Choice of intelligent switches ?

danesol

InVestor wrote: »

Hope you've factored in smart meter rollout from next year.

Smart meters or infact any replacement meter is NOT compulsory - its up to you whether you have a replacement or not

danesol

danesol wrote: »

Well I've purchase the Solar Immersion MKIII switch from solarimmersion.co.uk using the discount code:- dis2204 and we are really impressed and it works really well in conjunction with our SMA based 3KW system :j

Yes, it maynot be as good looking as say the Solic 200 or the Immersun, however we were'nt bothered about what it looks like or the build quality to a certain degree as it has been fitted away from sight in a cupboard - all we were seeking was good functionality at a NO FRILLS price and this is what you get, doing exactly what it was designed to do !!

So if you either heat your hot water via oil, electric or GCH ( condenser ) boiler, you would be foolish not to consider one of these units especially if no-one is at home during the day to use the generated electric which normally would just go to the grid.

Using one of these devices you heat your hot water ( or/and use on another =< 4KW load ) by electric you have already gained revenue on twice;

1. Once via the initial generation - std generation tariff

2. Second via the 50% estimated export tariff

We calculate our return will over 3yrs, replacing £ 80 worth of GAS which would normally be used to heat the hot water cylinder - then pure profit thereafter.

This unit ( mk3 ) has been running now for 3yrs and has served well so far, BUT we think our initial cost saving estimates are well under as this unit within our setting (PV system and actual useage etc) is maximising all excess electric, so we are virtually exporting nothing but been paid for 50% of generation regardless !!

Because of the way the system works, various clamp monitors cant always capture what is been sent to the immersion heater although its own clamp is spot on, however it is very obviously from the panel display, the electric meter been stationary and having the gas boiler completely off with a full cylinder of very hot water each day from ~ April to Oct that it is saving us loads ......

I have been in contact with the company recently to praise them and they tell me that there is a new model with further facilities.

Should you require a Solar Immersion Unit ( mk4 ) now at £199, you can still use the discount code "dis2204" ontop on this !!

I hope to provide some calculations on actual savings at somepoint

hth

zeupater

danesol wrote: »

This unit ( mk3 ) has been running now for 3yrs and has served well so far, BUT we think our initial cost saving estimates are well under as this unit within our setting (PV system and actual useage etc) is maximising all excess electric, so we are virtually exporting nothing but been paid for 50% of generation regardless !!

Because of the way the system works, various clamp monitors cant always capture what is been sent to the immersion heater although its own clamp is spot on, however it is very obviously from the panel display, the electric meter been stationary and having the gas boiler completely off with a full cylinder of very hot water each day from ~ April to Oct that it is saving us loads ......

I have been in contact with the company recently to praise them and they tell me that there is a new model with further facilities.

Should you require a Solar Immersion Unit ( mk4 ) now at £199, you can still use the discount code "dis2204" ontop on this !!

I hope to provide some calculations on actual savings at somepoint

hth

Hi

So you're diverting somewhere around 1000kWh/year to the DHW then ?

Z

orrery

I've got the solarImmersion and I can't get a handle on the savings because things have changed so much since (new boiler, revised C/H system, electric car etc) that I can't make any 1:1 comparison.

I can say that for about 3 months of the year (last year was longer, but this year is proving a bit lacking) we get our daily hot water for free (a bath and a shower plus a bit spare) for free.

However ...
In making all these statements we need to be careful to advise that you do need the right immersion heater - a short 12" top-mounted immersion isn't going to deliver the savings. I've had a 30" fitted, and a bottom mounted immersion would be better.

My best shot is that I now use about 17 cu meters of gas over the 4 best months (I use the gas if the previous day has been shockingly bad, or we have visitors for the weekend) and I used 130 cu meters the year before I had the solarImmersion. So a rough estimate is 100 cu meter = 1100kWh of saving or about £38 per year. Of course, there is contribution in the other months too, but I'm ignoring this as the comparison is with an older less efficient boiler.

So, proper payback would take about 8 years but I'm well happy as I wake up with a free tank of hot water and that is a really great feeling.

danesol

orrery wrote: »

I've got the solarImmersion and I can't get a handle on the savings because things have changed so much since (new boiler, revised C/H system, electric car etc) that I can't make any 1:1 comparison.

I can say that for about 3 months of the year (last year was longer, but this year is proving a bit lacking) we get our daily hot water for free (a bath and a shower plus a bit spare) for free.

However ...
In making all these statements we need to be careful to advise that you do need the right immersion heater - a short 12" top-mounted immersion isn't going to deliver the savings. I've had a 30" fitted, and a bottom mounted immersion would be better.

My best shot is that I now use about 17 cu meters of gas over the 4 best months (I use the gas if the previous day has been shockingly bad, or we have visitors for the weekend) and I used 130 cu meters the year before I had the solarImmersion. So a rough estimate is 100 cu meter = 1100kWh of saving or about £38 per year. Of course, there is contribution in the other months too, but I'm ignoring this as the comparison is with an older less efficient boiler.

So, proper payback would take about 8 years but I'm well happy as I wake up with a free tank of hot water and that is a really great feeling.

