Energy Matters Forums

[maland]

I have recently installed solar panels and are disappointed to learn that they only operate while there i sa apower supply why is thsi so I had thought during really hot weather the solar panels would get me through a power outage

[JuliusH]

The power is taken of to protect people that have to work on the electricity cables. If your system would continue to generate electricity and this would be feeded in the grid, the workmen could be electrocuted.

The only option would be to go off-grid, but that is usually to expensive unfortunately.

[SR76]

Yep. It's a safety thing, and maybe the only real weakness of a grid-connect system in urban areas.

There are now some systems available which allow grid-connect + fully integrated battery back-up (i.e. seamless transfer to back-up power if the grid goes down). "Sunny Backup" by SMA is one that's come out recently and looks pretty slick.

I have a small battery / micro-inverter system that I use as my poor-man's backup - two panels charge a battery which I use for small loads, completely separate to my much bigger grid-connect system. Haven't used it in an emergency but I'm enthusiastic.

Cheers,

-SR

[SR76]

(Oh, yeah, you could do a similar thing with a battery charger if you don't want to run separate solar panels...)

[wandifred]

Hi Guys,

The installer of my system suggested that if you could get a good generator connected to the house with an isolator switch to keep the electricity off the grid, the PV inverter would sense the electricity and kick in. This way your panels would suppliment your generator.

I'm not sure if this is doable I'm not an electrician. Perhaps some knowlegable member might be able to add light on this.

Cheers,
Fred

[bpratt]

Hi Guys,

The installer of my system suggested that if you could get a good generator connected to the house with an isolator switch to keep the electricity off the grid, the PV inverter would sense the electricity and kick in. This way your panels would suppliment your generator.

I'm not sure if this is doable I'm not an electrician. Perhaps some knowlegable member might be able to add light on this.

I'm not an electricion, but I'm guessing it is possible, particulary if you wan to spend the money.

If you have a "good generator", then chances are you've got a one big enough to power the whole house, and more than likely produces more power than your PV system does. i.e. I have a 8kw diesel generator here, and whilst I still don't have a PV system yet, I'll be starting off with a 3kw with a 5kw inverter to put more panels on later.

So for me the short answer is don't bother, but for someone else with a 3kw PV system and a 1kw generator then it might be subject to cost, justifiable.

[taggertycyclist]

The issue of powering up a generator and connecting it into a home electrical system during a mains outage was discussed by a caller on an ABC evening program recently in Melbourne (the caller was from my locale).

There was a rapid response from electrical experts exhorting people NOT to even remotely think of doing this UNLESS they had spent around $300 to have a qualified electrcian install a special power socket that totally isolates the house system from the mains when the generator gets going.

Feeding power back into the mains system even from a small generator apparently is enough to get the step-up transformers going so the linesmen working to repair the fault face the very real and fatal possibility of being electrocuted by 100,00 volts from that tiny little 1kW gennie.

[bpratt]

There was a rapid response from electrical experts exhorting people NOT to even remotely think of doing this UNLESS they had spent around $300 to have a qualified electrcian install a special power socket that totally isolates the house system from the mains when the generator gets going.

That's basically what we've got here.

The generator is completely isolated from the mains when in operation.

We're going to leave everything the way it is when we go solar, so there won't be an issue with power going back up the mains.

[wandifred]

I have a 5.5 kVa generator that I would like to have profesionally connected to my house eventually to use in case of a major power outage. The generator is a bit small to run all I have in the house but with my PV panels kicking in, it should be sufficient through the day. I would hope that on a warm sunny day, the generator would only be just ticking over and so not be using much fuel and should be able to run for much of the day without a refuel.

Cheers,
Fred

[Gr11zzly]

The power is taken of to protect people that have to work on the electricity cables. If your system would continue to generate electricity and this would be feeded in the grid, the workmen could be electrocuted.

The only option would be to go off-grid, but that is usually to expensive unfortunately.

I understand the need to protect the grid during an outage. A change over switch should do that.
I was thinking that it might be possible to stimulate the solar panel inverter into producing power by using a small sinewave inverter operating from some back up batteries.??
Does anyone have any experience of this? How much power would be needed to stimulate the solar inverter? Surely this is not that different from operating two inverters in parallel.