Capacitor to charge then power Leds

Yes but I think you will need to tell the readers what size capacitors and chager you have.

To be honest the energy stored in Capacitors isn't that great you would need a true monster to drive an LED for say an over night light.

If it was that easy the cheapo solar cell Lights for the garden would get rid of the batteries as they are a pain to charge propperly

By connecting an electrolytic capacitor across the D.C supply across the supply used for powering the LEDs, would it give flickering light or stabilised light

or by choosig appropriate values of capacitor, can we get the above features independently?

The solar cells put out 15VDC which is well within the capacitors voltage rating so you would get a steady light. The number of capacitors in parallel would increase the length of time the LEDs stay on. As the capacitors discharge the LEds will become dimmer until there is no longer enough voltage in the capacitors to bias the LED on at which time it will turn off. If you want constant brightness then use a current regulator in series with the LED such as the NSI4502A http://www.newark.com/on-semiconductor/nsi45020at1g/ic-ccr-led-driver-linear-sod-123/dp/15R4677?in_merch=Popular%20Drivers%20And%20Interfaces.  The datasheet has several application notes that will help you understand how to hook up LEDs in different formations for an optimum design.

The other posters are correct, in that once charged, the capacitors will give an output, while the solar panel has no output.

Be aware that as capacitors age, their capacity drops, so unless you actually measure them assume they have lost 20-25% capacity.

With a solar panel of that size, you may wish to charge a Gell Cell (with a charge regulator) which will give you plenty of light/time.

If you assume you have 18w at 80% for 8 hours = 115.2 watt hours of charge on a good day.

This means you can safely run a load of 4.8 watts for 24 hours, or 9.6 watts for 12 hours.

Thats a fairly mean LED light.

Mark

The other posters are correct, in that once charged, the capacitors will give an output, while the solar panel has no output.

Be aware that as capacitors age, their capacity drops, so unless you actually measure them assume they have lost 20-25% capacity.

With a solar panel of that size, you may wish to charge a Gell Cell (with a charge regulator) which will give you plenty of light/time.

If you assume you have 18w at 80% for 8 hours = 115.2 watt hours of charge on a good day.

This means you can safely run a load of 4.8 watts for 24 hours, or 9.6 watts for 12 hours.

Thats a fairly mean LED light.

Mark