New PV solar install arranged, heating upgrade advice please - solar compatible hot water tank 6 April 2022 at 1:28PM edited 6 April 2022 at 1:34PM in Green & ethical MoneySaving 29 replies 657 views

wigwam

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. 

QrizB

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.

Reed_Richards

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.    

paul991

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 

Ectophile

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.

wigwam

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

QrizB

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?

Reed_Richards

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.

paul991

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

mickyduck55

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

mickyduck55

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