But if you add solar powered lighting, remember that when there's a general power outage it's usual for the utilities to request that people flip a light switch on so that they can tell, by the presence or absence of light, whether your power has been restored. (And/or whether you're running your own generator that's gonna kill one of 'em when the pick up the downed lines.)

From an Oz point of view, that's an interesting point, John. Although I live in a rural situation where the grid is more linear than latticed, meaning power outages are not uncommon, I'm yet to experience any solicitous visits by electricity distributors. But your post raises other issues.

Here, all domestic installations connected to the grid must be inspected and passed before connection. Where a customer has a generator (240v, here) installed in such a way that both the grid and the generator are capable of powering the house (farm. shop etc), there must be an isolating switch installed in the meter box so that any self-generated power can't enter the grid. Does this not apply where you are in the US?

This "isolation" poses interesting contemplations for those of us who wish to use our sunny dispositions and photovoltaics to supply both our own house as well as contributing (attracting a rebate) to the grid. The ability to do this is being trialled in parts of Sydney but the supplier in my locality won't have a bar of it. [I regard Oz utilities as 'retarded' in this matter but they disregard such views.] Given that I live in an area where there will be bushfires I'm aware of a couple of problems where power generators capable of delivering to the grid are distributed rather than centralised.

Bushfires can cut power lines and can produce enough smoke to ionise the atmosphere; power outages are accidental in the first case and deliberate in the second. The last thing you'd want (and as a volunteer firefighter I am alive to the problem) is a lot of distributed generators putting power into a grid that you think has been isolated.

I reckon the easy and failsafe way of dealing with such situations is to have all consumers' meter boxes fitted with a relay that relies on a pulse sent from the grid's controller to keep the domestic wiring connected to the grid; if the pulse disappears (either because the grid supply/delivery has failed or has been shut down deliberately), the relay defaults to isolating the domestic wiring from the grid. In such a system it wouldn't matter to those working on the grid whether customers had generators or not and those customers who did have generators would still be able to have them operating without endangering powerline workers. Photovoltaic cells might only be able to supply minimal or no power if this happened but that's an issue for each customer.

Have you any thoughts on or experiences of such systems?

Cheers, Rowan