Solar Panels

[Marchrider]

I am thinking of getting some on the house - any thoughts on do's and don'ts, what's good, whats bad

 

[Alex321]

Definitely do if you have the capital.

Slightly more questionable if you need a loan.

Make sure you inlcude a battery in the setup, and cover the largest area of your roof you can, plus as big a battery as posisble.

With a decent sized battery, yoy can set your system so that in the winter, the battery is charged at cheap rates, then you use that for your power, rather than taking from the grid at expensive times.

During the summer, the solar should charge the battery durubg the day, and only export when it is full.

You will be best off going with an energy supplier such as Octopus, because they pay decent rates for what you export, and have half-houly variable rates, enabling that cheap overnight charging. You do need a smart meter though to take advantage of this.

We have had a 10.14kW system installed since Feb 2022, with a 16kWh battery, and I reckon payback time is about 8 years. If we had needed a loan to pay for it, then payback would have been longer due to interest payments.

 

[Marchrider]

I was doing some sums on what I might be about to agree too - do they make sense?

18 x 450w Panels = 8.1 kw
for my postcode, roof pitch and orientation south that should produce 6560kwh per annum

plus 2 x 5kwh batteries

From my own way of looking at it (not the blurb with quote or the sales pitch)

If I consider the batteries and panels separately

Charge the batteries every night at 7p per kwh and use the power during the day
this is a saving of 21p per kwh
lets consider the batteries are only 9kwh insted of 10kwh
so over a year 365 x 9 x 0.21 = a saving of £690

Sell all power generated back to the grid for 15p per kwh = £984

this would give a saving of £1,674 per year
cost of system £10,100
= payback 6 years

obviously a bigger saving if we use electric whist producing, so the above is worst case?

Do my addings up make sense ? am I missing something ? sounds a bit too good

 

[ebikeerwidnes]

Certainly get a battery and look at tariffs that give cheaper rates at off peak

Then you can set it up to charge overnight in winter and use it at the higher rates during the day

in summer you obviously can use the solar power stored in the battery during the day

make sure you do your sums very carefully though
I have so far found that even the "everything the same price" from EDF is still better for us than the Octopus version with cheap rates on it at times

ALso keep an eye out for government initiatives - we made a fair bit from the one a while ago - they made it less easy to do with the last version
but worth watching for

Also - make sure your roof is OK before you get panels
you would be sick if you had them installed and had to replace the roof in a year's time - and then have to have them taken down and then put back

 

[Alex321]

I was doing some sums on what I might be about to agree too - do they make sense?

18 x 450w Panels = 8.1 kw
for my postcode, roof pitch and orientation south that should produce 6560kwh per annum

plus 2 x 5kwh batteries

From my own way of looking at it (not the blurb with quote or the sales pitch)

If I consider the batteries and panels separately

Charge the batteries every night at 7p per kwh and use the power during the day
this is a saving of 21p per kwh
lets consider the batteries are only 9kwh insted of 10kwh
so over a year 365 x 9 x 0.21 = a saving of £690

Sell all power generated back to the grid for 15p per kwh = £984

this would give a saving of £1,674 per year
cost of system £10,100
= payback 6 years

obviously a bigger saving if we use electric whist producing, so the above is worst case?

Do my addings up make sense ? am I missing something ? sounds a bit too good

You aren't going to average 15p per kWh for what you export. But prices of the solar panels, batteries & installation have come down over the last 3 years, so you will probably be in a better position than us - we paid a total of around £20K for our system and battery, and although both are bigger than yours, not enough to be twice as expensive.

We just had the statement from Octopus, and for the period 24th Feb to 23rd March, we had total electricity charges (including standing charge) of £48.64. and total electricity credit (for export) of £58.76, so net profit of £10.12. During that time, we consumed 353kWh - which at an average cost of about 27p means it would have cost us £95, so a total gain for one month of about £105. We gain more during the summer, when we turn off the overnight charging, and usually take nothing from the grid, while exporting quite a lot.

