Solar panel performance: claimed vs actual

[Zave]

As I've just installed a charge controller that can give me readings I've all of a sudden become obsessed. I thought I'd start a thread were we state as follows:

Panel:

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

12V solar panel solar charging kits for motorhome caravan boat campervan yacht marine off-grid

www.photonicuniverse.com

Stated watts: 160

Maximum actual watts recorded: 101

Age of panel at that time: 3 years old

Method of recording: 75-15 version

SmartSolar MPPT 75/10, 75/15, 100/15 & 100/20 - Victron Energy

Maximize the energy-harvest, driving it intelligently to achieve full charge in the shortest possible time using the SmartSolar MPPT. Learn more now.

www.victronenergy.com

 

[Dellmassive]

A few things to remember when your testing.

The rated Watts is against test conditions..... Which will only be achieved in a test situation.

So in the UK expect 50% to 75% of the rated power.

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Also to generate max power you need some where for the power to go.... Your Victron is showing a adoration stage, which will be current limiting.

So to get the most out of the panel, switch on some loads to drag the battery down and force the Victron into BULK mode....

That should give you max power.

The other way to test is to measure the voc of the panel.

Then dead short the panel and measure the short circuit current.

Then compare to the spec plate.

 

[Deaky]

Here’s mine today.
250w panel, I’ve never seen it much higher than this.

 

[Dellmassive]

So... 700w worth of panels.

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Got me just under 400w of power.

I'll take that.

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With today's full sun...

And panels not angled optimally.

 

[Salty Spuds]

Solar panel ratings are like car manufacturers MPG ratings, to be taken with a large pinch. As Dell says, the rating is output under ideal conditions, which rarely if ever will happen. The panel has to be at 90deg to the sun, not overheating, cloudless sky yada yada. I have a 160W panel & the best I’ve managed on a 7 week European trip is 113W. Personally I think anything over 75% of the rated output is good going.
My 4KW home PV system has only actually reached 4KW twice in 12 years.

 

[davecdjt]

So... 700w worth of panels.

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View attachment 203418View attachment 203419

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Got me just under 400w of power.

I'll take that.

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With today's full sun...

And panels not angled optimally.

Lee, I see you have the microinverter. The advertising for the balcony power and home solar concept seems to imply that you can charge your power station through the day and feed the power back into your home at night running stuff off your free energy, who does that work? I can't see an explanation of what I understand to be implied in the various videos I have watched. Maybe they assume a level of knowledge I don't have or else I have totally misunderstood the product. If I had the EF microinverter and added it to my 160w panel and River 2 pro how does it feed the power back into power my running devices? I'm not sure if that question makes any sense. If it doesn't I'll bring you a
beer at the T6F summer camp and ask again.

 

[Zave]

So to get the most out of the panel, switch on some loads to drag the battery down and force the Victron into BULK mode....

That should give you max power.

The other way to test is to measure the voc of the panel.

Then dead short the panel and measure the short circuit current.

Then compare to the spec plate.

Ah. Not as simple as I'd thought!

 

[Shaun Witts]

Lee, I see you have the microinverter. The advertising for the balcony power and home solar concept seems to imply that you can charge your power station through the day and feed the power back into your home at night running stuff off your free energy, who does that work? I can't see an explanation of what I understand to be implied in the various videos I have watched. Maybe they assume a level of knowledge I don't have or else I have totally misunderstood the product. If I had the EF microinverter and added it to my 160w panel and River 2 pro how does it feed the power back into power my running devices? I'm not sure if that question makes any sense. If it doesn't I'll bring you a
beer at the T6F summer camp and ask again.

I’ve also been waiting for Lee to post his usual in depth review of that microinverter for the same reasons - I don’t get how it works.

 

[Martinf]

I think that for some reason the panels on vans are less effective than fixed ones on house roofs. Just for example my house panels maxed out today at 87.7% of rated value. Last Thursday it was 95.3%. Sometimes it shows over 100%. Domestic load is small with most being exported.

Yet on our vans even when parked in the the appropriate orientation the percentage is much less. Perhaps I just need a higher tilt on the roof!

 

[Pete C]

We have a folding solar panel rated at 120W. Best I have seen is 95w on a properly sunny day, with the panel oriented as close as face on to the sun as I could manage.

Pete

 

[Dellmassive]

The PowerStream has been arriving in bits and bobs...

The main unit arrived yesterday....

So brand new and testing yesterday.

I'll be doing a review soon.

In a nutshell you can connect panels upto It. ( PV input 11,-55v 13A )

And it will push upto 800w into your house...
IV witnessed this by watching the house smart meter.... So effectively the electric I'm paying for is being reduced by the amount I'm self producing.

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When you add a battery pack.... EF delta2 in my case, you can set the priority.

So fully charge battery, then back feed house. ( Charge level parameter adjustable)

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Or push all power to the house, including from the battery pack. (Which depletes the battery fairly quickly)

And for safety when the PowerStream is unplugged from the wall it shuts down instantly.

So far it's looking like a good way to use spare panels I have that are not doing nothing.


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[Martinf]

And it will push upto 800w into your house...

That’s an interesting one. Is this via the “Smart plug” mentioned in the screenshots? I didn’t think this was a sensible or even permitted option without an integrated inverter. Could it not cause problems with the MCBs and RCDs and potentially hazardously back feed the mains during an outage?

I’d have a possible occasional use for that option though.

 

[Dellmassive]

The unit itself is a micro inverter that's grid tied.

So it samples the mains all the time and locks onto it...if the mains goes off the unit shuts down.

I'm lead to believe that 800w is the max you can have for a grid tie inverter. Above that it need to be hard wired in as you say. (This is a hot topic and needs clarification)

The smart plug is just a EF WiFi plug that reports back the wattage of the connected appliance....so just an extra.

 

[roadtripper]

It's not the maximum as such, my grid tie inverter is 3.6kW, but 800w is the limit of what you are allowed to back feed to the grid without notifying your DNO at all.

This means if you already have fixed solar then plugging this in is extending your contribution, and that needs notifying. Also you need to notify should you use more than one.

If it takes your generation over 3.68kW then you need to notify and get clearance before plugging it in, over 3.68kW the DNO is permitted to tell you no if it causes issues with local power regulation.

Almost every home solar is 3.6kW for this reason (or if over sized limits itself to that level and diverts the rest to battery) so under the regs if you have solar already you almost certainly need to notify and get permission before using this.

Connecting generation to the electricity networks

This page is for those looking to connect generation to the electricity networks.

www.energynetworks.org

Those are the regs, the other thing to consider if you have an existing solar installation is if it is either a battery system and/or an over sized one that self limits export to the grid it will be doing this by a connection to the smart meter or a current clamp near a normal meter to measure electricity flow in and out. If you put an "extra" 800 watts in that the main system doesn't know about then that may confuse things.

 

[Jamie89]

@Dellmassive granted July was a bit wet, but how did your testing go with the Powerstream?

 

[Dellmassive]

The power stream is a great introduction to domestic solar.

800w hybrid inverter is very small in the grand scheme of things. .. but still a great introduction.

I think they have pulled the plug on UK sales, for the time being.... I'm to believe that's due to the way it connects to the house mains.

But whatever.it's shown me the way of domestic solar. It's lead to me doing a upgrade with more panels, new hybrid inverter, and battery storage.


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