Sand battery heater

tetrasect said:
Like I said earlier, 1 bucket of sand going from 20-450 degrees has around the same energy storage capacity as 2 buckets of water going from 20-80 degrees, and the water only weighs slightly more (storage capacity of 1.6kg sand = storage capacity of 2kg water).

So to match a 150L geyser holding 150kg of water you would still need 75L of sand which weighs 120kg.

Don't see that going on top of any cupboard...
Click to expand...
Never said I want to put it on a cupboard.
 
BBSA said:
About 5kwh.
Click to expand...
So you'd need about 70 liters of water.
If heated to a more safe 200 degrees, you'd need 75 liters of sand.
If heated to 450 degrees, you'd need around 32 liters of sand.

For the water, you could 75L tub for 45 bucks:
www.rashidaplastics.co.za

75L Jumbo Tub | Rashida Plastics

www.rashidaplastics.co.za www.rashidaplastics.co.za

For the sand, if you wanna use a 35L potjie pot, it will cost about 4,000 rand.

bestduty.co.za

Best Duty Pot 3-Leg #14 - Best Duty

Best Duty Pot 3-Leg #14 - Traditional quality, heavy duty and very robust 3-legged pot for the best potjie experience. Oil-cured & ready to usePrice includes VATPrice excludes deliveryServes: 50-60Volume: 34.5L
bestduty.co.za bestduty.co.za
 
tetrasect said:
So you'd need about 70 liters of water.
If heated to a more safe 200 degrees, you'd need 75 liters of sand.
If heated to 450 degrees, you'd need around 32 liters of sand.

For the water, you could use 3 of these polypropylene buckets at 42 bucks each and the water is free:
foamy.co.za

Blue 25L Bucket + Handle + Lid - Foamy

25l Tamper-Evident Bucket—a sleek solution with a breakable tag for unmistakable proof of product integrity. Comes with a handle for easy carrying. Can be used for and more: Food Storage Craft and DIY Projects Cleaning Supplies Pine gel Gardening Personal Care Pet Care Sampling Office...
foamy.co.za foamy.co.za

For the sand, if you wanna use a 35L potjie pot, it will cost about 4,000 rand.

bestduty.co.za

Best Duty Pot 3-Leg #14 - Best Duty

Best Duty Pot 3-Leg #14 - Traditional quality, heavy duty and very robust 3-legged pot for the best potjie experience. Oil-cured & ready to usePrice includes VATPrice excludes deliveryServes: 50-60Volume: 34.5L
bestduty.co.za bestduty.co.za
Click to expand...
I already have a potjie.
 
tetrasect said:
Doesn't matter whether you're heating sand, water or strawberry milkshake.

You get out what you put in.

Roughly.

So if you have 10kwh of excess power going into your water during the day, then at night you will get the equivalent heating output of running a 1000W electric heater for 10 hours.

If you have 5kwh of excess power then you get the equivalent of running a 1000W electric heater for 5 hours, or a 500W heater for 10 hours.
Click to expand...
What if it’s 10 000W for 1 hour?
 
Have a look at the sill planters made of stone - easier to fit and you could add multiple of them.

With that size pot I would say why are you not testing already ....
 
By 10am geyser is hot. Battery is full.
Only solution for solar is more batteries.
In the winter I run the underfloor heating all day off the panels then it turns of at night. Very thick tiles so they stay warm till about 5am.
 
I lose about 50% on rainy days. So geyser is hot by 12pm.
That is not using the battery.
Also one has to change habits.
Dont use hot water for baths in the evening.
Insulate the geyser and pipes properly this makes a big difference.
 
BBSA said:
The actual energy you get out depends on the efficiency of the storage and retrieval process. Some energy is typically lost due to heat loss, especially when using thermal storage systems.
Click to expand...
Heat loss is what you want in this case ie if sand battery is indoors you lose nothing as that was its purpose to heat the home overnight
 
Thugscub said:
I lose about 50% on rainy days. So geyser is hot by 12pm.
That is not using the battery.
Also one has to change habits.
Dont use hot water for baths in the evening.
Insulate the geyser and pipes properly this makes a big difference.
Click to expand...
Sure you can use hot water at night , just have a timer on it so it doesn't heat with eskom leave it cold to heat via solar next day

Some that use some water at night and some next morning say they heat to 70 thus use less at night ir more cold water to get desired temp

And then the left overs may be warm enough for a morning shower still
 
BBSA said:
I've been thinking about using a geyser element powered by spare solar energy to heat sand in a bucket, which could then be used to warm a small room later. It sounds like a promising idea, but I'm unsure about how long the element would last under such conditions. Has anyone tried this or have any thoughts on the longevity of the heating element?
Click to expand...

What happened? I'm guessing the heating element housing couldn't provide enough insulation and the cable sleeving started melting?
 
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