 

[Marchrider]

You aren't going to average 15p per kWh for what you export. But prices of the solar panels, batteries & installation have come down over the last 3 years, so you will probably be in a better position than us - we paid a total of around £20K for our system and battery, and although both are bigger than yours, not enough to be twice as expensive.

We just had the statement from Octopus, and for the period 24th Feb to 23rd March, we had total electricity charges (including standing charge) of £48.64. and total electricity credit (for export) of £58.76, so net profit of £10.12. During that time, we consumed 353kWh - which at an average cost of about 27p means it would have cost us £95, so a total gain for one month of about £105. We gain more during the summer, when we turn off the overnight charging, and usually take nothing from the grid, while exporting quite a lot.

is that 15p unusually high ? does it vary between seasons
at the moment export is around 50% of import - is that typical

 

[fritz katzenjammer]

The guy next door dropped a ton on a full system capable of powering his house. He could even sell power into the grid on sunny days and get it back at night on the cheaper off peak rate.

when they were clean

and it wasn’t cloudy

and it hadn’t snowed

we were pretty saddened for him when he found the payback period was roughly the lifespan of the panels.

bet he wished he’d asked that question up front.

 

[Alex321]

The guy next door dropped a ton on a full system capable of powering his house. He could even sell power into the grid on sunny days and get it back at night on the cheaper off peak rate.

when they were clean

and it wasn’t cloudy

and it hadn’t snowed

we were pretty saddened for him when he found the payback period was roughly the lifespan of the panels.

bet he wished he’d asked that question up front.

How viable they are does depend on where you live, and the aspect of your roof.

But in the UK, you will not get that much snow, and you will usually still be generating something even when it is cloudy.

 

[Alex321]

is that 15p unusually high ? does it vary between seasons
at the moment export is around 50% of import - is that typical

Yes to all of those, if you are with a good supplier.

Octopus give better export rates than most suppliers, but even so the average today is only 10p, with a low of 6.7 (14:00-14:30) and a high of 17.94 (18:30-19:00).
For incoming, the average is just above 20p, with a min of 14.7 and max of 40.88 (same periods)

 

[Marchrider]

Yes to all of those, if you are with a good supplier.

Octopus give better export rates than most suppliers, but even so the average today is only 10p, with a low of 6.7 (14:00-14:30) and a high of 17.94 (18:30-19:00).
For incoming, the average is just above 20p, with a min of 14.7 and max of 40.88 (same periods)

I don't quite get this with Octopus's tariffs, they seem to have "Agile" that has an average export at 10p per kwh, or a "Fixed" tariff of 15p, Yes the Import is higher with the "Fixed" tariff, but since most of our electric via the battery at 9p then i think i would prefer the fixed.

The guy next door dropped a ton on a full system capable of powering his house. He could even sell power into the grid on sunny days and get it back at night on the cheaper off peak rate.

when they were clean

and it wasn’t cloudy

and it hadn’t snowed

we were pretty saddened for him when he found the payback period was roughly the lifespan of the panels.

bet he wished he’d asked that question up front.

I have considered the longevity, the panels themselves are not too bad - £92 each and should generate (for where we live and roof orientation) £54.67 per year, so the solar panels have a pay back of 20 months (obviously a labour charge would make that longer) and the panels should last 10 years

The inverter is the worry at a thousand quid.

 

[king of the mole hills]

All my panels have there own inverter seem a lot more efficient
I pay 18 fixed and sell for 15 fixed with octopus

 

[Marchrider]

All my panels have there own inverter seem a lot more efficient
I pay 18 fixed and sell for 15 fixed with octopus

18 fixed ? i'm on 23.15 (don't have a smart meter yet)

 

[king of the mole hills]

18 fixed ? i'm on 23.15 (don't have a smart meter yet)

Yes in the south east near battle octopus fitted my panels

 

[yello]

It's the 'return on investment' question (and let's face it, many of us are somewhat understandably forced into that self-serving and short-term perspective) that has me questioning solar panels as a project. There are broader benefits of course.

 

[king of the mole hills]

Apparently they do help when you sell your house as new buyers save a few quid
So in the end all is good hopefully