I tend to convert the time from the RTC chip into two variables such as timeH and timeM for hours and minutes

Code:
I2CRead SDApin,SCLpin,$D0,$00,[RTCSec,RTCMin,RTCHour,RTCWDay,RTCDay,RTCMonth,RTCYear,RTCCtrl]  ; read DS1307 chip

timeH=(RTCHour>>4)                                                  'convert the BCD format of the hours register and store in variable timeH
timeH=(timeH &$03)*10
timeH=timeH+(RTCHour&$0F)

timeM=(RTCMin>>4)
timeM=(timeM &$07)*10
timeM=timeM+(RTCMin&$0F)                                            'convert the BCD format of the mins register and store in variable timeM
And then its a simple matter to match values with other variables to turn lights on or off

Code:
lightsetHR = 14                         ' Set lights to come on at 2pm
lightsetMN = 00  

lightoffHR = 22                         ' Set lights to go off at 10pm
lightoffMN = 00
You could then used a simple logic routine like

Code:
If timeH >= lightsetHR and timeM>=lightsetMN then turn the lights on
If timeH < lightsetHR and timeM < lightsetMN or timeH>=lightoffHR and timeM>=lightoffMN then turn lights off

Or an alternative is to use a counter that resets at midnight. This only works where you need to turn the light on and off between 00:01 and 23:59 in the same day. This basically counts the minutes in a 24 hour period since midnight

Code:
I2CRead SDApin,SCLpin,$D0,$00,[RTCSec,RTCMin,RTCHour]   ' read the RTC
	
timeH=(RTCHour>>4)                        'convert the BCD format of the hours register and store in variable timeH
timeH=(timeH &$03)*10
timeH=timeH+(RTCHour&$0F)

timeM=(RTCMin>>4)                         'convert the BCD format of the mins register and store in variable timeM
timeM=(timeM &$07)*10
timeM=timeM+(RTCMin&$0F)                     

Counter1 = (TimeH *60)+ TimeM             'take hours and multiply it by 60 then add odd minutes to get the total minutes into counter1

Then use if/then statements to match the on / off times to the counter value to turn on / off the light

Code:
If Counter1 => OnTime and counter1 < OffTime then                     ' check to see if the time in minutes since midnight matches the on time
pin made high to turn light on                                                       ' insert the routine to make the pin high and turn the light on
endif                                                                           
If Counter1 => OffTime or Counter1 < Ontime then                      ' check to see if the time in minutes since midnight matches the channel off time
pin made low to turn lamp off                                                  ' insert the line to make the pin low and turn the light off
I've used both options in various projects and both work within the limitations described above.

Hope that helps