'Earlier this year, Utah became the first state in the country to pass legislation allowing people to purchase and install small, portable solar panels that plug into a standard wall socket.
"When attached outside to the balcony or patio of a dwelling, such panels can provide enough power for residents to run free of charge, home appliances such as fridges, dishwashers, washing machines and wi-fi without spending money on electricity from the grid."
The output of the micro inverter is a 110VAC plug so the current goes into your existing wiring feeding anything plugged in to other outlets on that breaker.
Theoretically, anything that can feed power back into the grid needs an interrupter to protect electric utility workers in the event their side is down. It appears these changes in state laws would allow PV systems producing low voltages to be hooked up to the house wiring. This is attractive for its simplicity and relatively low cost.
Anyone have any knowledge to share?
Most inverters will shut down if the grid drops... not sure about the mini inverters, though.
ReplyDeleteBalcony solar will work, except for units facing north, or on streets or in developments with a lot of trees. When I think of the apartments I have lived in, or the condo I owned, maybe a third of them would have supported "balcony solar" unless the city cut down all the trees on the street, or the apartment complex did the same, which would have made the apartments MUCH less desirable.
1: This new Utah law is an exemption from interconnection agreements for people generating 1.2 kilowatt of power or less.
ReplyDelete2: the micro grid-tie "plug-in" inverters used in the German balcony-solar are designed to shut themselves down should utility-power not be present. So no fear of creating a power 'island' to harm an unsuspecting utility worker.
The tech isn't at all new, but the need for an interconnection agreement is enough of a hurdle that doing micro grid-ties solar hasn't been worth the effort in most places for people prone to obeying the law and their electricity contract. (Analog meters spinning backwards is one often reported side-effect of illicit grid-ties -- and who wouldn't want to sell the power back at retail rather than the official grid-tie rate?
Of course the point of interconnection agreements is that utility planners need a handle on when, where, and how much power is being added to the system, as every additional watt of solar needs to be partly compensated with available dispatchable capacity (i.e.: beware the duck curve).
But as a side effect, the interconnect agreement requires local building and electrical-permit approval, which requires plan approval and inspection, so there are steps taken so that panels will be securely mounted to structures that can bear the wind and snow load.
Story: The previous owners of my house erected a shed to keep firewood dry, made from from steel tubing and poly panels. I was leaving for work one morning after an overnight storm and noticed that it was missing. I went for a walk and located it in the backyard of the house across the street, and inferred from tall tree locations blocking other paths too narrowly that it most likely arrived there by going over the roof of both my house and theirs. I was happy that it missed their above-ground pool (by inches!). It took me about an hour to dismantle, retrieve, and secure-down the debris. I think laypeople often underestimate how much force the wind can exert on a panel when the the direction of the airflow has made the panel into a sail.
I'd like to see some hard numbers but I already see issues with the story and concept:
ReplyDeleteFirst of all, as a sometimes rental unit owner, I do not allow modifications to the structure of the building, or additions that detract from the visual appeal of the building. My building, my rules.
Second, considering that a building has at least ONE side that is totally unsuited to solar (the north side), and two marginal sides, this is not a global solution. I have had solar arrays at rural properties, professionally designed, sited, monitored, and to produce sufficient power they are large - even with trackers.
And just plug into the wall? Sync with the grid issues?