Low Solar readings

Yoshii

Hi
Over the past 2 months my 4kwh solar system has been giving readings of 1-1.3kwh even in full direct sunshine and the panels have just been generating 4-6 kwh for past 2 months.

Is this normal for time of year?

Any help appreciated.

Yoshii

Yoshii

Sorry I mean that they have been generating 4-6 kwh daily even in days of lots of sunshine.

System

Not a lot of information to go on but, FWiW, my 2.115Kwp system had a target PVGIS figure of 181Kwh last month and I achieved just under 200Kwh. My roof panels are orientated slightly East of South with low level obstructions only. My target for a 12 month period is 1940Kwhs which I achieved last year: Sep to Aug.

matelodave

Don't forget that the sun is getting lower in the sky - panels will only generate their maximum when directly facing the sun so ideally they need to track the sun both horizontally and vertically.
Obviously most panels don't so they should ideally be set up at an optimum angle and direct to maximise their output over the whole year.
Frequently this is not possible so if your roof isn't facing directly south or the angle is fairly shallow then the output will drop off quite dramatically as the sun gets lower in the sky.

Fruit_and_Nut_Case

OP: If you haven't already, enter your data HERE and see what you should be expecting.

Martyn1981

Yoshii wrote: »

Hi
Over the past 2 months my 4kwh solar system has been giving readings of 1-1.3kwh even in full direct sunshine and the panels have just been generating 4-6 kwh for past 2 months.

Is this normal for time of year?

Any help appreciated.

Yoshii

Would need more info, but that doesn't sound right.

What is the orientation and roof pitch, and if you don't mind rough location (nearest town).

Does your system have 2 strings, is it possible that only one string is working. Does the inverter display output for the two strings for you to compare?

Are all the panels facing the same direction? If they face different directions, are the differing arrays on separate MPPT's, or do they 'compete' with each other, with the higher performing system being dragged down by the lower performing?

What was your total generation for September, how did it compare to PVGIS (as recommended by Fruit and Nut)? There's a walkthrough for the site in section 5 of the PV FAQs.

Lots of thoughts, but gut feeling, something is wrong.

Mart.

Martyn1981

matelodave wrote: »

Don't forget that the sun is getting lower in the sky - panels will only generate their maximum when directly facing the sun so ideally they need to track the sun both horizontally and vertically.
Obviously most panels don't so they should ideally be set up at an optimum angle and direct to maximise their output over the whole year.
Frequently this is not possible so if your roof isn't facing directly south or the angle is fairly shallow then the output will drop off quite dramatically as the sun gets lower in the sky.

Very true, but 4-6kWh from a 4kWp system seems low, especially if 'the last two months' included some of August.

Even my 2kWp 30d pitch WNW has clocked up 5 4kWh's this month (ok, one was 3.7, but the others 4.1 to 4.9).

[Edit: Quick check for Sept, and 2kWp WNW hit or exceeded 4kWh 21 times, and exceeded 6kWh 6 times. M.]

Mart.

Yoshii

Wow thanks for your advice. I thought my generation figures were low and so i have been proved correct. I will use the website given and see what happens...But you have all helped

Thanks

Yoshii

Yoshii

In the past 2 months there has been very bright sunshine at 12 noon and the reading has been 1.3 kwh and then it will cloud over and the reading is 0.8kwh. I do not understand

Andy_WSM

If there are shadows or shading on ANY of the panels it will affect the performance of the whole system.

Is anything in the line of sight between the Sun & your panels? Any shadows at all?

Cardew

Agree with the above - shading is the first thing to suspect.


What was the output in June/July?