That's mostly the installation cost, thobut. It's expensive in the UK because labour is expensive and there are complicated bureaucratic hurdles to jump through before connecting to the grid, not because solar panels and inverters are expensive. It's even worse in USAnia (where, I note, they often have more sunshine and consequently use more electrons than we do) where it's basically impractical unless you're a business.
Sure, it's a marginal financial investment, depending on how much power you use (and even if you're a heavy user, you're probably better off buying shares in a fossil fuel company or something), but the advantages of clean, independent energy go beyond financial returns.
And sure, anything that costs money costs money. We were talking about EVs, which are a lot more expensive than £6k, and are currently impractical for most people who don't own a house with off-street parking. The question is at what point do you stop subsidising a technology that immediately benefits the well-off in order to stimulate the development of the technology. I'd say we're past that point, if only because other countries have done the job better than we have, and the technology is now mature. What we need is regulation to make the technology accessible to non-home-owners. Be that public charging, rules for landlords (eg. the Norwegians require landlords that provide a parking space allow an EV charger to be installed, as well as more obvious things like insulation standards), and so on.
