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Project Logs / Re: Making the best of Global Warming
« Last post by vtsteam on July 04, 2025, 02:45:31 PM »
Ade I worked for a thin film optical filter firm, and they were getting into solar cell tech at the time. I suggested something similar, except not hot water, a thermoeletric cell integrated under the photosensitive cell with a heatsink on the bottom. The thermoelectric cell works on differential temperature. Efficiency of a thermoelectric cell is lower than a photocell, but it's waste heat anyway,  it adds additional output, and the cooling of the sink helps the photocell's efficiency which drops with increased temp, so the increase could be decent.

Also since there is no water, no freezing problem, and even in winter there is a temperature differential.

No interest.
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Project Logs / Re: Making the best of Global Warming
« Last post by AdeV on July 04, 2025, 02:25:03 PM »
Just looking at Eco Worthy's website again.... Their solar tracker thingybob + 6x 195W panels is coming in at a hair under 72p/watt capacity! That's bonkers! The last (and, indeed, the first...) solar panel I bought was nearly £1 a watt just for the panel alone, without any other gubbins to go with it, although that was a few years ago now. In fact, a single 195w bifacial panel is rather cheaper than the 100W monofacial panel I bought back then. Honestly, it feels like I've blinked, and the bottom's fallen out of the market!

Definitely going to be looking at one (or more, depending on garden size!) of these next year.


 :offtopic:

Speaking of heatwaves.... (we're not having one oop north right now!  :lol:); I believe solar panels lose efficiency when they get hot, which is always a pain as the best sunshine usually comes with a lot of heat too...

So then I got to thinking - which is always dangerous  :zap: - in Ye Olde Days (1970s and earlier) one could have "solar panels" on the roof, but they were thermal panels, not PV. i.e. they warmed your water up... My grandparents had one on their roof for donkeys years... although unfortunately they died & the house was sold long before I got interested in this stuff.

However - I got to wondering: How hard would it be (famous last words!) to create a hybrid PV/hot water panel? i.e. make a normal thermal panel (lots of black-painted copper pipe in a think black box); but instead of putting a glass front on it; put a solar panel on it instead! Now... obviously the panel's going to eat a lot of the potential heat; but since it's going to get hot, wouldn't the thermal panel underneath suck out a lot of that heat? Which could then be used to pre-warm a tank of water - and, given that heating water is one of the most energy intense things we modern people do, wouldn't this save some energy (In summer at least!) by a) using the heat energy, and b) making the panels even more efficient than they already are?

Sadly, winter is going to be its usual problematic self, with bugger all sunshine at low angles & low temperatures limiting any available heat (and one might need to deal with freezing temperatures too)... but I do wonder if, for those hot summer days, it might be an interesting system at least?

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Project Logs / Re: Making the best of Global Warming
« Last post by Joules on July 04, 2025, 02:12:49 PM »
A half circle cam with two microswitches so the controller knows it is East or West facing, then motor till both switches are zero hence level, would be nice.  I'd still be lashing it up in bad weather or leaving it unattended for any length of time,  so really it will do as is.
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Project Logs / Re: Making the best of Global Warming
« Last post by vtsteam on July 04, 2025, 01:52:54 PM »
I like seeing the pictures!

re.wind furling. I was thinking about self steering rigs for ocean going sailboats. In the olde days (like 70's) mechanical self-steering co-pilots used a weathervane to turn the tiller to correct the course. The problem they found was it took a fair degree of deviation from the course to apply enough power to correct the steering. Then someone figured out that instead of a vane with a vertical axis, it was much more effective and powerful to mount the vane with a horizontal axis at the bottom. When the boat turned off course, the whole vane flopped over until it was horizontal, at which point it spilled the wind-- a far greater range of motion than the correction angle of a vertically pivoted fin. These were quicker reacting and stronger as servomechanisms.

I don't know if any of that has application to your wind situation. Maybe a finned switch on a horizontal axis for operating the furling servo. Or a purely mechanical system of furling. it's too bad your present system first tries to limit in the wrong direction, but I'm sure you'll eventually make something to solve it.

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Project Logs / Re: Making the best of Global Warming
« Last post by Joules on July 04, 2025, 09:50:31 AM »
Totally agree on the fun factor.   I just added the final sensor to the tracker, its anemometer.   Pretty useless in these surroundings with buildings and fence.   However it has to be located where footballs have the slimmest  chance of finding it.  The tracker is currently set in storm mode as winds have picked up, so it is lashed.  The anemometer is barely spinning, I do a weather check in a morning before deciding to release the tracker.   It still produces a decent amount of power like this.   I did follow the New Zealand Whispergen for a good number of years, sterling CHP

Power in the UK not quite as bad as your situation, but it certainly could get that way with the state its in.   Electric companies here are worried about the number of people having off grid systems and not paying their extortionate prices for power.  We have plenty of redundancy, the tracker is a gamble to see how it performs over a year or two.   With more space it's a no brainer to go with more panels ground mounted.

