[jacquesm]

There are some ways around that limitation. The reason it exists in the first place is so that the power company can safely power down their lines without installations such as yours feeding power back into the lines that are supposedly safe. This on the off chance that you'll end up electrocuting a line-man, which makes good sense.

Of course, since your puny little solar installation is incapable of powering a substantial portion of the grid this usually only really becomes a problem when the section that is islanded is small enough.

Some electrical codes allow you to resume powering your own circuit if you physically lock-out your connection during such an outage, and re-configure your inverter to non-grid connected mode.

You will also require a battery in such a case since the stabilizing properties of the grid (it's a very large load and acts as a huge flywheel or capacitor with basically endless capacity from the point of view of your installation).

And of course when the grid outage has been dealt with and you wish to feed power back into the grid again (or consume when the sun is down) you're going to have to undo all of this.

When I built a solar / wind power installation in Canada I decided that the net metering laws and price of power produced by renewables was so low that I scrapped the whole grid connectivity portion and invested the surplus into a much larger battery.

It felt pretty good to have power when the island was down which happened many times every year.

[tlrobinson]

"you're going to have to undo all of this"

Why can't "all of this" be packaged into one idiot-proof box with connections to the grid, your off-grid system, and your house?

[joezydeco]

You mean like a generator transfer switch?

http://www.generac.com/all-products/transfer-switches/home-b...

[jacquesm]

That's a device that you probably don't want to use with your solar installation since it will not handle the grid-present resynchronization at the end of a power outage correctly which could cause your renewable energy system to be re-connected to the grid at 180 degrees out of phase worst case when grid power is restored. The result will be a big bill for a large number of power FETs or IGBTs depending on the tech used in your inverter.

So you can't just add an automatic transfer switch to retro-fit this to an existing inverter, but there are plenty of inverters where an option for an external module can be purchased or where an automatic transfer switch is built into the inverter itself:

http://ww3.wholesalesolar.com/newsletter/MAGNUM-AC-COUPLED-L...

These inverters will first synchronize with the grid before they connect.

[jacquesm]

Depending on local variations in electrical code it can be. But check with a licensed installer familiar with your local code.

[davegardner]

Yes it's not such a problem when it's just my 5 KW system. However here in Perth, Western Australia there are a lot of sunny days, so domestic rooftop solar systems are very commonplace now.

In my case there's some significant financial incentives to stay connected to the grid (I actually get a cheque from my power company for most of the year). That'll change in another 6 years time when this higher buyback rate expires, so I'll be looking very closely at whether I want to remain grid connected at that point.

[maxerickson]

That's allowed in Connecticut:

http://cga.ct.gov/2011/rpt/2011-R-0390.htm

$300,000 liability policy requirement right at the end there.

There's also similar rules for installed generators, it's not clear to me how they would treat a big battery.