Solar - real-life experience of investment vs return

roadweary

Hi,

I've been interested in solar panels / batteries for a while.  My research to date has been limited to personal posts on Facebook where only a couple of very vocal (and mainly anti solar panel) people contributed.

The situation is that both my wife and I work from home.  House was built around 1998.  It's a brick built, end terrace, town house (3 floors) 3 bedrooms.  The loft is insulated. 

We have a gas combi boiler an induction hob and an electric double oven....and all sort of electric cooking devices.  My wife has a new ~4.5 x 5 metre garden office with underfloor heating and a small aircon (hot and cold) unit.  

Now it's totally non-scientific, but when it was icy outside and my wife was working in her office, we were getting through £15-£17 of gas/electric per day.  Assuming the smart meter is accurate.  It's now not so cold, but also my wife hasn't been working this week and the smart meter is showing more like £10-11 per day.

So allowing for maybe 250 working days, that's about £1,250 difference a year.  Now of course seasonal things will make a difference to how much heating or cooling is used....and there's no guarantee that we'd be able to generate or store all the electricity that we need.  But that was the starting point to me thinking about investing in solar again.

It also seems that electricity is only going to get more expensive.  In the short to medium term, there is the pricecap support being reduced / removed....and in general everything gets more expensive....although we could hope that utility prices are a nasty 2-3 year blip, I'm not convinced.

Anyhow, that finally takes me to my point.  Has anyone here installed a solar solution (price / type?) that could comment on their real-world experience of savings...or otherwise?

My concern is that it's going to be a reasonably big outlay (I suspect we'd need at least a 5-6KW solution), I don't know the ongoing costs of maintenance (my step son says that people don't clean them and so they become less efficient - and getting to our roof is pretty difficult due to the 3 stories and surrounding terrain) etc.  Oh my step son also commented on cleaning solar panels where lichen had grown and destroyed the surface where is had been and the coating of the panels peeled around that area.

Also, along with electric cars, we are always hearing about the next big thing in batteries and also solar panels being around the corner (I read an article about super thin and light panels being worked on) and there is that added concern of getting technology that suddenly becomes outdated.

I'm kind of surprised there isn't some government sanctioned organisation that could do surveys, look at your house, electricity usage, and all the other various factors and be able to produce a report suggesting the most appropriate option(s) to consider; even if that were as a paid service.  Surely if the government were serious about reducing our reliance on the grid, they'd do something along those lines.

Anyhow, I've spewed a lot of words - apologies, but if you've made it this far, I'd love to hear your thoughts.

Another thing I've considered is seeing if there are any good FB forums where similar things are discussed.

Thanks!

ABrass

Given current prices as long as you're paying less than £1,500 per kW of panels (eg. a 4kW array for less than £6000) you'll save money over 10 years and a lot more than that over the 25 year lifespan.

A rule of thumb is that you would benefit by having enough generation capacity to provide your yearly power demand. So if you expect to use 4,000kWh then getting enough panels to provide 4000kWh over a year is a good fit

What's your annual electricity consumption? It should say on your electricity bills (estimated is fine, yearly summary is better).

Batteries are nice but they are borderline on value for money. I went for one but there are strong arguments for waiting a few more years before getting one.

Solarchaser

You don't state your location, if you are in Scotland there are 2 things to say.
1. You will be able to collect less solar than someone in southern England. 
2. There is a public service from the government called the energy saving Trust which will do a free survey with recommendations on what would work for you.

In 95% of cases, solar will have a positive roi as long as you don't get ripped off on installation. 

I dont think batteries will be a good solution as you work from home so are able to self consume a good amount.

roadweary

Hi, 

Thanks - in Gloucestershire. 

I have no idea where to start in terms of manufactures or installers. 

I think batteries are a major part of the cost…but I also wasn’t sure if the power generated would be steady enough through the day so thought some kind of reservoir might make sense?

