Fitting a 300 Watt solar panel on the roof?

[StitchUp]

I have the space for a 300 watt solar panel on our motorhome. I already have a 100 watt panel that feeds into a Victron 100/20 SmartSolar Charge Controller.

This is the panel I'm considering:

300 Watt Panel

Is this okay or am I making a mistake? Any other considerations, thoughts or recommendations?

Thanks

John

 

[Two on Tour]

Try this panel, its nearly half the price of the one you're looking at on Amazon.
Funster Wissel has been buying and fitting these to customer's vans.

295W Smaller Size Perlight Total Black Delta Mono Percium Solar Panel. Delivery from £33 - 54 cell smaller 1.5m size - great for vans and motorhomes, MCS Approved - The Installers choice - - 30 year parts & performance warranty

www.bimblesolar.com

 

[Guigsy]

I'm assuming you're planning on putting both panels through the existing Victron controller? Different solar panels will provide different voltages, depending on conditions. Depending on how you wire them (parallel or series), they'll affect each other in different ways. One will current limit or voltage limit the other because they aren't matched. You're going to get a lot less than 300w less additional power. In cases where the size of the panels are significantly different, you may actually find that you get more power when the smaller panel is removed from the circuit.

EDIT: More info here: https://solarpanelsvenue.com/mixing-solar-panels/

 

[Stealaway]

You are going to need at least 4mm cable's into the controller and a 30amp fuse / breaker. Will you join them on the roof?. It's a big pane for the wind to get under,l make sure it's well fastened down.

 

[autorouter]

It's not a good idea to connect a 100W and 300W panel to the same controller. The voltage of the 100W panel will probably be around 18 to 22V, and the 300W panel is likely to be 35 to 40V. If you feed them to separate controllers, then send the controller outputs to the battery, that is a much better idea.

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[StitchUp]

It was clearly worthwhile asking the question - thanks for all the advice/suggestions

I might get in touch with Funster Wissel.

 

[Two Owl Ones]

I have the space for a 300 watt solar panel on our motorhome. I already have a 100 watt panel that feeds into a Victron 100/20 SmartSolar Charge Controller.

This is the panel I'm considering:

300 Watt Panel

Is this okay or am I making a mistake? Any other considerations, thoughts or recommendations?

Thanks

John

i have just fitted two 175w victron solar panels with an mppt controller to our moho,you may be better to keep everything the same make rather than mix and match, maybe sell the 100w panel and put two 300w from the same supplier and maybe add a larger mppt controller. if you have the space on the roof why not make the best of it ?

 

[footscray188c]

Support the panel in the middle of the longest side . Or the glass surface could shatter been there done that.

 

[Murrays]

Try this panel, its nearly half the price of the one you're looking at on Amazon.
Funster Wissel has been buying and fitting these to customer's vans.

295W Smaller Size Perlight Total Black Delta Mono Percium Solar Panel. Delivery from £33 - 54 cell smaller 1.5m size - great for vans and motorhomes, MCS Approved - The Installers choice - - 30 year parts & performance warranty

www.bimblesolar.com

I fitted the previous (270W) version of this Perlite panel a couple of years ago, it was the highest output I could get in the space. I used a 20A EPever mppt controller also from Bimble. I'm very happy with it as a compact low cost setup with Bluetooth monitoring. The panel is mounted with 6 plastic brackets and a tube of CT1 and it's not going anywhere.
I left the existing 100W panel and it's PWM controller alone for the reasons stated above by Autorouter - different voltage and output current characteristics.

 

[Phoenix2023]

I have the space for a 300 watt solar panel on our motorhome. I already have a 100 watt panel that feeds into a Victron 100/20 SmartSolar Charge Controller.

This is the panel I'm considering:

300 Watt Panel

Is this okay or am I making a mistake? Any other considerations, thoughts or recommendations?

Thanks

John

Check the controller specs, Ive got the same controller and I think when I was sorting out panel config its max is 290w of panels if I read it right, the extra wont hurt it but you lose the benefit of anything over that so the 100w would become dead weight. Ive just bought the perlite mentioned below, I was eying it up but concerned it was too cheap til I read the recommendation in another thread, it is £139 inc VAT and £39 delivery (2-5 days), slight discount with different payment option. I dont mind wasting 5w especially with the good price, but if you want both panels you might need the 100/30. Anyone feel free to correct me if Im wrong!

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[Raul]

Support the panel in the middle of the longest side . Or the glass surface could shatter been there done that.

What brand? Usually in the spec is specified if clamping is allowed on short side, long side or both. Reputable brands allow for clamping on short sides, and I have done so on thousands of panels in landscape on roof rails.

