What I am concerned about is how you are planning to store that energy. Just for reference, 1kWh of energy is only going to push the spacecraft an extra 0.024 Ns. That is assuming perfect conversion to laser, the sail being perfectly reflecting, and all the beamed power hitting the sail head on. Storing the amount of energy required to do significant propulsion is difficult, your best options being chemical batteries and fuel cells.
From a sample energy density for Lithium ion batteries of 1.8 MJ/kg, you are going to need 40 kg of batteries per kg of spacecraft you want to accelerate by 1 m/s. (In practice, at least 100 kg including some energy losses).
Generating the energy on-the-fly may be easier, but there are still issues. If for example solar power is being used, you are still relying on the energy flux from the Sun like the solar sail, but are effectively losing 95% of the energy from converting it first to electricity, then back to light again. The laser station will in any case massively out weight the sail craft.