Difference between the terms voltage generation and power generation

What exactly is the difference between 'generating a voltage' 'generating a current' and 'generating power'? Are all these terms linked in some way? And for which situations do I use each term?

For example, do we say a solar panel generates power or voltage when radiated by sunlight?

Three scenarios spring to mind: -

• Voltage is generated by "a process" and the connected load takes a current as per ohms law. That current and that voltage implies a power as in volts x amps. This is the normally referred to as power generation but power is only generated if a load is connected.

• There are other "processes" that generate a current (as in a photo-diode detector) but these tend to be used into short circuits (as per a trans-resistance amplifier) so there's not really a voltage or power involved.

• Some "processes" directly generate "power" as in the far field of a transmitting antenna or the light emitted from a lamp or LED.

do we say a solar panel generates power or voltage when radiated by sunlight?

It cannot generate power without a load but it can generate a voltage and that can produce current into the connected load.

• Oh okay. So if I were to just leave a solar panel in the sun, does it collect all that sunlight and store energy in the form of voltage inside it? Essentially asking if the solar panel becomes a battery. Jul 19 '20 at 14:10
• No, it doesn't store energy. Jul 19 '20 at 14:16
• Oh okay. So how does a solar panel (kept in the sun) behave when it is not connected to any load? Does it just sit there getting hotter due to all the photonic energy? Jul 19 '20 at 17:34
• Yes it does just that. Jul 19 '20 at 17:58

All three terms are likely to be used interchangeably when talking casually.

However, if we want to be precise, then there is a very clear difference between them.

We can theoretically generate a voltage, or a current, using no power, or in practice very little power to cover the losses. It's quite easy to generate a high voltage, and as long as no current has to flow, it doesn't need much power. We could maybe generate 1 kV, or 1 MV, using the same small amount of power. You can get a large current flowing at very low voltage, some motherboards generate over 100 A for the CPU at very low voltages, without using much power, while superconductors can circulate a current indefinitely.

To generate power however, requires power. If you want to generate 1 kW of electrical power, whether that's 10 V at 100 A, or 100 V at 10 A, then you need at least 1 kW of some other form of power to do it. It might be mechanical power from a engine or water turbine, it might be solar power incident on a solar panel.