 

[cyberyacht]

Nominal amperage is only just under 10A so realistically you may only get around 7-8A. It's also quite heavy. I have 3 x100A semi flex in series from Photonic Universe that push out up to 15-16A and weigh about half that. If you have the space and the cash it's worth consideration.

 

[StitchUp]

Well, this has made a very interesting read I didn't think that fitting a 2nd solar panel would raise so many issues/questions.

I have no idea what the brand of the current panel is and I'm just assuming it's a 100w panel.

I could of course fit a 300w panel and disconnect the 100w for the time being. More investigation is definitely required

Thanks again to all.

 

[autorouter]

Nominal amperage is only just under 10A so realistically you may only get around 7-8A. It's also quite heavy. I have 3 x100A semi flex in series from Photonic Universe that push out up to 15-16A and weigh about half that. If you have the space and the cash it's worth consideration.

Are you saying the panels push out 15-16A, connected in series? Or is that the output from the solar controller, in which case what voltage will that be? I presume about 14V, so that's 210 to 224 watts. Which as you say is about 70 to 75% of the nominal power.

 

[cyberyacht]

Output from the controller. Panels never produce what they say on the packet. You'd have to be holding them facing at exactly the right angle to the sun and probably a fair bit south of Dover.

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[Raul]

Output from the controller. Panels never produce what they say on the packet. You'd have to be holding them facing at exactly the right angle to the sun and probably a fair bit south of Dover.

Yes they do with the right controller, and good design. I got several times 670-680w out of 590w panasonic panels. And that was In Kent as well, north of Dover.

 

[StitchUp]

I fitted the previous (270W) version of this Perlite panel a couple of years ago, it was the highest output I could get in the space. I used a 20A EPever mppt controller also from Bimble. I'm very happy with it as a compact low cost setup with Bluetooth monitoring. The panel is mounted with 6 plastic brackets and a tube of CT1 and it's not going anywhere.
I left the existing 100W panel and it's PWM controller alone for the reasons stated above by Autorouter - different voltage and output current characteristics.

Murrays Thanks for your comment. May I ask which panel supports you used, how many and how did you fix them to the roof?

Regards

John

 

[ianp]

Yes they do with the right controller, and good design. I got several times 670-680w out of 590w panasonic panels. And that was In Kent as well, north of Dover.

Raul
Can you suggest a few good suppliers of Panasonic panels in the UK please?

 

[Murrays]

Murrays Thanks for your comment. May I ask which panel supports you used, how many and how did you fix them to the roof?

Regards

John

Hi John,

I used standard white abs mounts. They are widely available, but I got this kit from Amazon Amazon product ASIN B016ORGABKI wanted to be sure it wasn't coming off so I went overboard and put long mounts on the front edge to prevent any unwanted lift at speed. These were also from the same Amazon seller Amazon product ASIN B07SQCLM9BI attached them to the roof with CT1 and now I understand just how good the bond is I realise that the long brackets were probably overkill.
The panel was attached to the brackets using stainless steel screws though the panel frame sides.

I found this picture, sorry it's from a distance I wasn't taking it for the panel. Anyway if you zoom in you can see the mountings.

Steve.

 

[Raul]

Raul
Can you suggest a few good suppliers of Panasonic panels in the UK please?

Sorry I don’t know any that still have them. Midd Sumer energy used to have them a while back. Panasonic pulled the plug and stopped making them. They ended their partnership with Tesla to. Unprofitable solar cells was the reason, over engineered. If you find any you will be lucky.

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[StitchUp]

Murrays

Thanks Steve, I've 'bitten the bullet' - bought the same supports and I already have several tubes of CT1 (never used the stuff before). Going to order the 295w panel tomorrow:
295W Smaller Size Perlight Black Plus Mono Percium Solar Panel - 54 Cell Smaller 1.5m Size - Great For Vans And Motorhomes

I'll feel more comfortable using electricity when fitted We're quite heavy users!

I'll add pictures when I've completed the installation.

Again, thanks for your help

 

[Murrays]

Murrays

Thanks Steve, I've 'bitten the bullet' - bought the same supports and I already have several tubes of CT1 (never used the stuff before). Going to order the 295w panel tomorrow:
295W Smaller Size Perlight Black Plus Mono Percium Solar Panel - 54 Cell Smaller 1.5m Size - Great For Vans And Motorhomes

I'll feel more comfortable using electricity when fitted We're quite heavy users!

I'll add pictures when I've completed the installation.

Again, thanks for your help

Hi John,

Good for you, as you'll see from the picture it's a nice looking panel and I've had nothing but good experience ordering from Bimble solar too.

