Why a drop in monies

I could write on the back of a stamp what I know about PV and could do with some help...

One of our friends (recently divorced so hasn't really dealt with this before) has noticed that the payment from the supplier is much less than last summer. Given that we have had a decent amount of sun this year she is concerned about the drop.

So what do I know?

The inverter is a sunny-boy

Their package was bought outright - a long time ago

Sorry if that isn't that helpful

Over to you....

Thanks

Drop in kW generated or monies paid/kW?

Good points and questions, keep them coming and I'll get some answers....

some more details on the system would be useful along with any pictures you can get. As paddler said, if there is a fault with the inverter it should show on the screen as an error message. The other possibilty is filthy panels. Depending on the roof pitch, and location close to trees, flight paths of birds, panles can get really dirty during the drier summer months with subsequent drop in performance.  A wet summer can be better for output than a dry one oddly enough.

these are good gadgets. Most inverters are shoved in attics with the generation meter in a cupboard/ garage / attic as well, so it is really easy to miss a system that is failing.

http://www.geotogether.com/products/solar-monitoring/

Canoeboy said:

 i had one where the builders next door to a house with PV made enough vibration through building work over a month, the DC plug worked out and full onto the floor)

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I fitted a system next to the hotel that inspired Faulty Towers. This has now been demolished to build flats. The builders have been pile driving for months and it seems the system has failed, so it will be very interesting to see what has happened to the system.

Ok. Managed to get some more information:

 12 panels, size 3, Monocrystalline Sharp 240's

inverter type :string

cleaned about 2 months ago

Readings for last 18 months:

Feb-15 7678 7921 gives 243

Jun-15 7921 8867 gives 946

Sep-15 8867 9840 gives 973

Dec-15 9840 10252 gives 412

Mar-16 10252 10377 gives 125

Jun-16 10377 10816 gives 439 so a drop of 507 compared to same quarter last year

Sep-1610816 11263 gives 447 so a drop if 526 ditto

Does this help.

Thanks for your ideas and input so far....

Any new shading??

A tree grown a little since last year now shading??

I don't think so. As far as I can remember there are no trees

Could it be something as simple as a detached/damaged cable half way along string?

i know very little of solar merely looking at obvious?

loft too hot and inverter shutting down?

Andy™ said:

loft too hot and inverter shutting down?

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That's an interesting idea.

How hot it too hot?

Interestingly enough my loft is a lot cooler now that I have solar due to the panels totally covering my south facing roof.

have had one fault in my system, 6 months ago, was a corroded crimp on the roof, causing numerous shutdowns of the inverter.

I just checked the feed in tariffs for last sept and this sept and they are in line with the drop you are getting. From here  https://www.ofgem.gov.uk/environmental-programmes/fit/fit-tariff-rates

this sep-last sep in screen below



I might be wrong though as I have literally no idea about any of this.

Edit; wait, I thought the figures quoted earlier were pounds sterling not KW, think I have made a mistake again.

Rob_the_rich said:

I just checked the feed in tariffs for last sept and this sept and they are in line with the drop you are getting. From here  https://www.ofgem.gov.uk/environmental-programmes/fit/fit-tariff-rates

this sep-last sep in screen below

View attachment 7411

I might be wrong though as I have literally no idea about any of this.

Edit; wait, I thought the figures quoted earlier were pounds sterling not KW, think I have made a mistake again.

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good investigation work there @Rob_the_rich but those figures are for new sign ups

Once you are registered for FiT's you stay on the rate you signed up at.

Sharp panels are good, so unlikely to be them. 1 string down a possible, but I would suspect a failing inverter  - need make and model number.

Ok guys got some more information:

MCS Certificated Product Name: NU-R240J5
MCS Certificated Product Manufacturer: Sharp Electronics (UK) Ltd
MCS Certificated Product Number: MCS PV0007/37
Technology Type: SOLAR PHOTOVOLTAIC
Estimated Annual Generation (kWh): 2293.00
Declared Net Capacity (kW): 2.88

The install was one of the first (at the highest rate)

Not been to her house yet - wanted to get a few pointers first.

Many thanks for all the input so far guys

Murdoch said:

Not been to her house yet - wanted to get a few pointers first.

Many thanks for all the input so far guys

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check the inverter display for error codes and panles for cleanliness, if yor friend is on the higher tariff then it was fitted a few years ago, and of the panels haven't been cleaned then dirt can build up. Pictures of the array would be good.