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Comment by adamcharnock | Hacker News Reader

On a smaller scale, I’m on off-grid solar and I potentially have 20kWh excess generation a day on solar (+/- 100%). Any exciting ideas regarding what I could shove that into?

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Time shifting of existing needs is probably the most effective use.

Do you have hot water storage? Time it to run down and recharge when you have excess. There are commercial products that do this semi-automatically. You can also get hot water taps that replace tea kettles that work on a similar principle.

If you have air-con or electric heating then run it to store heat and/or cool in a thermal mass.

Organise your day to run washing machines etc. at those times.

Phase change of water to ice can shift cooling loads if you have warm nights.

Plus electrify anything you have that currently burns fuel.

I'd love to see way more effort and subsidies going into thermal batteries. We don't need to invent any new technology since it already exists. Thermal batteries can use pretty mundane, low impact materials, so the downsides of mining and manufacturing scale of chemical batteries don't apply. Thermal batteries can't solve the problem on their own, but we can build them now at huge scale pretty cheaply.

In order of impact (since you say you're off-grid which implies you have batteries or storage):

1) Get an EV if you don't already have one: 20 kWh is about the perfect excess capacity to convert.

2) Upgrade fossil-fueled appliances in your home to electric appliances, like to induction cooktops and heat pumps. (Do you have a gas range? They're so poor at heating efficiency and pollute your living space.)

Disclaimer: This suggestion is not a cheap idea though perhaps something to think about. As a matter of water storage and preparation, one could use solar power to pump water into one or more elevated water tanks during the day then let it run into a ground level or underground tanks at night passing through some turbines. There are some hobbyists on youtube that do this and produce between 500 and 2000 watts continuous, depending on volume and flow rate. This is may be useful if your power consumption is higher at night. Some math should be done in advance to determine the volume of water required to sustain the desired flow rate for most of the night and to determine the size and number of tanks and of course the overall cost.

There is likely no harm in keeping extra water around for the rule of 3's. [1]

[1] - https://www.trailhiking.com.au/safety/survival-rule-of-three...

You could boil water to use it as an alternative to chemicals for dealing with weeds.

>Any exciting ideas regarding what I could shove that into?

May not be "exciting", but storing for future/dark use would be good :)

You could sell it by opening a charging station. People would love to charge their cars with solar energy.

Interesting! Perfectly fits my question.

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