One for the Solar and Battery addicts

[Robert Clark]

What do you make of this ?
Not for the motorhome, but for your house

 

[autorouter]

Not for the motorhome,

Why not? Let's play with a few numbers. One of those units stores up to 5.5 kWh of heat.

500 watts of solar is quite possible on most motorhomes if there's a good reason. This sounds like a good reason. On a good summer day in the south, you could get 400 watts for 8 hours = 3200 watt-hours = 3.2 kWh

I estimate that a shower would require 20 litres of water at 60 degrees C. You'd be mixing it with cold water, so you'd get more than 20 litres through the shower head.

How much heat energy is needed? Well, 1 litre of water needs 1.163 watt-hours to heat it up by 1 degree C.
20 litres heated by 50 degrees (from 10 to 60 degrees) is
20 x 50 x 1.163 = 1163 watt-hours = 1.163 kWh.

So 3.2 kWh of stored heat energy would be enough for two showers, and the washing up as well.

One of those units doesn't take up much more space than a gas water heater. The downside of course is the same as anything that depends on the sunshine, it is variable. And you mostly want heating when the sun isn't shining. But it seems crazy to use gas to heat water when you've got the fans on full blast as the sun blazes down on a long hot day.

 

[Snowbird]

KIS. Why go to all that trouble and expense when a simple immersion heater used as a dump would do the same job and a damned site cheaper.

 

[Reallyretired]

I thought he'd dribbled on his shirt front. Later was clear it was the shadow of the clip on Mike.

 

[Vansflyer]

Love the idea but what about the cost, when does it break even?

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[Richard n Ann]

KIS. Why go to all that trouble and expense when a simple immersion heater used as a dump would do the same job and a damned site cheaper.

Yes, with a vacuum flask wall arrangement like the gel stuff has, what's to say the standing heat loss would be any higher. But perhaps the gel stores more heat, I know it takes a lot of heat energy to melt ice so changing state might be the key.

 

[Clarky]

Looks impressive.
I guess in the end it all comes down to cost v savings.

Richard.

 

[SandraL]

https://learn.openenergymonitor.org/pv-diversion/introduction/choosing-an-energy-diverter.md

The above is a diy solar diverter. Very cheap to make. Doesnt have the visual readouts. I have used mine for last 3 years to divert surplus energy into either the immersion heater in summer or an oil filled radiator in winter.
Clever bit of the video to me is the stuff that stores the heat. More detail on the material would be good, but I guess thats his business idea.

 

[Ivory55]

I guess it’s an down to cost, but I have thought before why not have a large tank under the floor which is heated by solar in the summer and used to heat the property in the winter.

 

[Robert Clark]

I guess it’s an down to cost, but I have thought before why not have a large tank under the floor which is heated by solar in the summer and used to heat the property in the winter.

That technology is already in use, but it takes up lots of space, whereas the Sunamp it tiny

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[tacr2man]

Wouldnt something like this fitted with immersion element achive pretty much same thing ?

 

[olley]

Years ago I did a kitchen for a customer, and while I was there he took great delight in explaining his heat store.
It was the floor of his conservatory, this was a solid block of insulated concrete some 6' plus deep, his idea was in the summer it would heat up, and stay warm in the winter.
No idea if it worked.

 

[autorouter]

KIS. Why go to all that trouble and expense when a simple immersion heater used as a dump would do the same job and a damned site cheaper.

The problem with the simple immersion heater in a tank is that on a dull/winter day the water is warm but not hot. It's a breeding ground for bugs, you're likely to get things like legionella in the water.

This phase change gel melts at high temperature (I don't know what temperature, he doesn't say, but it's going to be around 80 degrees C I would guess). The water is cold, and quickly heats up to 60 degrees as it passes through the gel. This is on demand, so no hot water is wasted. Because it uses the heat of melting, it stays at the melting point most of the time, so the temperature stays high.

 

[Lenny HB]

Anyone notice the big mistake the presenter made? - He said saves 75% of your gas bill over a year, should have said saves 75% of the gas use for water heating which won't be much compared to the heating bill.
Interesting but can't see it ever going to pay for itself.

 

[olley]

Melts at 58c according to their website.
https://acarchitects.biz/self-build-blog-sunamp-heat-batteries/

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[DBK]

Anyone notice the big mistake the presenter made? - He said saves 75% of your gas bill over a year, should have said saves 75% of the gas use for water heating which won't be much compared to the heating bill.
Interesting but can't see it ever going to pay for itself.

Exactly my thoughts. You can get solar hot water installations (vacuum tubes on the roof usually) which also claim to meet most of your hot water needs - but they only mean the hot water coming out of the tap. They do next to nothing in winter for the central heating. A big thermal store (giant hot water tank) will allow central heating water to be heated but again, not much use in winter. If you want to have solar powered heating a ground source heat pump possibly in connection with a big battery might be more effective but generally the house needs designing from the ground up for this sort of solution - underfloor heating and high levels of insulation.

 

[autorouter]

If you want space heating you could use a diverter unit to send the surplus solar electricity to an electric storage heater. These heaters are becoming more popular as people want to cut out fossil fuels and switch to renewable electricity, in places like Germany. But it's the same old problem with solar - who needs heating when the sun is shining?

 

[Robert Clark]

Melts at 58c according to their website.
https://acarchitects.biz/self-build-blog-sunamp-heat-batteries/

Think thats referring to the magic material inside, ie the temperature required if using an external heat source to feed into the unit, not the melting point of the unit itself

 

[autorouter]

Just looked at their web site, and they do a wide range of these batteries, not just these domestic water heating ones.

They do small units with double heat exchangers for cars and buses to store engine heat, for quick warmup the next day for example. Also does units for electric cars (which don't have cabin heating from a water-cooled engine of course) to keep warm in winter. Saves using vehicle battery for cabin heating so keeps winter range the same as the summer range. Presumably heated up from the charge point so will use your house electricity.

These units will I suspect have wide usage in motorhomes in the future. They have a very large number of cycles, they are talking about 35 or 50 years accelerated life tests and they have hardly deteriorated at all.