Categories

Archives

DIY solar hot water controller


the solar hot water system you can see on this blog has cost approximately £200 all in. In particular the flat plate collector was made out of mostly recycled materials! Here in the UK people regularly pay anywhere in the region of £6000 - £8000 for a system which we regard as inferior. And what's more it has a horrific amout of embodied carbon due to shipping from China. So have a go yourself and we hope this blog will assist you in your system design and construction..
below you'll find the blog area which we're updating constantly with new info regarding the controller...coming soon...a dedicated PCB!!!


display module with 4 button interface...

here’s a shot of the new 2×16 lcd display module.  Tony’s mounted it on a parallax propeller proto board so it’s got the microcontroller on the back…there’s also 4 buttons to have a play with.  now I need to program up some sort of 4 button interface to control setting variables in the code…

still doesn’t [...]

propeller pin assignments table…

here’s a graphic showing how we’re going to allocate the 32 pins on the propeller microcontroller.  using a parallel lcd display is much cheaper than serial but uses up quite a few pins.  if you need more free pins then it’d be worth considering a serial display.

parallax serial terminal…a star!!!

readings coming back from the pst.

first readings fed back…

here’s the old laptop kindly donated by swoz.  it’s showing the readings from the analogue to digital ‘lash up’ …to be honest they were’nt all that credible and whilst the syetem functioned fine it was clear that digital to digital was the way to go…

same system showing the sensor wires coming in…

‘lash up’ in place and controlling the system…

here’s a pic of the analogue to digital controller in place controlling the solar flat plate hot water system.  it worked pretty well but we kind of knew that it wasn’t going to ‘cut the mustard’ and would eventually be replaced…

the analogue ‘lash up’…

here’s the first attempt…it’s not pretty but it sort of did the job that was required of it (thanks to tony)…there’s an analogue sensor (can’t remember which one) and an ADC and that feeds into the parallax propeller chip which decides whether to turn on the wilo pump or not using delta T.

controller...

and so to the controller…here’s the parallax propeller microcontroller demo board with an ADC chip (analog to digital converter) in test mode on the breadboard.  To start with the controller needed an ADC as we used analog temperature sensors but we switched to digita sensors  as they don’t need extra components and are more or [...]

pump and filling the system..

once the panel was finished it was mounted on the roof and plumbed in…the picture is of the pump that was choses.  wilo gold standard central heating pump that operates at 18watts on the most economical setting.  system was filled with water and a pressure of 1 bar acheived by simply running a hosepipe up [...]

…and out came hot…very hot…water!!! :-)

eureka!  it worked a dream…in the photo you can see the outpipe.  must have taken the photo before testing and then got so carried away with the results that I forgot to take a shot of the steaming hot water that resulted…

testing for leakage…and hot water

it was a hot day so I hooked up a cold water hosepipe…

after a hard day's work...

harry bathing in reflected glory…

assembled panel…

glass top

harry (dad) holding glass scrounged from a local glaziers who were happy to help. it was originally a £200 sealed unit that I got for £20 because it’s seal had failed.  was destined for the skip.   because the panel only needs single glazing I’ve only used £10 worth so far so if there’s a [...]

putting the collector together…

here’s the collector and frame just before being assembled…the frame is made out of a ply board with a timber surround and a kingspan sheet for insulation…

Propeller port assignments

approved Propeller controller PCB port assignment table

paint it black…

after cleaning off all the flux everything copper was given a coating of matte black stove paint.  it’s rated to 650 deg C so should hold up all right…

the flat plate collector…

here’s an image of the collector all soldered up…took about a kilo of solder to get a good contact between the collector plate and the copper pipes…

here goes…

the first posting on the blog!

what’s needed is to trace back a number of steps and show how we’ve got to where we are now…we’ll do that with lots of photos and documents to show the history of the system.  any questions please put a comment on the relevant posting and we’ll get back to [...]