Solar Panels, cold callers and increased performance

[toastyhamster]

Had some panels fitted around 3 years ago, generally quite happy with them, had a great first year of payments followed by a couple of average ones, long term investment etc etc

Yesterday had a doorstop cold call claiming they can change the inverter and add a new "thing" which would increase output by around 25%.

Had a bit of a google and it would appear to be real (depending on what i already have), but it would need to be pretty cheap to justify it, 25% on a poor year is only about 150 quid and as they have to replace the entire inverter as well I guess it's going to be well north of 1k (my current inverter looks to be about £950).

Anybody looked into this further?

[4Q]

Scammers, there's nothing you can do to increase output by 25% if it's correctly installed. They're probably trying to sell you voltage a optimiser which manages the mains voltage to your inverter, although this only has an effect if your supply voltage regularly goes above 252 volts which it shouldn't, your inverter manages fluctuations in mains voltage pretty well on its own. These companies are currently being investigated by trading standards and MCS.

BTW, Solar is my thing, I've been consulting, designing, installing and teaching PV for over 12 years.

[toastyhamster]

The googling I did suggested that the entire system runs to the lowest panel output? Is this also a scam?

i was going to call the original installers who were very good but I guess you saved me a job - thanks.

[4Q]

Sort off, but if they are a decent panel they should be within 3% of each other anyway (usually up to plus 3% not minus). In real world usage the difference in each panel performance is so close as to not make any difference whatsoever to the overall yield of the system.

The only way you're going to optimise for panel discrepancies is to fit an optimiser like Solar Edge to EVERY panel along with a replacement inverter to manage them, even then the gains are very small so not worthwhile in the vast majority of installations. As this would involve scaffolding the house and removing the panels from the roof it's just not worth the additional cost.

As I've already said, they're likely snake oil salemen scamming you into buying something you don't need.

[Chrisgr31]

On a similar subject we had solar panels installed a couple of years ago. One of the selling points the monitoring system and that they would be remotely monitored by Enphase who could notify if there was a problem.

It's monitored using the Enphase Envoy, the only problem being it's stopped working. Apparently we need a replacement one and they are £300. Endless. To say we were told the system has a 25 yr warranty but it turns out the Envoy is onl warranted for 2 and it did 3. Do we actually need it or can we trust the panels and inverter just to the job.

[Noslek]

I believe it depends on your set up and any shading of your panels. If you run a single inverted and have your panels in a string, the best output is limited to the worst performing panel in the array. If like me (and I suspect the person above) you are using the enphase system with micro inverters (a small very efficient inverter per panel), then each panel delivers independently and therefore at its own best rate irrespective of the rest. So if some panels are in shade, some in bright sun, only those in shade would produce at a lower rate (which is part of the reason I went the micro inverter route)