Solar powered hot tub

debt_mountain_2

I have a hottub and i have a new house with solar panels. 

hot tub draws 2000w when its heating which is around half an hour 3 times a day in the summer and 5 times in the winter.

On a clear sunny day My panels generate 1200w in the summer and 850w in the winter 

i pay around 30p per unit for electricity and any unused units go back to the grid and i get 5.5p for them ( total con)

so i have an idea.

i got a burst lay z spa for free. The heater unit in the lay z spa has 3 x 700w elements so if i plumb the lay z spa heater unit ( but disconnect 2 of the elements)  into my hot tub and use the lay z spa timer i can set it to run during the day only it will run 3 times as long as my main hot tub heater but the majority of the time it will be free ( well 5.5p units i wont get paid for instead of 30p) 

if the lay z spa heater is on and i put on my washing machine then it will be 30 units so still some full price electric will be used

Sums

summer

hot tub heater - 3 x 30mins x 2 kw x 30p/kwh. = 1.5 hours x 60p = 90p

winter 5 x 30 x 2 hw x 30p /kwh = 2.5hrs x 60p = 150p

lay z spa heater - 3 x 60mins x 0.7 kw x 5.5p/kwh. = 3hours x 3.85p = 6.93p

winter 5 x 60 x 0.7 kw x 5.5p/kwh = 5 hrs x 3.85p = 11.55p

Way less than 10% running cost 

woohoo

Neil_Jones

You haven't factored in your standing charges for your electricity.  So it's more than 10% running cost.

Of course it would be far cheaper not to use the hot tub in the first place   They are power hungry things.

debt_mountain_2

Neil_Jones said:

You haven't factored in your standing charges for your electricity.  So it's more than 10% running cost.

Of course it would be far cheaper not to use the hot tub in the first place   They are power hungry things.

Yeh true but the hottub saves me having a shower every day.

The standing charge is a daily theft tax ( doubled for some reason ) that has to be paid whether or not i use any electricity or not so i dont think it changes 

IvanOpinion

I don't think you are comparing like for like.  You haven't factored in any solar usage in relation to the hot tub elements but assume that all Lazy-Boy element usage will be solar?  Also you have only factored in the Lazy boy running twice as long (you said 3 times as long). 

To make the comparison more accurate you would need to assume that your hot tub is drawing about 60% from your solar.


One other point, you referred to the 30p vs 5.5p as a 'total con'. A total con would be giving you nothing back, but you have to factor in that, while you are exporting, you are not paying for their infrastructure that they are allowing you to use, nor for the cost of the many legislative, regulatory and managerial requirements that the energy suppliers have to meet.

debt_mountain_2

I agree ivanopinion
but even if the costs of running with the lazy spa are quadrupled its still less than half the cost but the main reason for trying this cost cutting experiment is mainly for fun and because i can and to keep my brain active.

the 30p to 5.5p con is poor, i sell them ( they take - i dont have a say in what they pay me) a unit for 5.5p and they then sell it to my neighbour for 30p. So each unit has a 25p infrastructure cost. Plus they just doubled the cost of a unit but didnt double the feedin payment. 

Me generating this feed in also has an infrastructure cost to me , 

and the recent doubling of the standing charge was explained to consumers as the infrastructure cost and future investments

so they need to do a lot of work to justify the con to me

IvanOpinion

debt_mountain_2 said:

Plus they just doubled the cost of a unit but didnt double the feedin payment. 

I agree with you on this.  If they have massively increased the cost of electricity units then I would expect it would only be fair to see an increase in the payment for export units.  Although I suspect that is just wishful thinking on my part.

Ergates

debt_mountain_2 said:

Neil_Jones said:

You haven't factored in your standing charges for your electricity.  So it's more than 10% running cost.

Of course it would be far cheaper not to use the hot tub in the first place   They are power hungry things.

Yeh true but the hottub saves me having a shower every day.

The standing charge is a daily theft tax ( doubled for some reason ) that has to be paid whether or not i use any electricity or not so i dont think it changes 

Aren't you supposed to shower *before* going in the hottub.  Otherwise you're just sitting in weeks old dirty bathwater.