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Solar won't keep you online through a power outage. The inverter is required by law to cut power from solar panels when there is not power from the grid, so as
by cheald 4y ago
Solar won't keep you online through a power outage. The inverter is required by law to cut power from solar panels when there is not power from the grid, so as to avoid feeding electricity back into the grid lines (which technicians may be working on!) - this is known as anti-islanding protection. If you want to be online through a grid outage you need a battery array.
- CTmystery 4y agoFrom a circuit perspective, it seems trivial to open a switch back to the grid to prevent grid-feed, while still feeding the internal circuit that is the house. Can you help me understand why this is hard?
- cheald 4y agoIt's doable, but it requires a bunch of extra expensive equipment. Most people that want to accomplish that goal just install a battery array instead, since you're spending the money and it also gets you power coverage when the sun isn't shining. But the point stands that the typical grid-tied solar system just turns off when the grid goes down.
- aiProgMach 4y agoIt's not hard. There is type of inverters that called "Hybrid inverter", I have one that can keep power off-grid or on-grid or even on-grid in import mode only (so only import any needed power without exporting...), and it can work off-grid even without battery (from solar) but that is not recommended unless you know that your load is much smaller than the solar output, even small lead-acid battery can mitigate this issue. The way the inverter work is that when the grid goes off it will automatically switch the power export off and keep the load running from solar and/or battery in isolated mode.
- zombielinux 4y agoThe problem is that its not a DC connection to the grid. Not only do you have to match voltage on re-connection, but you have to match frequency AND phase. Its "doable" but to do so reliably without a stable reference can be challenging. That's why the DC requirement is there. They want some form of reliable power to well tested electronics to match phase and frequency when the grid comes back up. A heavily loaded AC line will drift in voltage and frequency stability (say when your AC kicks on and browns out your solar panels).
- grecy 4y agoI've read that before, and I have a further question if you could indulge me What if, when the grid goes out the inverter keeps powering the house (and disconnects from the grid). Then when the grid comes back on, kill the output of inverter (which results in outage to the house), reconnect to grid, then power up the inverter again, which skirts all the sync issues. The house will see a few second outage... but it will have been "on" for the entire grid outage, which I think is much preferable.
- maxerickson 4y agoThe overall problem is more or less solved, it just adds equipment to the installation, both to make the power usable and also to ensure that it is isolated from the grid.
- deleted 4y ago[deleted]
- Xt-6 4y agoIt is possible to do this without battery, but you need some special inverters, like the Enphase IQ8.
- dymk 4y agoNot just that, but an ATS needs to be installed like the Enphase Enpower. That's usually at least a few thousand to have an electrician install.