My solar array doesn't seem to generate enough energy

[agybag]

Hi,
I've recently had a 4KW PV array fitted in March this year however I don't believe it's producing the expected results. Yesterday 29/06/2019 was the hottest day so far with cloudless skies and the system at noon peaked at 2.2KW. I would expect to achieve around my peak which is set at 3.8KW. Is my system faulty and should I have the installers check out the system for any possible issues or am I expecting too much from the system ?

 

[littlespark]

It'll depend on the angle of the roof... the angle to the sun and any tree branch obstruction.
3.8 kW is the maximum you can generate in 100% perfect conditions.

2.2 is probably about right, not knowing the circumstances.

Also, is 2.2 the kW reading off the inverter, or off another energy monitor which may be reading generation MINUS what's being used in the house

 

[agybag]

It'll depend on the angle of the roof... the angle to the sun and any tree branch obstruction.
3.8 kW is the maximum you can generate in 100% perfect conditions.

2.2 is probably about right, not knowing the circumstances.

Also, is 2.2 the kW reading off the inverter, or off another energy monitor which may be reading generation MINUS what's being used in the house

 

[agybag]

Thanks for the reply,
Conditions on the day were perfect with no obstructions and south facing. 14 x315 watt panels fitted and readings taken via a solo 11 and a wattson monitor with only a difference of 30 watts between them. Max generated was around 2.2 KW which I'm sure is way under the predicted output. Since this is a new system and still in warranty I just want to ensure the output is reasonable (I expected a higher output) on a mid summer's day with no obstructions.
Regards
John

 

[littlespark]

Next time im in my attic, i'll have a look and see what my 4kW system is kicking out...

It may be you have a faulty panel which is acting as resistor to the others.
Don't go pulling out any cables.... !

 

[agybag]

Next time im in my attic, i'll have a look and see what my 4kW system is kicking out...

It may be you have a faulty panel which is acting as resistor to the others.
Don't go pulling out any cables.... !

Thanks it's appreciated

 

[alasdairp]

I had one thought - could it have been limited by a high SSE network supply voltage in the area and a relatively low demand for extra power? The inverter cannot keep just pushing up the local supply voltage in order to drive out its "rated full power". Some SSE areas (and elsewhere in the UK!) run at 240 to 245 Vrms normally. The inverter will almost certainly be designed to feed a 230 volt (harmonised! ha!) supply system. As the power monitor shows generated power, did you apply some extra loads (electric fan-heater, kettle, etc) to the house wiring to see if the generated power increased? Worth trying.

I have seen serious examples of problems like this when some new bio-fuel electrical generation plants start up in lightly loaded areas in the summer - areas without adequate 11kV/33kV infrastructure to pass out the power to other areas. In one case in Cambridgeshire an 11 kV substation had to be expanded to also be a 33 kV substation to prevent regular voltage excursion exceed 253 Vrms (and often up to 258 Vrms!). I think similar problems are now becoming more common in some areas with large solar power farms. It also can occur with windfarms at times of high (good) wind and low consumption. National Grid had to regularly pay wind-farms (£10s million per year) to under-generate in order not to exceed maximum permitted system voltages.

 

[agybag]

I had one thought - could it have been limited by a high SSE network supply voltage in the area and a relatively low demand for extra power? The inverter cannot keep just pushing up the local supply voltage in order to drive out its "rated full power". Some SSE areas (and elsewhere in the UK!) run at 240 to 245 Vrms normally. The inverter will almost certainly be designed to feed a 230 volt (harmonised! ha!) supply system. As the power monitor shows generated power, did you apply some extra loads (electric fan-heater, kettle, etc) to the house wiring to see if the generated power increased? Worth trying.

I have seen serious examples of problems like this when some new bio-fuel electrical generation plants start up in lightly loaded areas in the summer - areas without adequate 11kV/33kV infrastructure to pass out the power to other areas. In one case in Cambridgeshire an 11 kV substation had to be expanded to also be a 33 kV substation to prevent regular voltage excursion exceed 253 Vrms (and often up to 258 Vrms!). I think similar problems are now becoming more common in some areas with large solar power farms. It also can occur with windfarms at times of high (good) wind and low consumption. National Grid had to regularly pay wind-farms (£10s million per year) to under-generate in order not to exceed maximum permitted system voltages.

I'm having the engineer who installed the system over Friday morning to check the system for faults. I should say as of yesterday the solar stopped generating for no apparent reason and the meter stopped flashing but now seems to be generating again. The red light on the meter would usually flash around once every 3-4 seconds but now only flashes around once a minute. There is for sure a fault in the system

 

[Deleted account]

I had one thought - could it have been limited by a high SSE network supply voltage in the area and a relatively low demand for extra power? The inverter cannot keep just pushing up the local supply voltage in order to drive out its "rated full power". Some SSE areas (and elsewhere in the UK!) run at 240 to 245 Vrms normally. The inverter will almost certainly be designed to feed a 230 volt (harmonised! ha!) supply system. As the power monitor shows generated power, did you apply some extra loads (electric fan-heater, kettle, etc) to the house wiring to see if the generated power increased? Worth trying.

I have seen serious examples of problems like this when some new bio-fuel electrical generation plants start up in lightly loaded areas in the summer - areas without adequate 11kV/33kV infrastructure to pass out the power to other areas. In one case in Cambridgeshire an 11 kV substation had to be expanded to also be a 33 kV substation to prevent regular voltage excursion exceed 253 Vrms (and often up to 258 Vrms!). I think similar problems are now becoming more common in some areas with large solar power farms. It also can occur with windfarms at times of high (good) wind and low consumption. National Grid had to regularly pay wind-farms (£10s million per year) to under-generate in order not to exceed maximum permitted system voltages.

Wow didn’t know that could happen.

 

[JimmyTheJock]

Hmm. Have a read of the specification for the pv panels you have installed and especially their operating temperature. Not unusual to find lower output on very sunny days especially if there is little or no wind. I suspect you'll probably find you get maximum output around April or May and again in the autumn when it is a sunny but cool day.

 

[agybag]

Hmm. Have a read of the specification for the pv panels you have installed and especially their operating temperature. Not unusual to find lower output on very sunny days especially if there is little or no wind. I suspect you'll probably find you get maximum output around April or May and again in the autumn when it is a sunny but cool day.

Hi,
As mentioned in my first message I've had the system installed since March and never been able to generate more than 2.2 KW and that's been the max ever generated. The promise of up to 3.8 KW and at 2.2 KW it's falling well short of the expected peak of 3.8 KW. I have a clear view with no obstructions and facing south with the sun around noon coming directly into my living room.
Regards
John

 

[R-fur]

I agree with Alisdairp. Check the voltage if you know how to do it safely. I was at a farm once that had installed two wind turbines but they would not generate as the local voltage was too high. They had to write to SPEN to complain about the voltage. Eventually they adjusted the taps at the pole mounted transformer to reduce the voltage.

 

[agybag]

Hmm. Have a read of the specification for the pv panels you have installed and especially their operating temperature. Not unusual to find lower output on very sunny days especially if there is little or no wind. I suspect you'll probably find you get maximum output around April or May and again in the autumn when it is a sunny but cool day.

Just checked it a moment ago and the incoming voltage is 242.5 volts

 

[agybag]

Just checked it a moment ago and the incoming voltage is 242.5 volts

How do I go about having the voltage reduced ?

 

[R-fur]

242V should be ok. I would expect the inverter to have its upper voltage set at about 250V