How much hot water do I need?

[Adam2]

Thanks @Stones for sharing your setup & experience with that - encouraging! It's 

 

Re Solar - we're planning to cable for PV as we have a flat roof area which could accommodate this but given the long time for a return on investment we'll defer the installation. If electricity keeps going up and panels come down it may make sense in a couple of years as we do have an electric car and ASHP so should be able to utilise a lot of what we would generate. 

 

Am chatting with a plumber at the mo that is quite pro solar thermal but I need to see some costs and decide if this has any real benefit/return on the investment. Would prefer simplicity vs saving £100 a year for 20 years to get payback!

 

[SteamyTea]

  On 21/10/2021 at 09:13, Adam2 said:

we're planning to cable for PV as we have a flat roof area which could accommodate this but given the long time for a return on investment we'll defer the installation

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You can get a 300 W PV module for £135 on eBay.  That is 1.6m² of coverage.

B&Q will sell you, for £1000, a rooflight that is 1.5m² of coverage.

 

How cheap do you want PV to become?

[TonyT]

I purchased 10x250 watt panels £50 each.?

[Adam2]

  On 21/10/2021 at 09:26, SteamyTea said:

How cheap do you want PV to become?

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I'll run the numbers again to look at payback based on what we could likely utilise - with ASHP and an EV this may be OK but I guess the EV will be at work much of the time during the day in the week so would rely on other things using the sun's energy - can of course put into UVC. Will see what a box of bits for solar will cost ? 

 

For now though will have cables and roof penetration for this at least in our plans and a UVC with a suitable coil so can add in later. More pressing dramas now like a plumbing co that will agree to have a ashp system with cooling of the slab!!! Apparently Panasonic and Mitsubishi do not "warrant the process" whatever that means as their units would just be chucking out cold water like they are supposed to do and the rest is someone else's responsibility!!!! argghhh May have to just get a regular plumber to follow my instructions and not have them responsible for the overall system performance

[TonyT]

Make sure you allow a cable from the immersion heater area to the PV diverter location too, or a few points incase you fancy utilising the power for various other things

[SteamyTea]

  On 21/10/2021 at 11:54, Adam2 said:

I'll run the numbers again to look at payback based on what we could likely utilise

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Add in a carbon cost into the spreadsheet.

A penny a kWh would be a high starting point, at 0.15 p per 1 kWh would be about today's cost.

Edited October 21, 2021 by SteamyTea