To optimise or not

mcn99

Hi,

After really struggling to get quotes, finally have got a decent quote for a non optimised 9kw system.

But I'm struggling to decide whether to go for optimisers.

I don't really have much shading on my roof, i have single roof which is south facing, I do have some trees on east and west, but these would only affect panels for a short period of time

Unfortunately the installer has suggested solar edge optimizers plus solar edge inverter, additional cost is £1.3k.

So question is, if shading isn't that bad, is it really worth optimizing all the panels.?

Thanks

Spies

Are you looking for it to repay itself? 

QrizB

mcn99 said:

So question is, if shading isn't that bad, is it really worth optimizing all the panels.?

I wouldn't bother with optimizers if there's no shade for most of the productive hours. If the money was burning a hole in my pocket, and I had room on the roof, I'd buy more watts instead.

mcn99

question really is, will it reduce the overall payback time ? If it does then I don't mind forking out the extra money.
(not sure i really want more panels 9kw is enough)

Spies

What's the overall cost without optimisation?

mcn99

9.6k for 9kw system with water heating diverter, non solar edge invertor.

1.3k extra for solar edge invertor/optimisers

Spies

So you would need to generate an additional 15% for it to pay for itself, with minimal shading I can't really see that happening. 

QrizB

mcn99 said:

question really is, will it reduce the overall payback time ? If it does then I don't mind forking out the extra money.
(not sure i really want more panels 9kw is enough)

9kW of panels in a good position will produce around 9000kWh/yr. From what you've described, your shading (if in fact there is any) won't lose more than 10% of that - about 900kWh.

Assume you get a great export tariff of 10p/kWh (achievable on Octopus Outgoing Agile in recent months). Those 900kWh will be worth £90 per year. Payback for your £1300 will take almost 15 years.

Or you could achieve an equivalent increase in output by adding another 1kW of panels. How much would that cost?

Or you can make do with generating 10% less and spend the £1300 on eg. a stake in the Ripple wind farm or a holding of UKWIND in a SSISA (this is not investment advice).

OOA in my region for past year, from https://www.energy-stats.uk/octopus-agile-outgoing-export-southern-england-2/

2nd_time_buyer

In my case, currently there is little shading on the (side) roof. However, quite a few houses in the area are having hip-to-gable loft conversions which would cause some shading issues. I am not sure what the neighbor's intentions will be over the next 25 years. However, I know I would be OCD worrying about what they might do. So the extra £1000 upfront seems a fair price for peace of mind. I guess it will be at least double that to retrofit.

mcn99

I only have trees to worry about. The shading wont really increase (trees are all mature).

2nd_time_buyer

 ... the other argument is that you can monitor how each panel is performing and detect any problems e.g. a broken panel, or pigeon !!!!!! on the panel.

However, my guess is that the panels are less likely to go wrong than the optimisers over a 25 year period. Which would make it !!!!!!-over-tit logic.