navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Solar Tea / Coffee  (Read 10858 times)
Ivan
Guest
« on: March 21, 2008, 11:16:28 PM »

Anyone started making Solar-powered tea in Navitron tubes yet? We've certainly had enough sunshine on some days recently.
Logged
Ivan
Guest
« Reply #1 on: April 03, 2008, 07:48:59 PM »

Come on! You could have saved yourself a kWh or two today by drinking only solar-kettle boiled tea/coffee
Logged
rob26440
Hero Member
*****
Offline Offline

Posts: 515


Clear off birds!


« Reply #2 on: April 03, 2008, 08:56:52 PM »

Not in Berkshire you couldn't!  Barely saw the sun at all today - just a glimpse after 6pm when it was disappearing.  Anyway, why would I want to stand on a step ladder to drink coffee out of a 6ft tube?
Logged

S/E England. 30x58mm tubes, S/W facing 40deg pitched roof, 216L primary and 184L secondary cylinders, TDC3 with home-made, separate controller to switch between cylinders, 15mm tubing with min 25mm insulation.
rob26440
Hero Member
*****
Offline Offline

Posts: 515


Clear off birds!


« Reply #3 on: April 03, 2008, 09:00:11 PM »

...Also, the dear lady baulks at climbing on the roof to bring the tube down.
Logged

S/E England. 30x58mm tubes, S/W facing 40deg pitched roof, 216L primary and 184L secondary cylinders, TDC3 with home-made, separate controller to switch between cylinders, 15mm tubing with min 25mm insulation.
guydewdney
Hero Member
*****
Offline Offline

Posts: 4320



« Reply #4 on: April 03, 2008, 10:48:35 PM »

my panel hit 93 degrees today - kettle arrives tomorrow... tea a bit later...
Logged

Pic of wheel on day 1
7.2kW Waterwheel and 9.8kW PV
guydewdney
Hero Member
*****
Offline Offline

Posts: 4320



« Reply #5 on: April 15, 2008, 08:20:52 AM »

aparantly not Sad


tip - dont leave tube in sun before adding water:_



* waterwheel 055.jpg (108.84 KB, 640x480 - viewed 1133 times.)
Logged

Pic of wheel on day 1
7.2kW Waterwheel and 9.8kW PV
Flamethrower_
Hero Member
*****
Offline Offline

Posts: 745



« Reply #6 on: April 15, 2008, 09:00:18 AM »

Guy,
 
Thats thermal shock for you  ! (cold water -> hot glass ) oops!

Same effect as people have done defrosting car windscreens (hot water -> cold glass) b*gger it! wackoold

Rob
Logged
Ivan
Guest
« Reply #7 on: April 15, 2008, 06:41:50 PM »

Oops. Yes, the tube will be rather hot if empty and exposed to the sun. I've managed it -by very very slowly tipping the water in, which gives great puffs of steam, but I wouldn't recommend it - I've not broken one yet, like this, but I do have an unusually large number of spares  Grin
Logged
guydewdney
Hero Member
*****
Offline Offline

Posts: 4320



« Reply #8 on: April 15, 2008, 07:44:45 PM »

yeah - the guy who poured it in is a bit heavy handed...  Roll Eyes
Logged

Pic of wheel on day 1
7.2kW Waterwheel and 9.8kW PV
rob26440
Hero Member
*****
Offline Offline

Posts: 515


Clear off birds!


« Reply #9 on: April 16, 2008, 08:48:28 AM »

Guy,

I was going to say: "No use crying over spilt milk".  But you didn't get that far.  whistlie

Rob.
Logged

S/E England. 30x58mm tubes, S/W facing 40deg pitched roof, 216L primary and 184L secondary cylinders, TDC3 with home-made, separate controller to switch between cylinders, 15mm tubing with min 25mm insulation.
wookey
Hero Member
*****
Offline Offline

Posts: 3220


WWW
« Reply #10 on: July 01, 2008, 06:55:57 PM »

I've just started this - all solar tea/coffee today.

One bit of advice though - don't leave tube out overnight for morning start as first mug has boiled beetle in it. (Devils coachhorse - nice and big!). I put a rubber top-cap on, but maybe the bottomcap type would be better as it's beetle-proof, but once it's nice and boiling that may be less than ideal as no vent.

Also I'm going to end up with a lot of calcium deposits on the inside of my tube if I carry on with this. That could be cleaned off with vinegar/other acid but I worry slightly about the coating. How immune is it to random acids?
Logged

Wookey
Ivan
Guest
« Reply #11 on: July 02, 2008, 02:26:11 AM »

Nice idea about using the spare bottom rubber cap - I hadn't thought of that one. I use a cork with a small hole for thermometer.

You do get a little bit of calcium inside (I suppose it depends on amount of water you put through it and local hardness) - it's never been a problem for me, and I use it quite a bit. You can clean the tube with a bottle brush attached to a dowel with masking tape - it's very effective. I've cooked soup in tubes, and forgotten to put the empty tube out of the sun, so soup residue burns onto inner glass surface of empty tube. I was surprised how easy it was to clean - a few rinses when cold, then filled the tube with water, and left in sun - boiling water soon stripped off any remaining residue - I didn't even need to use the bottle brush!

Don't worry about the selective coating - it's on the vacuum side of the glass, so won't be affected by anything in the tube. Each tube of boiling water you use saves you 0.15kWh of energy (if you are using gas, you'll save at least double that, due to gas stove inefficiency - discussed recently on another thread). Last summer I was managing three cycles per tube per day on a good day. If I got up earlier, I expect it would be possible to manage 4.
Logged
wookey
Hero Member
*****
Offline Offline

Posts: 3220


WWW
« Reply #12 on: July 02, 2008, 10:53:25 PM »

Ah, OK, good to know I'm not going to damage the coating - it's suprisingly hard to tell which surface it's on from just looking. So yes that makes hard-water deposits pretty harmless too.

Even if you buy an extra tube for the purpose it'll pay for itself in about 350 sunny days at 4 cups/day. Probably a couple of years in practice. I reckon a balcony-sized tube would be rather more practical in pouring-convenience terms.
Logged

Wookey
Ivan
Guest
« Reply #13 on: July 03, 2008, 12:38:34 AM »

Navitron have balcony-sized tubes too - 58mm diameter, 750mm length. Haven't used one personally, though.

For me, today was heavily overcast virtually all day, and several heavy showers as well. I filled a tube last night, so it was out from dawn onwards, although it would be in the shade until about 11am (assuming there had been some sunshine to cast shadows!). At teatime, we poured it into a pan to cook pasta. It was at 72C - demonstrating that even on a poor day at this time of year, it can be useful for something. Wouldn't be enough for a good cup of tea, but probably ok for coffee.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!