prathmann

So the first thing to look at is how much power (Wattage) is used by that "bunch of lights" and for how long per day.

A typical commuting cyclist might be producing a total power output of around 100 Watts, so adding dynamos that consume more than about 50 W of his/her power is likely to add an unreasonable burden and turn the previously pleasant commute into drudgery. And the dynamos won't be 100% efficient at converting that 50W of mechanical energy into electricity, so 40W might be about all you could get (and most bottle dynamos will be much worse than that). So if your commute time is one hour/day then you'd have up to 40 W-hr to work with. But you'll use that to charge a battery which would then run the light(s) and there's a loss of efficiency in the charging/discharging cycle as well, so you might be down to 30 W-hr (i.e. 0.03 KW-hr) of available electrical energy from each day's one hour commute. Enough to run a single 30W bulb for one hour or a 100W bulb for 18 minutes.

Alternatively, you could pay the local utility company for that amount of power. Electricity is considered pretty expensive here in California, but the amount generated by a daily pedaling session of an hour under the above assumptions would only save about 15 cents each month.