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by ansgri 663 days ago
I'm not a pro in these systems (yet, I hope), but my understanding is that, beside lack of demand, HVDC is a safety nightmare compared to AC, and inverters are getting more efficient each year. So, even given the choice, I'd keep AC home-wide distribution and set up inverters in key places, with exactly the highest required voltage.
1 comments
kkfx 663 days ago
Well, yes DC is unsafe because if you get electrocuted instead of being "pushed out" you get "attached" to the conductors, but if you have a p.v. inverter at home you already have a 400V DC line from the module to the inverter, how different can be having the same to the garage? The same to an exterior heat-pump unit (where the DC compressor it's typically located) witch is also insulated by the mere fact you drive it via a remote?

Aside I'm not much an expert as well but, from DC to AC we are pretty efficient, around 98% of energy get converted. But the other way round it's pretty inefficient, meaning a loss around 30%. So while your p.v. it's pretty efficient in generating AC, your car it's pretty inefficient generating DC from AC to recharge. You heat pump would gain as well.

To be clear I do not advocate DC for any DC home appliance like washing machines or dishwashers, just for energy intensive appliances like big heat pumps and car chargers. Not more.

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ansgri 663 days ago
Valid points, though for safety I thought less about shock and more about fire: the DC arc is much more stable, thus the switches, breakers and relays have to be more robust. The rated DC voltage of magnetic relays is about 1/10 of AC.
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kkfx 663 days ago
Well... I'm ready to pay 10-time the price of an AC breaker to recharge regularly DC-to-DC and since that's the very same link than stationary 400V LFP batteries being able to use the car battery as a home one when I'm at home.

Try to imaging how well you could run if you have a small battery, as an expensive UPS for the home when you are not there (ventilation, homeservers, fridge(s)/freezer(s) etc) and when you are at home, thanks to a let's say 70kWh battery you can also run your heating in winter in case of a blackout...

In the end it's the very same power circuit, why not? 300€ extras in breakers to run my heat pumps more efficiently? No issue, they'll pay back countless more.

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