I think I'll test this again tomorrow. More I think about it the less it makes sense. in any case, if it does work out, I'd have a much larger fan for a multi panel setup so I guess I need to leave the door open all the way to the bedroom as well. I was watching some vids this morning that stressed the importance of High flow, low heat air to maximise efficiency. also made a point about air turbulence and how important that is. Not sure I can do a lot to help that through the panels. Could glue on some foam strips I suppose to make the air move round the panel a bit better. Spose it can't hurt if it don't help. I surmised all the air would eventually find it's way through but maybe the hot pockets that would have to be there are more detrimental than I thought? When I cover the back of the panels I was intending just to leave a gap at the bottom for the air to enter rather than drilling holes that will do the same thing. I might start with 10mm Gap to provide some higher speed air currents which may also be more turbulent and open up from there as I go. Also thought in a multi setup, this should allow some tuning. Pressure drop will be greatest nearest the fan so the gap for the air induction should be the smallest and the gap on the far panel should be the largest. I might need to look at getting a Magnehelic meter so I can balance thing things and get even flow across them all. As I remember they aren't cheap. Wonder if I could do it the same way I used to set up Multiple SU and other carbs on car? Piece of tube up to your ear and listen till the sucking sound is the same across all of them. Only race teams had carb balancing gauges and being race teams, having the carbs balanced on those engines was far less important than on street cars anyway cause they always ran wide open anyhow. I'm going to need a bigger case for all these meters... and loggers I'm getting. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Magnehelics often go pretty cheap on e-bay, it just depends what pressure range you are interested in. A simpler and cheaper way would be a piece of clear plastic tubing bent into a U shape to make a water manometer. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
You insight and brilliance never fades Tony! Had not occurred to me but your mention of it makes it seem obvious. I have 20M of clear hose I use for levelling with landscaping projects. The water in a tube is very sensitive. I'll have a look for a mag meter as it would save mucking round but if I can't find one I can use the water tube. Thanks for yet another clever heads up. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Nothing I could see on e-bay right now raised my enthusiasm. About half of them look stuffed, showing some significant pressure with nothing connected. The ones I have here do change the zero position very slightly, about 1mm or 2mm when the magnehelic is tilted or held horizontal. Some of those were showing a quarter scale. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Motivated by my own rantings, I went down and visited the local stratco about the Verandah across the back of the house Mrs and I have been discussing. I know they are at the high end of the scale but they are good to get design ideas and a base pricing plus their products I do feel are good quality. It's the west wall and so much heat comes in summer making that half of the house that does not have a verandah hot and the Ensuite which is a an ice box in winter, just as uncomfortable though being so damn hot in summer. It's roughly 11 x 2.2m covering I would want. For a basic lean to design attached to the back of the house with roof sheeting would be $5700 delivered, Diy erection. Frame only but with 12 beams ( to attach Panels) instead of the normal 3 was only $3500. The beams are 120 High but 150 is an option as well. These I plan would be the air plenum between the panels and the backing. Looking at my solar supplier current price list, I can buy 500W panels ( anyone know you can now get 670w Panels?? I didn't!) for $195 ea. They are 2.2 x 1.1M so perfect size for the job! That's actually cheaper than the roof sheeting AND... I get a 5 KW solar array and the potential heat capacity which in winter should be another 5.7- 9.6 KWh of heat capacity depending on what the actual losses turn out to be through the panels, ducting etc. Even if it were 3-4 Kw worst case scenario, that seems quite a bonus to me. I also am working on worst case solar radiation so there is likely to be better results beyond the dead of winter when heating would still be required or a nice luxury. I would have to work out how to mount and back the panels/ beams on the other side. The beams are 50MM wide so may be as simple as just stick them down with liquid nails and seal between with same or Silicone. I'm thinking panels on top of the frames and a backing underneath so that acts as the plenum for the heated air and gives a nice appearance. Might be as easy as Gyprock although I would prefer a material that was impervious to leaks. Fibre board may be suitable and cost effective but there may also be some decorator panels that would be suitable