I do need to get an idea of how long the investment would take to pay for itself. 

roadweary

ABrass said:

Given current prices as long as you're paying less than £1,500 per kW of panels (eg. a 4kW array for less than £6000) you'll save money over 10 years and a lot more than that over the 25 year lifespan.

A rule of thumb is that you would benefit by having enough generation capacity to provide your yearly power demand. So if you expect to use 4,000kWh then getting enough panels to provide 4000kWh over a year is a good fit

What's your annual electricity consumption? It should say on your electricity bills (estimated is fine, yearly summary is better).

Batteries are nice but they are borderline on value for money. I went for one but there are strong arguments for waiting a few more years before getting one.

Thanks - I’ll find out and report back. I guess there’s what a panel can produce vs the actual sunshine received…

ABrass

Solar power is very intermittent and often generate when you don't need it. Without a battery you would be doing well to use 1/3 of what you generate. The rest is exported to the grid and you get some money for it.

Batteries allow you to charge up and save the power until you need it. With a battery you can use more like 1/2 or maybe even 2/3 of your power.

Since you get paid less for export than you pay for import this obviously saves money. But batteries are very expensive. It will take a long time to pay off that cost. Normally it's better value to spend more money on more panels rather than getting batteries.

Alnat1

What's your annual use? How big is your roof? Which direction does it face? Any shading?

Solar works from Mar-Sep but you'll probably be buying some electricity from Oct-Feb, it's unlikely to produce enough to heat that office over the worst months of winter (there'll be quite a few dark, damp days when you produce less than 1kWh) but it's possible, with a battery and the right tariff, to fill up on cheaper overnight electricity to use during the day.

roadweary

So, year to date is 6057 kWh.  The roof is south-ish facing with no shade any time of day.  Roof size not so sure, but I'm going to guess at about 5 metres width.....and looking at an aerial photo from Google maps, maybe 6 metres to the apex, so perhaps 30m2 on the half of the roof that would be used.

I think Google Maps shows the top as North, so the house with the dot is ours....perhaps South south east?

Officer_Dibble

I'd recommend getting in touch with Light Renewables in Maidstone. As far as I know they travel a fair distance. They quote after a fairly quick phone call and assess the roof from Google Maps (but do a slightly more thorough survey before installation). It'll give you a good base price with and without a battery and with no negotiation on price, so at least you know what you're aiming for if you decide to use a more local installer. Everyone's very busy and equipment's still a bit scarce, so prices and lead times are both high.

There are various sites to calculate potential return - this one's quite neat and can work out return with and without battery:

https://great-home.co.uk/solar-export-guarantee-seg-calculator/

For the calculations your export price setting can be 15p a unit if you're willing to switch to Octopus. Who knows where the electricity price is going long term, but using the current post-EPG price of 35p a unit might be a good starting point. Try putting installation costs of £7000 for a 5kWp system and £6000 for 2x6.5kWh batteries and see what it comes up with. Annual generation roughly 5,000kWh from a 5kWp south-ish facing system. Your high usage in winter compared with summer might throw the calculators somewhat and is what might justify decent battery capacity for night time charging - my 6.5kWh battery wouldn't last you long from November to March.

roadweary

On a slight tangent, as we are a 3 storey building.....with stairs and very bad access all around for installation / cleaning....how do flat roofs stand for solar installs?  Here is the new office....perhaps a jot over 16m2.  Again, it is never overshadowed.  It is at the 2.5m max height avoiding planning permission issues.

Not sure if solar panels have to go at a certain angle, and if so, whether the additional height would be considered part of the structure for planning purposes?

Reed_Richards

I have 4.8 kWp of panels and a 6.5 kWh battery.  My inverter say in 2022 I imported 5470 kWh of electricity, my meter says 5655 kWh, so not too far out.  According to the records made by my inverter I exported 1089 kWh and used 2716.42 kWh.  The battery helps a lot in boosting my self-consumption.