[grahamread]

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How did you record these values?

They are recorded from 1-wire temperature sensors - I bought just the sensor (relatively cheap) and wired them up myself using a straw and some heat shrink tube to make a temperature probe; and telephone cable for the network. The sensors draw power from the 5v USB line from the computer.

Connects via USB (see above link) to a small cheap second-hand laptop running linux, digitemp and rrd database to record the data over 24 hrs.

The graphs I posted were from the windows os version of digitemp. Unfortunately my cheap second hand laptop gave up the fight after 3 years in the warm airing cupboard! I've switched to a small cheap eeepc running a version of ubuntu (linux), using linux version of digitemp. Graphs aren't quite as nice, but do the job (see below).

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quite chuffed that I have been able to make something myself

Absolutely. I cheated and bought the EV tubes - although I did install it all myself and kept cost down by plumbing straight into an existing HW cylinder (i.e. no pressure stuff often required for closed loop systems).

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It's really sad I know, but on the 2 days in the last week when it has been sunny I have been keeping an eye on the tank

In that case, judging by threads on other forums, there's quite alot of 'sad' people around the country doing the same! - that or watching their solar PV inverter

Can't beat a bath or shower in hot water that's been entirely heated by the sun!

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This post has been edited by grahamread: 10 March 2012 - 00:30

[grahamread]

Chris Lloyd, on 25 March 2012 - 21:11, said:

Well, my now 2 homemade panels got all 140 litres in my cylinder up from 16 degrees to 31 degrees yesterday. A very respectable 2,6 Kw/h of heat energy.

And it's only the end of March.

Good stuff. The recent weather has been really good for HW and PV production!

[Christopher]

Well, in the warmest day of the year so far my 2 homemade panels heated my entire hot water cylinder to 56 degrees C. 52 yesterday. Used a lot of the water last night for a bath. Base of tank started at 24 C this morning, with a head of 37 degrees. So to heat the whole lot up again to 56 degrees - quite impressive from around 1.75m2 of solar collector ( 1 radiator and 1 flat panel collector).

Back in May when we had a few nice days the water got up to 51 degrees.

Just goes to show how a bit of DIY can work wonders

[Flatlander]

Christopher, on 24 July 2012 - 22:34, said:

Well, in the warmest day of the year so far my 2 homemade panels heated my entire hot water cylinder to 56 degrees C. 52 yesterday. Used a lot of the water last night for a bath. Base of tank started at 24 C this morning, with a head of 37 degrees. So to heat the whole lot up again to 56 degrees - quite impressive from around 1.75m2 of solar collector ( 1 radiator and 1 flat panel collector).

Back in May when we had a few nice days the water got up to 51 degrees.

Just goes to show how a bit of DIY can work wonders

Good stuff. Much better use of the sun than photovoltaics!

Did you just use a radiator painted black or something more sophisticated? I assume you use a secondary circuit with a heat exchanger and a small pump?

Been thinking of dabbling myself...

Ah - I see you posted before as someone else . Sounds like a good setup.

This post has been edited by Tim Prosser: 24 July 2012 - 23:09

[Christopher]

Yes, same old Chris.

My first collector was made of a sheet of metal with 25 metres of 10mm copper pipe braced to it and painted black, enclosed in an insulate box with glass cover. When we had our heating replaced I asked for a cylinder with a second coil. The collector is connected via this with a 38W pump and a solar controller (works great - cost only 50 quid and has frost protect on it).

The first collector measures approx 0.75m2 and last year on the best of days heated the whole tank up to around 38/39 degrees.

Earlier this year I stripped back a radiator, painted it with high temp black paint again and enclosed it in a similar box. This is linked in series to the other box. The other box has the PT sensor so water circulates through this one without choice when the other flat plate collector demands it. I now have around 1.5 /1.6m2 of heated area. The 2 boxes sit on a flat bedroom roof - we have a dorma style house.

A shame that summer wasn't a bit better. You really realise what it does when you place your hands on the circulation pipe at the end of the day and it is too hot to touch. Collector was still at 62 degrees at 6-30 last night. I find being flat it seems to work better because it gets sun throughout the whole day from around 9am until 6pm atm. The flat roof is only around 6 ft from the apex of the roof. In fact the only shadow we briefly get is from the chimney onto the panel. I can see why evac tubes are angled- they need that proper heat at the hottest part of the day. My system (the water) only gets up to around 65 degrees so I believe it requires a more prolonged heat exchange.

[Peter H]

Tim Prosser, on 24 July 2012 - 23:07, said:

Good stuff. Much better use of the sun than photovoltaics!

Did you just use a radiator painted black or something more sophisticated? I assume you use a secondary circuit with a heat exchanger and a small pump?

Been thinking of dabbling myself...

Ah - I see you posted before as someone else . Sounds like a good setup.

We've got solar PV, I have to say I'm (while initially sceptical) pretty impressed that they're producing very much in line with the predicted figures we were given. I don't see much to doubt their projected lifetime output will be right. I can't understand the opposition to them - here in the SW especially it seems to me they add another ingredient to a sensibly diverse energy generation system.

Solar thermal. We're thinking of this but, aiui, the installation costs are very high - esp if you have a gas boiler and no hot water tank. However, I can do plumbing and maybe some kind of diy kit might be a way forward...

Oh, and I was at one of those places with such diy setups the other day. It was one of the most recent cloudy days but the hot water was indeed to hot to touch.

This post has been edited by Peter H: 25 July 2012 - 08:34

[Christopher]

Peter H, on 25 July 2012 - 08:33, said:

Oh, and I was at one of those places with such diy setups the other day.

One of 'those' places LOL? You make it sound illegal.



200 pounds or thereabouts for my system and it has probably paid for itself already.

[grahamread]

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Solar thermal. We're thinking of this but, aiui, the installation costs are very high

..or go for a hybrid approach. Buy an EV panel (or two), but plumb it all in yourself.
Last few days our system has got the HW *very* hot. It automatically dumps HW water if it reaches 85C ( ). Bit wasteful, but prevents boiling; and it only happens a few times a year on days with continuous sunshine and low household HW consumption.

PV producing over 20KwH a day; makes a nice change from last few week's dull weather.

This post has been edited by grahamread: 26 July 2012 - 10:15

[ldavidcooke]

Hey Graham,

Did you say you had hybrids...? Almost impossible to find here.

Been looking to EverBright on ebay for the panels (roughly 1£/watt). In order to go hybrid, would have to remove the Silicone encapsulate, smear on some lithium grease, apply a thin paper barrier and then either a thin aluminum or copper plate then either silver solder aluminum or copper tubing to the plate and reseal with silicone.

Doing this for what would be (12) 1m X 2m panels (est. at 300£ ea) and then paying another 300£/panel for installation is a bit much. By the time we fork over another 600£ for the water heater..., well 12000£ for 2.5kw/hr and free hot water is a bit... taxing..., even with 30-50% Gov. tax credits, which dwindled out 2yr ago...

(Still not sure how you guys do it, were still writing down the losses to savings and homes from the bubble bursts here...)