i don't know very much about it, but can you somehow take off the little solar panels off of the outdoor light things and make it so you can hook an outlet up to it and plug in to it like a phone charger for electricity.
Little solar panels on lights are very low power. The battery in one such may be 0.5 Amp-hours and .2 V ; it may be different but it should be marked on the panel/battery/manual. An outlet in your house is designed to run on 20 V (typically in N. Am.) and they run on alternating current (AC) whereas the panel generates direct current (DC). (If you don't know the difference, do not worry to much but just understand that they are not directly compatible.) You therefore need an inverter to change DC to AC (and lose some although inverters are now very efficient). But the amount of power generated by those panels is still very small. That is why solar lights are low power (just a few watts in most cases). To make things even more irritating, phone chargers do not work off 20 V AC as you are charging the battery and need a low voltage DC -- which is what the solar panel is giving you. It is almost certain that the voltage from the panel will be less than the voltage required for the phone. The charger is mostly cable but there is a black box incorporated and it should say what the voltage and current output are (the input will be 20V). So you should be able to overcome this not by hooking up the panel to a 20V outlet and then plugging the charger in but by hooking up the panel to the phone directly if you can get enough voltage out of the solar panel (or hook up several) and if you fashion a connection device. They already make them -- solar battery chargers and I am sure you can enter that into a search engine and find loads. Typically the panel alone is much more than a solar light -- which shows the relative power requirements.