Hydrogen-producing rooftop solar panels nearing commercialization | Hacker News Reader

Hydrogen-producing rooftop solar panels nearing commercialization

pv-magazine.com

11 pointsdanboarder34 comments

I’m not convinced that building a combined unit for solar and hydrogen production is more beneficial than having separate components. You are inherently limited by the lifetime of the least durable component. Having them be separate lets you replace whichever component fails without needing to replace both.

The electricity for a rooftop solar panel can easily be run to a ground-based hydrogen generator. The hydrogen component surely increases the weight of the unit to more than a plain solar panel so installation would be harder and overall weight on the roof greater. If the hydrogen generator needs maintenance, it would be much easier for a ground-based unit than rooftop units.

Or the combined units could just be repairable instead of being replaceable?

> They claim it produces 250 liters of hydrogen per day

"Mole of any gas under normal conditions - ~300K, 1 atm - occupies 22.4 liters of volume (Avogadro's law)". Mole of hydrogen (H2) has the mass 2 grams. 250 liters corresponds to 250 / 22.4 = 11.16... moles = 22.32... grams. So the unit above makes ~22 grams of hydrogen per day.

A better article with more data would certainly be welcome.

15% is a little better than i expected. Is this for situations where you have so much excess capacity that batteries don't make sense? Why would someone install so much excess capacity though? At that point it probably makes more sense to use a molten salt solution?

Batteries make sense on the scale of days. My coming solar installation will yield ~250% of my usage may-September and 10% of my January usage. I’d rather store the summer excess production until winter.

Having not run the numbers, that sounds like it would never be profitable for a home installation to solar->hydrogen->storage for months->burn as needed. Lot of capital on the various required components.

Edit: I guess if you wanted to go fully off-grid, this would be a useful option.

I also think these solar-hydrogen systems will benefit from scale as the marginal cost of production drops. Examples like the cost of producing microwave ovens, for example, have dropped from thousands to less than one hundred dollars with economies of scale. As a manufacturing sector of competing parts suppliers emerges, we will see price come down to benefit home owners.

I guess the price of adding additional solar panels was pretty small compared to the labour and inverter costs or why is it so overdimensioned?

I don't think private homes will have their own hydrogen production and storage facilities, this is more for industrial scale facilities.

> I don't think private homes will have their own hydrogen production and storage facilities

May be you right, but people already use compressed air storage's to store energy at private homes.

Sure, they are low pressure, for safety.

Do you have any examples? I know these CAES are sometimes used on an industrial scale but I haven't heard of small scale solutions for individual homes.

You just looking wrong direction. Low pressure solutions are not shown on TV, because on highly concurrent market, need something more distinguished.

But LOW pressure really easy achievable with plumbing technologies.

It would be good to have some examples, to prove that this actually exists.

Are you joking? Just visit nearest building market (supermarket) and ask, how large pressure could withstand their tubes, furniture, etc.

And learn physics, your life will change for better.

My knowledge of physics is alright. Regular stores don't use pressurized air to produce electricity. They use electricity directly for obvious purposes.

Your knowledge of physics is near zero.

With good knowledge you will know, that in typical auto service electricity is not used, they use pneumatic elevator, pneumatic drill machines, etc.

Usually, in office environments, pressurized air created by electric compressors, but large share of mobile services use compressors powered directly from combustion engine, and every modern semitruck include compressor and could provide pressurized air in limited amounts.

In your previous reply you were talking about supermarkets, you're changing the goalposts by suddenly talking about auto services. We're not talking about pneumatic equipment, that is just not relevant for households. We're talking about storing energy to use it at a later stage as electricity or heat. These are the relevant use cases for households. Pressurized air to electricity on a household scale is in its infancy and there are (almost?) no commercial solutions available at this time.

You're funny. You don't know anything beyond your nose and trying to make University level conclusions with so tiny knowledge.

If you want to continue this talk, write at least 5 most used cases of household energy usage. Not your energy usage, but how other people use it.

You can't produce any examples so you resort to personal attacks, it's a bit lame I must say. Since you couldn't produce any examples, I looked it up myself. [0] The conclusions are summed up in my previous reply to you. I do suggest you check out the article and its sources, next time this subject comes up you'll hopefully be a bit better informed.

https://www.lowtechmagazine.com/2018/05/ditch-the-batteries-...

