Hi,
I have a conventional PV system with a 'Solar Immersion' fitment added (Google 'Solar Immersion' for details). I have a conventional domestic hot tank with a top fitted immersion. I went for a 1Kw extra long heater (purchased from Solar units? on the internet), I chose a 1KW unit as this works when perhaps weather conditions are allowing the PV unit to produce 1Kw and also when using power for domestic use often there is 1Kw + spare to power the immersion as well as the appliance being used.
It heats up HWater quickly to a very high temperature, but I am not sure how much of the tank gets heated, some users suggest fitting a pump helps circulate hot water in the tank , improving the performance, but to date I am happy with the quantity of hot water produced.
My domestic unit produced 490 units in May and last quarter 970 units, this is down on previous years due to poor weather, I shall get a payment from nPower of about £190 soon.
Hope this helps, let me know if you want more info.
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