Not sure what you are after, large solar is simple, small solar a bit of a trade off, the problem is a controller uses energy, so with a large panel no question a switch mode type controller well worth while, but with smaller units not so cut and dried.
In the main we need some thing to store the energy, like a battery, these have a fixed voltage, but the solar panel will produce more power at a lower voltage morning and evening than at mid day, so to get the maximum power we turn the DC to AC and transform it to what the battery needs and then turn it back to DC.
But for a small unit this uses more power than it gains, the same for turning the panels to follow the sun. So size is important.
Also selection of battery, alkaline batteries can be left part discharged for ages, in fact they are better being discharged to being fully charged, acid batteries are the reverse, they become damaged if left discharged.
You will find that a large number of contributors here have an irrational hated of solar power. I suggest visiting a site where living off-grid is considered a good thing. I don't believe I'm allowed to post a link here, but maybe search for camelot-forum.
Do they? I certainly don't. At the very least, having at least some local solar generation will decrease the demands on the grid (and thereby result in environmental benefits etc.).
However, many/most people seem to consider it not in those senses but, rather, as a means of 'cost saving' and I think that they need to examine very carefully (and objectively, based on good facts and sensible assumptions) the financial effects of having a UK domestic PV installation, in the short-, medium- and long-term, and taking into account their personal circumstances, before concluding that it may be a (financially) sensible option for them.
As with other 'investments' which are ill-advised for some, I do suspect and fear that many end up having PV installations (often because of marketing blurb and/or unrealistic assumptions and/or failure to think through the financial implications over time) when it probably is not very sensible for them, in their particular circumstances.
Kind Regards, John
Edit: Ah, hadn't seen JohnD's post - but we seem to be saying much the same.
Like the others, I disagree with that.
Many of us have (lets keep it polite) "considerable scepticism" about some of the policy and rhetoric around renewables, not to mention an understanding of just how much it's costing to adapt the grid to accept these widely fluctuating energy sources.