Dual Hot Water System

[Chrisgr31]

In December we had solar panels installed. The return on them is best when you can divert unused power you generate into an immersion heater for your hot water, rather than exporting to the grid. However in our case we can't do that as we have a combi gas boiler so no hot water tank.

So I was wondering if I could install a hot water tank in the loft with an immersion heater and run an additional supply to the bathroom and kitchen which are directly below. Or as its possible what the costs would be. Guessing piperun of 20 ft to bath so 20ft cold water up, 20 ft hot water back down, then further 20ft run to kitchen sink below. What sort of cost am I looking at just a guide price will do as its assessing practicalities of it.

Failing that is it possible to feed it in to the existing hot water system?

[NorthDave]

I think you could install a mains pressure tank (like a megaflow), as far as the combi is concerned it would think of it as another radiator. I have no idea of costs but the tank alone is about £700 to £800 I think, depending on size.

[CoolHands]

yeah but how many years would your 'savings' take to pay back the cost of installing new tanks etc. Probably not worth it.

[ARH]

I have solar thermal for my hot water. it heats up the tank of water and then feeds it through the combi boiler to heat it up to full temp if needed. I am sure you could do the same thing but heat the water from your solar PV instead

[Chrisgr31]

Thank you some interesting options, and yes Coolhands I would have to find out what the pay back period would be. First issue with that is to find out how much solar power I don't use, but I suspect its fairly significant.

[Zingari]

I've got solar panels on the FiT scheme. Whilst I've got a hot water tank the option for me was to have a 'heat pad' fitted to the tank.

I thought this was going to be fed via the solar panels but it actually plugs into the mains? In a roundabout way with the meter being slowed down in the sun and the generated meter providing me a rebate I suppose it is a by product of shoot of the solar panels.

Jury is still out on the benefits v cost though.

[AW10]

I think the average figure is that you use 30% of what you generate and the rest you export. That matches my experience - generating 4000 kWh/year and reducing the bill by 1200 kWh/year.

An immersun/solar iboost to control the diversion of excess PV generation with cost between £250 and £500 depending upon which one you chose and whether it's a DIY install or needs a sparkie. If you need plumbing mods such as an extra tank I suspect the mods will have a very long payback time so doing it for financial reasons may never pay off. But if being green appeals it's harder to quantify.