There are no free solar panels, despite ads that you might see claiming such.
What you can potentially get is $0 down financing of solar panels for your home. Much like any financing – car loan, home loan, credit cards, etc – it’s certainly not free. You are deferring your costs and spreading them out over time, and you are paying someone (typically the financing company) extra for the luxury of doing so.
This still could be a good deal for you, but it is not free.
In the US, getting solar for your home will cost you on the order of $3 per Watt (in 2019). In other parts of the world, it is significantly cheaper – below $2 per Watt.
A typical home solar system in the US is 6,000 Watts – so you are looking at $18,000, before any tax credits or local rebates you might be eligible for. That same system might be less than $10,000 in Australia or Europe.
If someone is saying you can do it for much less than that, read the fine print. You are likely getting misled in some way or another.