We have solid fuel heating here, with Japanese paraffin heaters for colder evenings and days that don't justify the stove which does our hot water and central heating.   No hot water in the summers, been like that for 20yrs+, have a couple of Kelly Kettles we use for washing up.   Washing machine heats its water and we run it off the Bluetti.    Things have come along way since I set up a small panel in a bedroom window many years back before the roof top solar craze to see if it was worth trying.

The workshop solar has been a continuous work in progress, soon to have a major update.
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Project Logs / Re: The Return of No. 83, a Hot Air Engine
« Last post by vtsteam on July 04, 2025, 09:44:07 AM »
Heh, Joules, me, too!  :beer:  I've been talking about building engines since I first built the lathe over a decade ago (supposedly to build engines with). Finally now, I'm starting.

Next step on this one is to go to a Scotch yoke in order to give myself more room for a longer pushrod guide (by eliminating the connecting rod, and reducing side force on the displacer pushrod). I have trouble preventing the displacer from contacting the walls of the displacer cylinder. I think that is reducing power output at times. Hard to tell. Anyway a straighter stroke for the displacer would allow me to add an internal axial regenerator made out of stainless steel foil that I have.

Heh, again, I'm presently caught up in fixing my CNC router to mill out the Scotch yoke itself. So again, briefly caught up in a side project.  :lol:
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Project Logs / Re: Making the best of Global Warming
« Last post by vtsteam on July 04, 2025, 09:17:32 AM »
That's really interesting to me, Joules. In the 90's I lived on a houseboat that I built, and traveled 1700 miles in down the US coast and across Florida. I had a Heart Interface 1200 watt inverter, and unfortunately a small noisy Coleman generator for when the 25 hp outboard motor wasn't running and charging. Three 90 AH deep cycle 12 V batteries. I lived on that boat, off and on, for ten years. It served as a basecamp here on our land while I built our present house 25 years ago.

I would have loved to have had photocells and a more modern storage and inverter system like you have now. I did make a hot water solar collector for showers. I found that 12 V lighting and appliances were useful on the boat back then. The inverter had a charger in it so if I ever did spend the night at a marina, it would transfer switch over automatically and charge the batteries.

Now I do think about alternative power, so it's interesting to see how much more efficient your system is than anything I ever was used to. And how little space your array takes up for that amount of power. We do heat with wood (we live on 67 acres of mostly forested land) and one of my interests in Stirling engines has been with the ultimate aim of making something big that, in the frequent power outages we have could serve for some power. Although for continuous use, photocells make more sense. Both would be ideal. Actually a Stirling would make sense for CHP since we heat with wood.

I'm obviously a long way from producing usable amounts of power via a hot air engine. But I do think it's possible. Well also, I have to admit, building a big Stirling would be fascinating and fun. You have to add in the fun factor in anything, I think.

I still do have the Heart Interface inverter but it stopped working. I think the output power transistor(?s) is the problem but I am not knowledgeable enough about electronics to troubleshoot it. I can solder well enough and once built an LNW-80 computer from scratch - bare boards and ICs etc, but analyzing circuits, nope.
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Project Logs / Re: Quornish
« Last post by Joules on July 04, 2025, 07:09:50 AM »
I came here thinking you had dug a cream mine in Devon Shipto ?

Congratulations on getting way further than I did with my Quorn, though it still has no rust on it.
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Project Logs / Re: The Return of No. 83, a Hot Air Engine
« Last post by Joules on July 04, 2025, 06:34:50 AM »
Wow, very impressive Steve, engine and its back story.   I sometimes wish I could focus long enough to build engines  but something usually comes along and takes my mind off that idea  :palm:
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Project Logs / Re: Making the best of Global Warming
« Last post by Joules on July 04, 2025, 05:17:08 AM »
I was very wary of spending that amount of coin on a Bluetti system  especially considering the YouTube shills promoting it.  I started  by getting an AC180 to run our winter paraffin heater and media PC.  Later got an AC50B and that now runs a Windows laptop and solid state laser cutter, by this point I was pretty impressed.  The AC50B was actually bought to replace an old APC UPS, but found it could do much more.   :lol:  seems I am now a Bluetti shill....   The Bluettis can all be grid charged, or in our case, charged via an inverter from the 12V system we already had.   The big Bluetti can be charged from the tracker and a programmable limited grid supply, so it won't kill our 12v system.  Upto 750W off the tracker and 250W coming from the other system, doesn't take long to fill up, and it does pass through charging so the power coming in can go straight out to other loads.

I have already sold off a couple of generators we used to have, the AC180 replaced a portable Honda I'd kept for 30yrs+   No more storing oil and petrol, especially the bio yuck you get nowadays.
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