cheaper times to use:

http://www.energycustomers.ie/faqs/index.aspx

Some good info above

Night time electricity prices will increase faster than day time prices. The consumption and generation patterns of the past are changing fast.
In the Netherlands for example the night time tarif is already higher than the day time tarif:

http://www.volkskrant.nl/vk/nl/2664/Nieuws/article/detail/3131928/2012/01/21/Met-nachtstroom-ben-je-duurder-uit.dhtml

Base load power plants are closed down due to cheaper,more competitive renewables, stand-by power plants are expensive since ongoing costs have to be covered with lesser produced/sold electricity: the generation price per kWh rises.
No sunshine AND no wind means standby power plants have be used for electricity generation. Esp.at night time.

A typical scenario of this is seen now happening at the moment in Scotland, with more wind energy in the grid the base load becomes to expensive to be sold. So the base load power plants become redundant and are either scrapped or changed to stand-by powerplants:

http://www.pennenergy.com/index/power/display/3043662251/articles/pennenergy/power/gas/2012/january/sse-to_suspend_over.html

in combination with

http://www.pennenergy.com/index/power/display/3043662251/articles/pennenergy/power/gas/2012/january/sse-to_suspend_over.html

Most German utility providers have no night saver rates anymore, Switzerland and Austria are following.

So be warned when betting on cheap night saver rates for heat pumps etc., these are a thing of the past.

The intelligent meter will prove the duds to be stupid - so to say.