and look good. More head scratching and investigation needed. I could probably leave the lower end open for airflow and just work out how to seal the house end and then work out the ducting up into the eave. That's probably going to be the trickiest part but probably a simple solution. I do have a large new AC rated tube fan I picked up a few months ago for a song and that could go up in the ceiling, maybe hung upside down On some rubber mounts for noise suppression and possibly fed into the existing AC duct work with another damper for Isolation in summer. That would take care of the heat distribution nicely and still allow the benefit of directing the warmth to different zones. This seems very practical and doable and very cost effective as well. I imagine in the end it would be slightly more exy than a plain roof pergola however this would have a substantial ROI where a normal setup would have none. I could also use standard size panels, 1700x 1M and an end piece to go to the guttering but I think given the price, the 500W panels would be the go and make things easier and maybe cheaper in the end. If the idea looks viable, might have to buy some of the beam material and do a mock up of the fixings and covering to make sure of it all. At worst, failing all this grandiose planning, My thoughts would be to just get a bunch of 100 or 150MM PVC Drain pipes, paint them black and lay them along that roof. Pipe is cheap as and there is plenty of area to utilise. One benefit of this would be the very easy potential to fill the pipes with water which could make transferring the heat and bringing it into the house much easier and also as we are planning to put a spa under this area, could be used for heating that as well when space heating was not required. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Went out today and Picked up a few bits and Pieces from the factory rubbish piles. one thing I got was a slab of Plywood 1800x 990. Just wide enough to fit behind a panel. I'm out of suitable length screws so back to Bunnys tomorrow to grab some so I can secure the ply to the back of the panel to replace the now buckling and warping Cardboard test Piece. I'll also make up some legs for the panel, Standing the thing against a garden chair with a large pot plant in it so it does not push over is getting a bit old having to move it about. won't be hard to set up the legs so the panel can be moved to say 60, 45 and 30o for a bit of optimisation. I'll also look at incorporating a Thermostat board so the fan only operates when is senses the air in the panel is 20O C or above. The heat will Build in the panel so the thing may Cycle on and off but that's fine. Bursts of warm air are better than nothing and Non inverter AC is all or nothing anyway. I spotted some more Ply on the way home but had a full load so will have a look again tomorrow. If I can get more, I'll start building a multi panel heater. The test setup was working today in the clear warm sun, the first since last weekend I think. Most of the days here have been cold and overcast with a couple not reaching Double Digits. I opened the window this morning, reached out and grabbed the ducting, jammed the window down on it and that was it. Went out for a while and came home and the panel was out of the sun so pushed it out and closed the window. I didn't take any temp readings but the en suite was not at all Icy like it has been this week, ( literally uncomfortably cold to even walk in!) instead was much closer to the temp of the rest of the house which was pleasant and warmer than outside time we got back. I think a panel is useful, certainly would be if one had a panel on a caravan or camper and used the heat as well as the power charging batteries but I think once multiple panels are utilised, the output will become far more worth while exponentially. Somewhat a case of 1+1 equalling 3 as the losses would be far less as a percentage of the heat gained. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
Yes, that seems to work quite well with my arrangement too. I used to think that if the fan wasn't on, that the heat was being wasted ... but it seems to me it is building up a bit like a capacitor charging ... so as long as you run it from time to time to extract the heat that is there ... you get a pretty good result. Certainly much better than pumping in air that ends up very close to room temperature ... feels like it does more cooling than heating. Sounds like we're a bit luckier than you. We had one dud day this week and a couple that had a slow start but came good at least for a while ... but today was an absolute ripper. From 10:15 - 15:45 it stayed above 30 degrees and reached 39.2 at the peak. That's 5 and a half hours with the fan on its highest speed. Got almost uncomfortably warm inside ... but I'll take that. Can't wait to hear your results with the next lot of tests. Good luck. Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Your differential temperature controller should be not too far off. That will automatically cycle, and I expect work extremely well. Cheers, Tony. |
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