Descartes"Insufficient power in capacitors?
what does that mean and how can I fix it please?
It means that the power draw for the system in question is too high for the power distribution system to keep up and you've exhausted the power capacitors.
Technical on power storage, unrelated directly to the answer requested
Capicators are a form of power storage that allow a quick discharge of power when a draw on the system is present. They fill in the gaps when the power generator cannot cope with a temporary draw spike on the system. Without going into too much more detail, power is nominal (normal) and also peak (absolute max). A generator is selected usually to meet nominal power, but not for peak power. When there is differential power available from a generator, i.e. the generator supplies more power than the system needs, you can install a capacitor to be charged by the generator. If the system reaches peak power demand, the capacitor is drained of power to keep the system on-line when the generator would not otherwise be able to perform the task alone.
Depending on the needs and task, you have a couple of options.
Cheapest-easiest:
adjust your power systems using your arrow keys. Left for systems (shields, sensors, etc.), right for hardpoints (weapons, mining tools, etc.), up for engines, and down for balance, IIRC is the default config for keyboard users.
You can see the current capacitor load and distribution in the HUD UI to the right of your shields. 3 power bars for the capacitor levels of power in each system, and the pips (0-4) represent the distribution of generator's power to refill the capacitors. 0 means no power goes to that capacitor- use it and you lose it. 4 send max generator power to that system. 2-2-2 is the balanced, but does not work well in several situations.
[Power Distributor Capacitors, full, set to max charge on engines and nominal charge on systems.]
If rebalancing does not work, you might need to upgrading/engineering your power distributor or your power plant, depending on how bad the power draw is.
Finally, IIRC, some things straight up drain your power, like thargoids. I don't do xeno, so I can't confirm directly.