New PV solar install arranged, heating upgrade advice please - solar compatible hot water tank

edited 6 April 2022 at 1:34PM in Green & ethical MoneySaving
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wigwamwigwam Forumite
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edited 6 April 2022 at 1:34PM in Green & ethical MoneySaving
We are getting solar panels installed in about 12 weeks, a 5.3ish kw system from memory and  will also have a givenergy 9.5kw battery. We live in a 1930s semi on the south coast with a south facing aspect.
This is part of a larger renovation, and an extension to the side may require us to move the exisiting gas system boiler. Having moved from a flat this is all pretty new to us and so please forgive the ignorance around this all! We are however learning daily and willing to learn much more...
We have explored a ASHP but it is not for us at this time. It may be in the future but not just yet. 

We would like to upgrade our non immersion hot water tank as is currently looking worse for wear and is currently boxed in to a corner in the kitchen meaning part of the kitchen would need to be removed for access should anything go wrong. As we are ripping out the kitchen for a new one we figured this is the best time to replace the tank with something more efficient and which we can hopefully run with solar energy. Any suggestions for this would be most welcome.

We also as part of the renovations may have to relocate the current boiler - a baxi 600 system boiler. This is only 3 years old so we will try to avoid this. But if we do need to does anyone have any suggestions as to whether replacing with an electric boiler would be worthwhile with our solar set up. we plan to switch to octopus once installed. 

we explored getting a combi but would mean ripping up all the floors to get new gas pipes, and as we are trying to use less gas seemed to not be suitable for us at this time. 

Any advice / experiences  would be most welcome. 


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  • QrizBQrizB Forumite
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    wigwam said:
    We would like to upgrade our non immersion hot water tank as is currently looking worse for wear and is currently boxed in to a corner in the kitchen meaning part of the kitchen would need to be removed for access should anything go wrong. As we are ripping out the kitchen for a new one we figured this is the best time to replace the tank with something more efficient and which we can hopefully run with solar energy. Any suggestions for this would be most welcome.
    No doubt someone will be along with high-tech options, but (assuming you keep tanked HW) as a minimum get a tank with an immersion heater boss. Or ideally two bosses, one high and one low in the tank. This will give you the option of heating your electricity with surplus solar electricity.
    We also as part of the renovations may have to relocate the current boiler - a baxi 600 system boiler. This is only 3 years old so we will try to avoid this. But if we do need to does anyone have any suggestions as to whether replacing with an electric boiler would be worthwhile with our solar set up. we plan to switch to octopus once installed.
    If you've ruled out heat pumps, there's currently no cheaper general-purpose option for space heating than mains gas.
    Electric boilers are currently the worst option you could possibly choose, so pick something else! You'll need heating in the winter, when it's cold and dark and there's hardly any sun.
    N. Hampshire, he/him. Octopus Go elec & Tracker gas / Voda BB / Virgin mobi. Ripple WT2 member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 2.5kw inverter. 28MWh generated, long-term average 2.6 Os.
    Kinda busy right now but I try to pop back to the forum every so often. Drop me a PM if you need me!
  • edited 6 April 2022 at 5:20PM
    Reed_RichardsReed_Richards Forumite
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    edited 6 April 2022 at 5:20PM
    As a basic rule of thumb you cannot use solar power to meet your space heating needs.  The time of year when you need most heat is exactly the time when you will get very little solar power.  If you doubt this, ask yourself why is it cold in winter.  However your need for hot water will be pretty constant throughout the year and you can use solar power to heat your water (much of the time) in the sunnier parts of the year.    
    Reed
  • paul991paul991 Forumite
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    probably  best to  go for any  well insulated tank with 2 coils and  2 immersion bosses then you will have the flexibility for what ever you decide later 
  • EctophileEctophile Forumite
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    If you're getting a new tank, fit an immersion heater.  If nothing else, it's a handy backup when your boiler goes wrong.

    You can also decide whether or not to buy a solar diverter and get free hot water in the spring and summer.
    If it sticks, force it.
    If it breaks, well it wasn't working right anyway.
  • wigwamwigwam Forumite
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    Thanks all, so to sum up - avoid an electric bolier, isn't a bad idea to get a tank with 2 immersion heaters. Does anyone have any recommendations of tanks or diverters? Sorry - extremely new to this and do not want to make expensive mistakes

  • edited 6 April 2022 at 7:49PM
    QrizBQrizB Forumite
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    edited 6 April 2022 at 7:49PM
    wigwam said:
    Thanks all, so to sum up - avoid an electric bolier, isn't a bad idea to get a tank with 2 immersion heaters. Does anyone have any recommendations of tanks or diverters? Sorry - extremely new to this and do not want to make expensive mistakes

    There aren't that many tank manufacturers. Most have their off-the-shelf models but also do custom ones.
    My current tank is a Gledhill: https://www.gledhill.net/
    Take a look at the options on their website, it will give you an idea of what is possible and what isn't.
    Stainless cylinders used to be a premium option, but recently it looks like prices have swapped?
    N. Hampshire, he/him. Octopus Go elec & Tracker gas / Voda BB / Virgin mobi. Ripple WT2 member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 2.5kw inverter. 28MWh generated, long-term average 2.6 Os.
    Kinda busy right now but I try to pop back to the forum every so often. Drop me a PM if you need me!
  • Reed_RichardsReed_Richards Forumite
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    If you were thinking you might want a heat pump at some time in the future then you would need a special tank with a much longer internal coil (which therefore has a larger surface area).  This is so the water in the tank can be heated in a reasonable time with relatively low temperature water, exactly the same reason that generally requires you to get larger surface area radiators to work with a heat pump.
    Reed
  • paul991paul991 Forumite
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    i use a https://solarimmersion.co.uk/shop/solarimmersion-solar-pv-surplus-energy-manager/
    mines now 7 rears old and has 2 outputs ive had no problems with it
  • edited 7 April 2022 at 9:10AM
    mickyduck55mickyduck55 Forumite
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    edited 7 April 2022 at 9:10AM
    paul991 said:
    i use a https://solarimmersion.co.uk/shop/solarimmersion-solar-pv-surplus-energy-manager/
    mines now 7 rears old and has 2 outputs ive had no problems with it
    I have had two of these both failed after about a year.. had one repaired for about £70 failed again.. bought Solic 200 about 5 years ago no problems.. Not saying specifically there is anything wrong with it but my experience is not good.
    If anyone wants my old one its still in my garage probably an easy repair just cover postage

    3.995kWP SSW facing. Commissioned 7 July 2011. 24 degree pitch (£3.36 /W).
    Solar Immersion installed May 2013, after two Solar Immersion lasting just over the guarantee period replaced with Solic 200... no problems since.

    13 Feb 2020 LUX AC 3600 and 3 X Pylon Tech 3.5 kW batteries added...
  • mickyduck55mickyduck55 Forumite
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    Re the original question destratification pump would be on my wish list for features in a new tank rather than 2 immersions or am I missing something obvious  
    3.995kWP SSW facing. Commissioned 7 July 2011. 24 degree pitch (£3.36 /W).
    Solar Immersion installed May 2013, after two Solar Immersion lasting just over the guarantee period replaced with Solic 200... no problems since.

    13 Feb 2020 LUX AC 3600 and 3 X Pylon Tech 3.5 kW batteries added...
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