Choice of intelligent switches ?

hp4020 wrote: »

Choice of Immersion Switches

Tempted to go for the Intelligent Solar Immersion Heater Switch – Mark II @ £233 delivered for self install.



but noticed the Immersun, twice the price.

http://www.immersun.co.uk/

I have already changed immersion to a 1kw element, so think ISIHS Mark II is the one I will go for.

http://solarimmersionheaterswitch.co.uk/shop/solar-pv-immersion-heater-switch/intelligent-solar-immersion-heater-switch-mark-ii/?gclid=CMvZtdS-kLICFcfKtAodCGkAgg

Thoughts ??

Is this the same one on eBay for £199 + £4.99 del?
Looks good, but how long is the payback time?

I'm sticking with ESE's idea until next year.
Cost less than £25.00 if you put it together yourself.
No mains tie-ins(1kw immersion is ideal)
Not expecting to gain as much in the winter months compared to summer.
Used virtually no gas(hot water) since I fitted it.
Will update when I get my next bill.
Many new products should be available and prices will fall.

grahamc2003 wrote: »

But seriously, I'm surprised on an environmental board, no one has commented on the anti-environmental effect of converting high grade daytime energy (electricity) into low grade heat (hot water) when there are much more efficient means of creating the low grade heat (gas). Environmentally of course, surplus solar generation (that is, by definition, expensive daytime electricity) should be exported so others can use it as a high grade energy source, and save it's generation from a power station.

Actually it's come up many times over the last few months, on various threads.

Tricky to do this from memory but I'd guess the first mention was probably about 3 or 4 months back, and I believe a discussion between Roger and James (or maybe Celerity), so long ago, hard to remember.

Mart.

Our Immersun is getting installed today. Likewise I'll be posting updates as to how it goes.

Martyn1981 wrote: »

Hiya Hobbo, can I ask a genuine question, and I promise I'm not stirring nor criticising. Is that £120 valuing the leccy at zero?

If you were on an export meter, how would the numbers work out at 3.2p or 4.5p? Anything that helps make PV more financially rewarding, will of course improve it's viability (to those who can fit such systems) and therefore help to speed up it's roll out and the leccy and gas/oil savings that it brings.

So I'd be very interested in your thoughts, just so I can squirrel a few more numbers away for consideration.

Thanks again.

Mart.

Hi Mart,

I suspect Hobbo is guestimating the savings based on Electricity 'cost' of zero. Due to deemed export the actual amount of electricity export is irrelevant unless you either have an export meter (very uncommon for domestic installs) or have a Smart Meter which can record export (I doubt these actually exist yet other than in prototype form). Therefore for now at least it is a safe assumption to assume that the 'cost' of the electricity is indeed zero.

Our Immersun installation is done but hit a snag in that the immersion element is a dead duck, so needs replacing (along with the faff of draining the tank). As that'll need a plumber we'll probably get the tempering valve fitted at the same time to mix down the hot water to a safe temperature as it leaves the tank.

Unless Hobbo's gas is very expensive (ours is 3.7p/kWh inc VAT), his gas boiler very inefficient or he has a very large array I doubt he'd achieve savings of £120/year. Using our gas price and assuming the immersion is no more efficient than the boiler (for simplicity of calculation) he would have to dump around 3240kWh of spare electricity into his hot water tank, or just under 9kWh/day. Our 3.7kWh system has averaged 9.5kWh/day of generation over the past ~10months, so we couldn't have exported 9kWh/day unless we were only using 0.5kWh.