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Comment by citrin_ru | Hacker News Reader

There are some safety concerns at least for relatively powerful panels - e. g. if a circuit breaker is 30A you can draw up to 30A from the grid in absence of panels. If you connect a panel which can provide another 30A then a device in theory will be able to draw 60A from the socket not triggering circuit breaker which will overload the socket circuit.

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Since the panels don't plug in directly but have to go through an inverter that turns the panel's DC into the grid's AC, you can "solve" this by limiting the maximum output current of the inverter to some safe level (e.g. allowing 8A of solar on a 20A circuit, eating into safety margins). You can still connect powerful panels, but all that will get you is more output in mornings, evenings and under cloud cover, not more max output.

Or you can pair it with a reasonably sized battery to store midday "surplus" (any generation beyond the determined safe level) and release it into the circuit when the panel generates less

They don't generate anywhere close to 30A for exactly that reason. They are limited to 400W (4 Amps)

https://duckduckgo.com/?t=ffab&q=balcony+solar+maximum+watta...

Most circuits with standard plugs on them are 15A in the US. A single space heater will fully utilize one.

It is also why every space heater in the United States uses exactly 1.5KW. It is like maximum strength medication. You can't legally buy more, and no one wants less.

Does it make sense to sell panels that plug only directly into the fusebox ? To avoid overloading in-wall wiring.

That's how traditional (not plug in) panels are connected. The problem is - you need to route a cable from window/balcony to the panel (which may be located outside an apartment in a hall) and if you want to hide the cable in walls it becomes expensive. With plugin you can use closest to the panel socket. En easier solution is a clamp power meter on a socket circuit connected to the inventor via z-ware / zigbee so the inverter can see total socket circuit load and limit own power as a protective measure (at which point a circuit breaker likely will be tripped).

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