Solar Panels

[Boathook]

I've got 2 solar panels, 50 and 30 watt, both Spectra semi flexible. The 50 was fitted in 2016 and the 30 in 2019. The other day I thought output was down so disconnected one at a time and monitored the change in output on my victron connect app on my phone. This indicated that the 50 watt panel was giving the same wattage as the 30. I will be doing a few more checks in a week or so using a test meter just to confirm results.
I thought spectra was a good make but now not to sure seeing that the panel is only around 6 years old, or is 6 years good for a panel ?

If it is failing I will replace it so any ideas as to best make or company to deal with. Also is a rigid panel better than a semi flexible ?
I will also replace the small panel as both are on the same flat surface so I will need to measure total space available for a new panel.

I have over the years, read on here some members buying cheap and others expensive and some having good results and others bad. My experience of cheap for anything means that the item breaks, packs up, etc.

Edit. Altered the date for the 50 watt panel to 2016 from 2019.

 

[LadyInBed]

6 years for a semi sounds about right.
I went from semi's to rigid, the new generation ones are much better, and cheaper per watt.

 

[Boathook]

6 years for a semi sounds about right.
I went from semi's to rigid, the new generation ones are much better, and cheaper per watt.

Which brand ?

 

[Aeolus]

The panels are, according to the OP, only 3 years old. if they have deteriorated in that time then clearly questionable quality.

 

[Boathook]

The panels are, according to the OP, only 3 years old. if they have deteriorated in that time then clearly questionable quality.

Made a mistake on the 50 watt panel. Actually fitted in 2016. Hadn't noticed mistake until you mentioned it.

 

[VicS]

Made a mistake on the 50 watt panel. Actually fitted in 2016. Hadn't noticed mistake until you mentioned it.

You say the two panels were giving the same output when tested individually .... maybe that was because that was all the battery was accepting

Measure the open circuit volts and the short circuit current (using the 10amp range on your multimeter) of the panels individually How do they compare with the figures in the Spectralite brochure.

 

[William_H]

If buying a new panel you might find you have room for one large dommestic PV panel. ie typically about 180by 50cms. These are very cheap for wattage you get and at 40v or more open circuit voltage may be OK for your MPPT controller but definitely rigid. PS not much help to you but around here s/h domestic PV panels are really cheap. Due to house demolition large uptake of domestic PV and not allowed to reinstall s/h panels to mains grid. ol'will

 

[DipperToo]

I am still learning about connecting multiple panels, but if my understanding is correct, if 2 panels are connected in series, then the lower voltage panel takes precedence if the panels are dissimilar so the other panel will never give its full output? I was also advised to put a blocking diode in each panel when connected in series as well.
Please correct me if this information is not correct.

 

[Boathook]

I am still learning about connecting multiple panels, but if my understanding is correct, if 2 panels are connected in series, then the lower voltage panel takes precedence if the panels are dissimilar so the other panel will never give its full output? I was also advised to put a blocking diode in each panel when connected in series as well.
Please correct me if this information is not correct.

Mine are in parallel. It was why I purchased the same make a few years after the first one following discussion with Marlec. This provided the most 'power' for where it was mounted, as it could be partially shaded. The panels have blocking diodes built in but the controller (Victron blue tooth) stops any discharge as well.

 

[VicS]

I am still learning about connecting multiple panels, but if my understanding is correct, if 2 panels are connected in series, then the lower voltage panel takes precedence if the panels are dissimilar so the other panel will never give its full output? I was also advised to put a blocking diode in each panel when connected in series as well.
Please correct me if this information is not correct.

Two panels in series will give an array with the sum of their individual voltages, ie two 12 volt oanels will give 24 volts, but they should be the same power (watts) otherwise combined they will be limited to twice the power of the smaller one . Only one blocking diode is required but the panels may already have them.

Two panels in parallel must be the same voltage but need not be the same power. Combined they will have the same voltage but the sum of their individual powers.
Blocking diodes may be needed in each panel if they are not already fitted

Are you sure you know the difference between series and parallel ? Your post suggests that you may have them muddled.

 

[Boathook]

You say the two panels were giving the same output when tested individually .... maybe that was because that was all the battery was accepting

When both connected the output wattage doubled according to the Victron controller. Both were giving around 7 watts each hence my assumption. Not much power but they are lying flat, and at the time the sun was low. As mentioned I will do more checks but want to increase solar power so an upgrade and more square metres of panel will be happening this winter or sooner.

 

[DipperToo]

.......

Are you sure you know the difference between series and parallel ? Your post suggests that you may have them muddled.

View attachment 141895

Thanks - you have clarified the primary difference when mixing panels of a different voltage/wattage in series or parallel configuration. Yes, more than familiar with series/parallel but it was the panel behaviour in each configuration which I had somehow got the wrong way round! Appreciate the correction.

 

[GHA]

Thanks - you have clarified the primary difference when mixing panels of a different voltage/wattage in series or parallel configuration. Yes, more than familiar with series/parallel but it was the panel behaviour in each configuration which I had somehow got the wrong way round! Appreciate the correction.

slight aside, some on here before have said put the panels in series so a victron mppt turns on earlier - panel voltage needs to be 5v above battery voltage for the controller to turn on. Incorrect, - takes only a few mA for a 36 cell panel to get the voltage high enough open circuit and turn on the victron. Nothing to be gained going to series on that front.