Immersion Heater - PV electricity

pauldreed

I have solar panels fitted which generate up to 3.3kw, but most days it's 1 to 2KW.
I want to heat my water with that power, and have sourced a 1kw immmersion heater element (it was designed for boats!) with a suitable 2 1/4" BSP thread, but it is only 11" long.
If I mount this at the top of my water cylinder, would it eventually heat all of the water in the tank - or just the top 12" or so? (hot water rises).
Anyone any experience of immersion heaters???

albyota

Hi pauldreed, a 1kW element would only just about warm the top of the tank, anyway assuming you are grid tied, there is no way of directly connecting it to the panels, so you would be better off just setting your standard immersion heater to switch on for an hour at mid day

pauldreed

albyota wrote: »

Hi pauldreed, a 1kW element would only just about warm the top of the tank, anyway assuming you are grid tied, there is no way of directly connecting it to the panels, so you would be better off just setting your standard immersion heater to switch on for an hour at mid day

Yes I am grid-tied, but want to try this different approach if I can.
Would it only 'warm the top of the tank' because (as I suspect) - hot water rises and the heat would not permeate downwards?
I was anticipating it to be heating for 4-5 hours a day, and then 'topped up' - if necessary at evening time by the gas boiler.

paceinternet

You would need to circulate the water in the tank from top to bottom using a pump. They are available from Companies like Grundfoss, but not cheap. Or you could get a different tank with immersion heater connections lower down.

However, do you mean the solar pv generates 1-2 kw over a 24 hour period?
Or is it running at 1-2 kw per hour?
Is there enough current generated to power the immersion heater?

pauldreed

paceinternet wrote: »

You would need to circulate the water in the tank from top to bottom using a pump. They are available from Companies like Grundfoss, but not cheap. Or you could get a different tank with immersion heater connections lower down.

However, do you mean the solar pv generates 1-2 kw over a 24 hour period?
Or is it running at 1-2 kw per hour?
Is there enough current generated to power the immersion heater?

1 - 2 kw per hour, hence using a 1kw element