Photovoltaic [pv] panels to generate electricity have been in the UK news recently;- http://www.currys.co.uk/solarpower/index.html
[Currys is a large UK electrical retailer.]

The system they are selling is by 'Sharp'.
Summarised, from their website;

Roof mounted panels: Currys quote a value of 1600kWh/annum produced from a 'typical' system having a rating of '2kWp' (whatever that means. They say it means 1kWp = 800kWh/year! 2x1 = 2 [Linked Image] ). The pv units carry a 25 year warranty. The panel[s] supply dc output to-

An externally placed inverter. This creates ac of poco 'quality' and sync, which feeds to-

A 'production' meter, feeding power direct to the National Grid. Customers will be paid/credited for this power. [ Not all of the present UK pocos, some of whom are actually just 'brokers', will do this; a customer may need to change to a company that will. ]

The poco supplies electricity to the customer from the Grid via a second 'consumption' meter.

Note; There are no batteries, the customer is still Grid connected, and all the power actually consumed in the home comes from the Grid.

Technically, this is quite a neat scheme. It retains the security of being Grid connected and it retains the home's existing panels/fuses/breakers and other safety features etc.. There is no battery system, which reduces complexity, maintenance, storage and first cost. As long as the Grid is up, you have power. You have power at night, and your pv generation to the Grid is paid for. At what price per kwh is not revealed, of course.

Furthermore, Linesmen safety is assured because the system shuts off automatically in the event of a power outage; it won't backfeed the local transmission lines.

Quote: " There is no product that can be added to [the] pv system to act as a back up at the present time".

The present cost is 'from' £9000 for a 'complete package' generating about 1600kWh per annum, and consisting of 9 arrays and all the necessary kit, fitting, wiring etc..
Currys are naturally reticent about payback, and waffle a bit about 'increased house-values', a much cherished UK phenomenon; but I reckon straight payback, based on power generated, at about 66 years at present UK power prices.

Solar power arriving on Earth as light, [ ie photons, the 'fuel' of these devices], is quoted at about 1 kw/ square metre, [1 kw/ 10 sq. foot] in mid-lattitudes. Efficiency of conversion is about 10-15%. One US website quotes an output of c 10.75W/sq. foot, or 1kw per 93 sq foot ( ie. a square of 9ft 6" sides ) of panels. This would vary during the day /time of year/ lattitude, of course. Prices per square ft. vary enormously, as you would expect, but a price of US$6000 per kw output [US$65 a square foot] has been seen quoted on the net.

All I can say is, they are not going to get killed in the rush on those figures. The cost has to come down, perhaps through grant aid / tax breaks?

Alan

Wood work but can't!