I don't have target to convince you, I just share you truth.

But sure, you could use garbage sources, and feed mind with infogarbage, if you wish.

And unfortunately, you behave rude, so I will not continue talk in this style, until you will answer my questions.

I don't get why you keep digging a hole for yourself. That source contains about 30 references to scientific articles.

scientific articles don't equal to truth.

Back to moving the goalposts I see. You claimed it was infogarbage, which it quite clearly isn't. Of course scientific articles don't equal truth, if they did we wouldn't need to improve upon them. You have made a lot of baseless claims that don't stand up to scrutiny, I think it's about time to swallow your pride and admit you were wrong.

Where? In Germany I never heard of this. How much energy can these store?

I've hear, in France air energy has wide adoption, even few decades ago, before electricity, exists compressed air ring in Paris.

In Germany still exists lot of recognizable buildings, where stored methane. Some of them converted to culture/arts centers, because their specific design, not suitable for living or work (large cylinders).

In some countries you can sell your excess solar electricity at decent prices, this may have been a part of the motivation.

That’s the case here and currently the economics are in my favor (I’ll probably be able to sell for more than I buy). That however, can change swiftly.

If you live somewhere the seasonality index is high (2ish), you can either buy winter electricity (or use a generator for off grid) or you can run a third of your electricity through a fuel cell/electrolyser combo. This makes full off grid more achievable and (where it doesn't then become legally enforced to have a cinnection) breaks utility monopoly and puts a backstop on price gouging.

I'm not sure how long the window is between this becoming viable and batteries becoming cheaper than hydrogen storage is though.

or even a water heater

Is this more or less flammable than rooftop solar?

Could adjacent H2O and CO2 capture and storage help mitigate hydrogen fire risk?

I really cringe at the thought of H2 at home for multiple reasons.

- a wide explosive concentration range (LEL to UEL). The wider the range, the more opportunity you have for encountering an explosive mix if there's a leak.

- a low ignition energy. A small static discharge has more than enough energy to ignite H2.

- It's a functionally difficult gas to work with. It's an escape artist. You have to use the right materials. You have issues like embrittlement, hydrogen stress cracking. It's not great from a volumetric energy density perspective - more watts are required for pumping X units of energy than a fuel with a higher energy density. To bump up the energy density, you compress it and or liquefy it.. which costs energy, you've got high working pressures, and are possibly dealing with cryogenics as well.

FWIU actually Green hydrogen is where they're actually considered the total "path to value".

Charge the grid with it; whatever it is, if it's "economical": charge the grid with it.

> [ Hydrogen Safety: https://en.wikipedia.org/wiki/Hydrogen_safety ; videos: [ ]]

>> Contents: Prevention, Inerting and purging, Ignition source management (two rocks, HVAC, lighting, ), Mechanical integrity and reactive chemistry, Leaks and flame detection systems, Ventilation and flaring (all facilities that process Hydrogen must have anti-static ventilation systems), Inventory management and facility spacing, Cryogenics, Human factors, Incidents, *Hydrogen codes and standards*, Guidelines*

Would capturing CO2 and water with the same or adjacent PV/TPV+ panels help mitigate Hydrogen Hazard? FWIU, Aerogels and hydrogels can be made from CO2.

A possibility would be to put the H2 into a different storage medium like ammonia or methanol, rather than storing it as gaseous hydrogen.

"With a plan to decarbonize heating systems with hydrogen, Modern Electron raises $30M" (2022) https://techcrunch.com/2022/02/03/with-a-plan-to-decarbonize... :

> The second, which is still under development but about to make its debut, is what they’re calling the Modern Electron Reserve, which rather than burning natural gas — which is mostly CH4, or methane — reduces it to solid carbon (in the form of graphite) and hydrogen gas. The gas is passed on to the furnace to be burned, and converted to both heat and energy, while the graphite is collected for disposal or reuse.

And there's a picture of what's left after they extract just the Hydrogen from PNG/LNG for one day of home heat.

Letting the grass grow longer is one way to absorb carbon locally; longer grass is more efficient at absorbing carbon (e.g. carbon emitted by comparatively inefficiently burning natural gas for heat (an exothermic critical reaction))

Would be great if one could fill up a hydrogen fuel cell car with that.

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