Home made batteries are expensive, easy to fail, easy to spoil, potentially harmful to the environment and you need really a lot of them to get out meaningful amount of electricity.
Your question is pretty vague, it is not clear what you mean by "usable electricity".
If you need light, it is easier (cheaper, reliable) to use candles or oil lamps.
If you need electricity to drive electric devices, than you most probably need a predetermined voltage, which will be difficult to reliably produce.
If you need a substantial amount of electricity to drive light and several electric devices, it is very hard to do it with any kind of battery-like equipment: just think it over how many batteries you need the produce a kW electricity.
- Batteries per definition contains corrosive in one way or another, and DIY level technology risks that corrosion occurs much less predictable way. You have to figure out how long a battery can be stored reliably before you get everything soaked in rotten citrus juices.
- Since you most probably use metals in this battery, it is a good question how poisonous your new and used battery will be and if you can trash it without major environmental damage. It is not nice to spill out large amount of dissolved copper or lead in the garden.
- If you do any kind of electricity work, and you are not good at it, especially with potentially corroded equipment, you may have a lot of problem with contact errors and other reliability issues.