Sonnen LI battery packs.

[pianotuna]

This looks possible for an RV in the 4 to 8 KWH pack.

https://www.sonnenbatterie.de/en-us/sonnenbatterie


Power Unit
Continuous output:
(AC) 3,000 W – 8,000 W

Dimensions (in) W/H/D 4 - 8 kWh: 26/51/14

Dimensions (in) W/H/D 10 - 16 kWh:
26/71/14

Backup power capability

Usable capacity:
4 kWh - 16 kWh (in 2 kWh steps)

I can't find a price.

[GordonThree]

it wouldn't really make sense in an RV, the infrastructure required is too complicated for Elkhart to figure out.

On a home though, you would have a hot water storage tank with dual heat exchangers in it. one loop for solar, another loop heated by on demand boiler that also serves a hydronic system. add a series of valves and sensors, etc to manage it all. rooftop might only get the water to 100F degrees, but that means the on demand only needs to put another 30-40F in to reach a hot delivery temperature.

[BFL13]

It is useless to heat up water all afternoon and then by next morning when you want that hot water to shave, the water is now cold from sitting there un-heated over-night.

[pianotuna]

Hi MrWizard,

I have seen a "combo" panel that does water heating. I've never thought it would make much of a difference because showering in water that is below about 120 F (49 c) is on the coolish side for me.

If the "coolant" were hooked up to a heat pump--then it would make more sense.

[GordonThree]

MrWizard wrote:
I wonder about putting a DIY thermal energy transfer system, water piping?
Under the panels, use it to pre-heat the water for the RV while cooling the panels to make them more efficient

I've wondered why big fixed solar installs don't do this. roof covered with panels soaking in the Sun all day, put a snake of copper tube on the back and use it to heat some water.

[MrWizard]

I wonder about putting a DIY thermal energy transfer system, water piping?
Under the panels, use it to pre-heat the water for the RV while cooling the panels to make them more efficient

[GordonThree]

Better batteries are only part of a solution, whatever the problem is. So many things today are super wasteful with energy usage, because hydrocarbon fuels are cheap and plentiful, either for direct consumption or indirect (electrical generation.)

Anything that gets hot while operating needs to be better engineered, so it no longer gets hot. Doesn't matter if it's a computer processor, a light bulb or a truck engine. All that heat is wasted energy.

Fix the waste, reduce the energy needs, and reduce the need for a super battery, either in a device, a vehicle or a roof-top solar panel.

[pianotuna]

Hi Gordon,

They did not speculate about what is around the corner. They did review items that are in production (such as the salt water battery), and items that are working in the lab.

Cost of solar and wind is now below that of coal or gas plants.

[GordonThree]

Ahhh the super battery, perpetually just around the corner for the last 30 years at least... Just like commerical nuclear fusion and flying cars.

Either the physics is super hard (like fusion) or there's not really a big demand (flying cars)

Gasoline (and diesel) remain our best battery and until gone, there's not going to be real demand for a truly impressive battery.

The companies that have trillions invested in multi gigawatt gas, coal and oil power plants as well as the massively lossy transmission line infrastructure across the globe don't want you storing solar power at home. Germany has done good to buck that trend but they're a tiny influence to the global scale.

[pianotuna]

Nice program on Nova last night about batteries and what may be ahead.

[GordonThree]

brulaz wrote:
Hate to imagine what 940 lbs of LiPO4 battery would cost.

If you're spending 2-3 MILLION on a luxury rig, a battery the price of a luxury sedan isn't out of the realm of possibility.

Nevertheless I agree 🙂

Apparently Elon is already at break even with his new Panasonic lithium factory in Nevada... Hopefully he'll be able to give the Chinese competition in the race to the bottom for pricing on these things.

[brulaz]

Hate to imagine what 940 lbs of LiPO4 battery would cost.

[GordonThree]

I didn't see the small battery you pointed out. I came across this:

Battery unit:
24 kWh (repeatable to 240 kWh)
LiFePO4 battery
Weight: 940 lbs (approx)

940lbs, GULP! I suppose that would be nothing for a big Class A or Super C to haul around, with a 10+ year lifespan, build it into the frame somewhere, doesn't need to be easily accessible. 24 kWh of power would let you get rid of the propane system all together, including the bulky tanks. use electric for everything.