It's impossible to give an exact number of solar panels in the world. There's no central database tracking every single panel installed. However, we can estimate based on installed capacity and the average panel size.

Here's what we know:

* Global solar PV capacity is estimated to be around 900 Gigawatts (GW) as of 2023.

* Average solar panel size varies, but a common size is around 300 watts.

To estimate the number of solar panels:

1. Convert GW to Watts: 900 GW = 900,000,000 kW = 900,000,000,000 W

2. Divide total wattage by average panel wattage: 900,000,000,000 W / 300 W/panel = 3,000,000,000 panels

This gives us a rough estimate of 3 billion solar panels worldwide.

Important notes:

* This is a very rough estimate. Actual numbers could be higher or lower depending on factors like:

* Variations in panel sizes

* Changes in installed capacity

* The inclusion of other solar technologies like concentrated solar power

* This number only represents panels installed for electricity generation. It doesn't include panels used for other purposes like water heating or lighting.

Therefore, while we can't get a precise number, it's safe to say there are billions of solar panels installed globally.