I wrote this back in June 2013 on the PVO site which maybe of interest;

"Today, was a bad day for solar generation for us, any power been generated was used internally by the dishwaster etc etc, however some was avail to the solar immersion device, but very little, so my wife had to turn on the Gas Boiler ( 3yr old Valiant Condenser boiler ) at 6pm'sh to ensure she had hot water for her bath, so I found it was time to see just how much it costs to heat semi hot water via the gas boiler - here are my findings, even though the water had been preheated now and then by the immersion device.

Reading after boiler shut off ( Both reading and pic taken after 50mins ) - 2949 [28] 2
Reading before ( picture taken of meter prior to boiler been switched on ) - 2949 [16] 3

Total gas used = 0.12 units
Convert to kwh via multiplying by 31.5

= 3.78kwh

Cost of that gas 3.78 @ 3.45p per kwh = 13p ( ignoring std charge for this exercise ! )


Therefore rounding up to 30p for 2 heats per day - to allow for a colder fill and still an estimate as winter mths would cost alot more, over 365 days a year that would cost 30p x 365 = £ 109.50

Even using my exact reading for one heatup from been preheated - still would cost £ 94.90 p/a

So my previous estimation of £ 80 saving using my Solar Immersion Device could be well under and the saving even for GCH users could be more than you think ....... food for thought

Please check my calculations and comment away..................... "

danesol

Update:- Based on a calculation on another thread for June's Gas bill - it appears that £ 8.00 a mth to heat a hot water cylinder twice a day for 2 hourly periods is more or less correct for my particular setting, therefore I recon' in the good PV mths you will be saving roughly and on average between 7-12pounds per mth ( min ) if you have one of these immersion switches fitted !

zeupater

danesol wrote: »

Update:- Based on a calculation on another thread for June's Gas bill - it appears that £ 8.00 a mth to heat a hot water cylinder twice a day for 2 hourly periods is more or less correct for my particular setting, therefore I recon' in the good PV mths you will be saving roughly and on average between 7-12pounds per mth ( min ) if you have one of these immersion switches fitted !

Only in very good months, so anyone considering that the saving would be for a typical month and therefore multiply the figure by 12 and use that figure as a typical saving, well they should consider that as being ... <cough> ... Bulls**t ... <cough> ...

Notably, there was no response to .... "So you're diverting somewhere around 1000kWh/year to the DHW then ?" .... logic check needed .... orrery has stated a saving based on around 1100kWh/year reduction in gas usage and our dedicated solar thermal averages 'diverts' somewhere around 1400kWh but this is limited more by usage than collection, So, when taking DHW heating (only) gas system efficiencies at (say) ~66% (?) with gas at (your) 3.45p/kWh, diversion of 1000kWh would likely displace ~1500kWh of gas, which would cost £51.75 (1500x0.0345) .... at orrery's diversion (say 660kWh diverted) call it ~£40 and at ours ~£75 .... we would save a little more due to very long primary circuit 28mm pipe runs, but those figures would probably describe a typical bracketed range for decent proportional-diversion annual savings from a ~4kWp array as being £40 to £75 ... of course, depending on a number of obvious factors, there's scope for more and the risk of less, but .....

HTH
Z

pinnks

I always find these discussions interesting. I have been a geek, recording monthly usage of gas and leccy each month since 2009. by using a diverter I save about £80 in gas over the summer months when the central heating is off and get my hot water on 99.9% of days. Less easy to estimate for the rest of the year but maybe £20?

So while mathematical assumptions and calculations of efficiency are fun, actual records speak volumes...:beer:

zeupater

pinnks wrote: »

I always find these discussions interesting. I have been a geek, recording monthly usage of gas and leccy each month since 2009. by using a diverter I save about £80 in gas over the summer months when the central heating is off and get my hot water on 99.9% of days. Less easy to estimate for the rest of the year but maybe £20?

So while mathematical assumptions and calculations of efficiency are fun, actual records speak volumes...:beer:

So, sticking with 3.45p/kWh, that's about 2900kWh (£100/0.0345) displaced, which, assuming a condensing boiler achieving 66% efficiency, probably represents around 1900kWh diverted from a 5.25kWp system ... ??

Mathematical modelling allows for a 'reasonable' or 'typical' target to be assessed, but I agree that actual records are useful ... however, danesol has a 2.88kWp system and reckons that the gas saving compared to a 3 year old condensing boiler would range from an original estimate of £80 to a possible high of £109.50 with a current modified estimate of £94.90 (all #398), which represents a huge 2750kWh/year of gas (yearly average of 7.5kWh/day) .... which must equate to somewhere around 1800kWh/year of diverted energy. not bad considering that the system generated 2.4MWh in 2012/13 (#330), so the proportional diversion must be effectively diverting all spare power, every day, which is a pretty amazing feat considering the number of days where generation must be far in excess of the thermal capacity of a standard build cylinder (#327) and the number of days where generation leads to little diversion at all .... that's why mathematics are pretty useful in some cases, especially ones where uncommonly large savings, specific makes & models along with purchase discount codes and prices are regularly repeated !

HTH
Z

pinnks

Don't get me wrong, I am more than happy to play with maths but sometimes the modelling needs factors which are difficult to estimate.

Anyway, the displaced amount looks about right for my system (sorry, can't find the energy today to pull out the actual numbers) but my diversion is only about 750kwh per year over the 3 years it's been in (2250kWh since 25 June 2013).

The difference on top of boiler (in)efficiency? Losses I assume in the 20m plus round trip of unlagged 28mm/22mm pipes between boiler and tank, which is less easy to model.