So there I was pondering whether to fit a Willis Solasyphon ( at £305.00 + Vat) or an additional 250 litre solar hot cylinder ( at £400.00 + Vat) in the roofspace.
And commented to Senior Managment that I would probably go with the evacuated tube system.
Denise, being an Astro Physist, immediately commented that the panels should track the Sun, and indeed be ground mounted for optimium orientation. Though the amount of plumbing would surely render this impractical
Is there any such a system, for roof mounting, with a two panel set up and modern microelectronics surely this should be reliable and affordable?
jat
M

Hi,

The Willis works just fine I have one on test for a while now, paid for so no loyalty or obligation to Willis.

250 litres in the roofspace = around 275 Kg so you may need to increase support under the proposed cylinder.

The only tracking system I have seen was on a solar PV system, looked more trouble than it would be worth for a domestic thermal system, actually the owner was questioning his own decision as the increased gain was very small which he discovered while waiting for a replacement motor.

Thanks guys,
Specifically Tychware, I had not "figgered" on the diffusion due to cloud
Second Peter, no worries I would be mounting above a stud wall (or corner of walls ) below,
hell, I could even mount it directly above a dense masonary 150mm wall ( I think?)
and Miked, yes I found a neat sketch demonstrating how evac tubes effectively track the sun, neat,
and erm the missis somewhat exasperatedly said "obviousley it would be cheaper, and simpler and more straightforward " to mount a % more tubes rather than piss around with a tracking system
doh, bloody physists and their Spockian logic
I am now attempting to resolve the pros and cons of the two different set ups, I actually have room in the hot press to set another solar hot cylinder beside my existing one, plumbed in parrellel?, ie domestic hot water "teeded" in at the top and cold feed/ thermo syphonic recirculating "teeded" in at the bottom.
ie copying the Willis Solasyphon plumbing system/diagram
My "ponder" there is in the winter when the main cylinder is heated by the boiler, I am heating twice as much water, and i do not want to piss around with thermostats , motorised valves etc between the cylinders, but then in the winter we need space heating so this heat is not "lost".
i am crap at making decisions
thanks again guys
cheers
Marcus

Posted By: orangemannotOr does a PV installation with surplus electric first dumped into immersion heater(s) make more sense?

This, in general. I believe the consensus is that PV is cheaper, but with the caveat that you need a larger area of PV panels to match water-heating panels. So if you have a very limited space available you may be better off with water-heating panels, otherwise go for PV and a diverter as you said.

I am also toying with the idea of switching to an unvented plumbing system, since our local watermain has now been upgraded, mostly to do away with the cistern in the roofspace, though my existing system is still perfectly functional.

Unvented does away with the cistern and such things as shower pumps. The plumbing needs to be in good condition to cope with the extra pressure and there's more regulation and maintenance for a pressurised cylinder. I'm not sure I would consider changing over unless I had to rip most of the system out for some other reason.

The economics are changing back in favour of ST already, after March 2019 even more so.

Domestic PV is less economic now than investing in community schemes.

Also worth considering is PV with a heat pump depending on other aspects of the building etc.

Evac tubes from Navitron or ecosolar

Go to a boilermaker and get them to make the perfect cylinder that you need.