I’ve helped my mate on a few solar installs and repairs. Work out what power you roughly use from appliances during the day and convert into kWh’s and multiply by going rate. Will give you an idea if there is any saving.
Each panel is roughly 250Watts, so rule of thumb, is that you get 1kW produced for every four panels depending on operating efficiency etc.
One job, lady had had a system put in when they were subsidised a few years back. All the sales paperwork was still there and they basically had promised the Earth. Think she’d paid about 9k for an 8 panel system and it was suggested that she’d save about 30k over the lifespan, making it seem very attractive, but obviously complete bullshit. My mate got the call because it had stopped working. Shoddy wiring on the roof and the inverter had packed in. Luckily for her, it was just in warranty and the manufacturer replaced it FOC. Still cost her price of scaffolding a d Labour to sort out the wiring on the roof panels.
Another one was when he got a call from someone who’s elderly parents had a system and then been conned a year or so later out of an additional 6k saying they needed to update it with some new optimisers to make it run even more efficiently. Long story short, he got their money back, but the system at best would save £120 a year, so for a couple in their 80’s, they were completely missold it in the first place.
Not be negative Danny, just be careful as they are often sold based on 100% theoretical output, but in the real world etc!
Ive got a 5 panel system sat waiting to go on my house but it didn’t cost me anything so it’s a no brainier.