I’m interested in solar. And I know I need a inverter to convert the DC power form panels/battery into AC so my appliances can use them. But I’ve heard this grid forming inverter in the news. How is it different to ones installed in homes? Do I even want one or is it only for power plants?
In: Engineering
When you connect a generator to an AC grid, you have to synchronize and match the phase of the two power sources.
The kind of inverter you’d use while camping can’t do this at all. The ones you’d use for net metering will listen to the grid to see what the timing is, and connect appropriately, but require the grid to be up and running before it will start sending power to the grid, and will disconnect from the grid when the power goes out.
Grid forming inverters would be capable of jumpstarting a grid that isn’t currently running. You’d need to be able to synchronize them without the benefit of the power already being on. It’s not something to worry about if you aren’t running a power grid.
Normal home inverters tend to be “grid tie” inverters. These are designed to be connected to a working power grid and feed in.
The problem with this is that if there is a power grid failure, like a broken power line, then home inverters can keep the damaged line energised. So, if a linesman goes out to fix a damaged power line, they’ve switched it off at their end, but if there is an inverter back feeding, they could still get electrocuted.
Grid tie inverters monitor the grid health continuously. If they detect a grid anomaly, then they automatically shut down and lock out. They will not reset and reboot until the grid has been reconnected and is healthy.
One of the things that grid tie inverters try to check for is if multiple grid tie inverters are connected together in a disconnected grid. They use a variety of techniques to detect this and shut down to make sure that they can’t accidentally “form” their own power grid.
A grid forming inverter is an inverter that is specifically designed so that it can start up on its own without a healthy power grid and if multiple are connected together they will play along and share the power demand.
Grid forming inverters must never be connected to a public power grid withiut specific permission from the grid operator because of the risk that they start powering up a damaged grid and the grid operator can’t control the inverters.
Grid forming inverters are used by power plants such as solar farms and wind turbines. Grid forming inverters can keep going if the grid is having problems and try to keep the power on. Grid tie inverters shut down at the first signs of trouble.
As long as the grid operator can monitor and control and knows about the grid form inverters they can work safely. Grid tie inverters are normally used in individual homes and don’t have full remote control, etc.
Solar setups can vary greatly, generally if you are building one to power your house, you would need licensed electricians and i believe a permit in a large number of places, this is because a home solar setup can backfeed excess power production to the grid and pay you for it and it takes some management to load balance and match your phases and timing to be compatible and not destructive.
A solar setup for a camper or RV would just freehand the phases and it doesnt matter so long as it doesnt get capacitively coupled or inducted into another power grid while at AC currents. These systems can be really cheap and also of a low build quality but are generally fine if you factor in how it will be used properly. For certain things like sensitive electronics you may want to beef up on your inverter tech and find a pure sine wave inverter, which can draw a bit more power and perhaps waste under 5%, but it will run things that do not like modified sine waves, which are square voltage pulses that attempt to emulate a sine wave but on a timescale are not gradual but instant DC-like pulses in a stairstep shape.
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