We use around 60Ah/day on average in summer these days and have a big Lithium battery to iron out the clouds. Between the pair of 270W and 100W panels we rarely drop below 50‰ SoC between April and September. In winter the Sterling 60A B2B fills the gap.

Out of interest, which charge controller are you going for? I guess you know you need an MPPT type to make the most of the 30V panel? (Assuming you're charging a 12V battery, you'd get away with a cheaper PWM with a 24V pack)

Incidentally, you may think a 30A controller is necessary, but if you choose 20A you will miss very few Ah and save a few quid. I rarely see a horizontally mounted panel get close to the rated power in the UK.

A tip for the CT1, I used tile spacers at the edges of the mounts to put in a 5mm gap so there's plenty of flex space for the adhesive to do its job. After it cured I removed the tile spacers and applied a bit more CT1 to smooth over the small gaps the spacers left. I just use a wet finger to smooth the edges. Works a treat.

Steve.

 

[Mixyblob]

Try this panel, its nearly half the price of the one you're looking at on Amazon.
Funster Wissel has been buying and fitting these to customer's vans.

295W Smaller Size Perlight Total Black Delta Mono Percium Solar Panel. Delivery from £33 - 54 cell smaller 1.5m size - great for vans and motorhomes, MCS Approved - The Installers choice - - 30 year parts & performance warranty

www.bimblesolar.com

I fitted the very same panel to our Globecar, works very well with no issues.
Excellent company, used them for quite a few years.

 

[StitchUp]

Great stuff Not sure when the panel will arrive - soon I hope as I get excited with this sort of stuff My 100w panel will become redundant and, if there's enough room for a 2nd panel where the 100wat panel presently occupies, I might also fit a 2nd.

Thanks for the tip on using the CT1.

I presently have a Victron MPPT solar controller, the MPT 100/20 - hoping this will be suitable.

Thankyou Mixyblob for the thumbs up

 

[StitchUp]

I've now received all the CT1, the supports as suggested by Murrays above:

supports

and additional side supports

I think I'd feel a little more comfortable if, as well as using CT1 to fix the supports to the roof adding some additional stainless screws or maybe rivets.

Any comments and suggestion as to what screws/rivets I should use? When the panel arrives on 5trh May I'd like to be ready to fit and complete the installation

Thanks

John

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[Mixyblob]

I always use 2 lengths of 50x50mm aluminium angle running the length of the panel. I glue the angle to the roof with Stixall and use stainless self tappers from angle to panel so its easily removed if there’s ever a problem.
Using angle greatly increases the bonding contact area and it supports the panel along its full length.

 

[Tombola]

I've now received all the CT1, the supports as suggested by Murrays above:

supports

and additional side supports

I think I'd feel a little more comfortable if, as well as using CT1 to fix the supports to the roof adding some additional stainless screws or maybe rivets.

Any comments and suggestion as to what screws/rivets I should use? When the panel arrives on 5trh May I'd like to be ready to fit and complete the installation

Thanks

John

self drilling screws like these are easiest

TechFast Hex/Washer Self Drilling Roof Screw

Perfect for joining metal roofing sheet panels together, these TechFast roof screws are self-drilling up to 2.5mm. They have a smaller No.1 drill tip that can drill through two sheets, then engage the threads to clamp the sheets together under the head.• Used for joining metal roofing sheet...

www.toolstation.com

 

[StitchUp]

self drilling screws like these are easiest

TechFast Hex/Washer Self Drilling Roof Screw

Perfect for joining metal roofing sheet panels together, these TechFast roof screws are self-drilling up to 2.5mm. They have a smaller No.1 drill tip that can drill through two sheets, then engage the threads to clamp the sheets together under the head.• Used for joining metal roofing sheet...

www.toolstation.com

Do you use those to attach the supports to the roof or the panel to the supports? Either way, I know they're self drilling but wonder if you drill a pilot hole first?

Thanks all for the comments

 

[two]

Yes they do with the right controller, and good design. I got several times 670-680w out of 590w panasonic panels. And that was In Kent as well, north of Dover.

That seems most unusual - for a manufacturer to under-specify their product.

 

[Raul]

It’s normal. The manufacturer did not under rated the data. The standard test conditions are what’s declared and printed in the spec. So the values are at STC 20 degC. In real life, this conditions change up or down, and so the results. Worth noting that, temp coefficient for panasonic cells are the smallest in its class. That makes the cell very efficient under 20degC and little derating above 20 deg C.
Another factor to consider is the irradiation it’s not even like in the stc conditions. At stc is flashed with 1000w/m2. In real world you can be exposed to 12-1300w/m2 irradiation. If certain conditions are met, the panel will exceed the stc rating with ease.