Question: I have a floating solar pump with panels putting out 30 volts and 360 watts. The meter shows 30 volts at the pump end but as soon as I connect the 24 volt pump it drops to 3 volts and obviously doesn’t work. It’s not the pump as I have tested it on batteries and it works fine. Can anyone tell me what’s happening, maybe the panels or submerged cable is stuffed I don’t know

Answer: 
You didn't mention your load but try to measure the current flow. If there is no voltage drop anywhere in your system, it's because of your load.

In theory,

1. ```
W = I * V

```
2. ```
360 = I * 30 => I = 12A (Max at fully charged state)

```
3. ```
360 = I * 24 => Iload = 15A

```
4. ```
360 = I * 3 => Iload = 120A 

```

*(Thats too much current, there may be short somewhere but still depends on your system and I don't know it)*

*These are presenting the fully charged state.*

But in most common cases, it's not working like that.

For example:

*Your solar battery has charged 120W/s and your load is constant 5A,30V which means 150W/s. It will start to run at these parameters but the voltage will decay eventually.*

Probably your load has higher power usage and dissipation than your solar system so it's not enough to run the system all the time.

*This should be a comment but I don't have enough reputation to comment.*
Assuming that the solar panels were designed as a package with the pump, the panels should be operating at about 24V when connected to the pump. The collapse of the loaded voltage indicates (normally) that the panel, or part of the panel, is shaded, and can't supply the current required.

Abnormally, collapse of the voltage indicates that part of the panel is just not working: broken, corroded, disconnected, having the same effect as if it was shaded: not supplying the current required.