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

 

[Itsmcb]

Anyone using CT1 should treat themselves to an (aerosol) tin of 'Multisolve'. It's the specific pre-cleaner and solvent for CT1. You'll be glad you did if you get any on your hands or clothes. It also makes cleaning off and smoothing MUCH easier. Howdens usually have it on the shelf.

 

[Raul]

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

Here is couple of shots of that performance. Victron 100/50, LiFePo4 400ah, and inverter feeding induction hob at the time. Panels are old panasonic N295w compact

I could had more with a bigger controller, the amps from the panel are throttled back by the mppt, as I reach controller limit.

 

[Tombola]

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

you can use it for both., I drilled and screwed my previous ones, but I didnt screw this time on my roof, just glued.
no need for pilot holes

 

[Murrays]

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

Hi John,
There really should be no need to drill into your roof, the adhesive is great stuff and should do the job perfectly well by itself. If you're in doubt, glue the mounts and try to pull them off a couple of days later...
I just used standard 20mm stainless self tapping screws into the panel frame to hold the panel to the bracket, with a pilot hole as you suggest. The self drilling screw suggested may be a good option, but you'd probably want to drill the holes in the ABS mounts to get them in the right place anyway. I found it easy just to drill the pilot holes through the plastic mount and panel side at the same time.
Steve.

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[Murrays]

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

The Victron MPPT charge controller should be ideal for the job, assuming you're charging a 12V battery bank. 20A is enough, you'll rarely be power limited with a flat roof installation.

By the way if you still have the 100W panel on the roof, it seems a shame not to use it, have you thought about just using a cheap 10A PWM controller to connect that in parallel? That's what I did anyway. I also added a manual switch to the output of that PWM controller so I could connect it to either the vehicle or hab battery, that way, when we're touring it helps charge the hab battery and when we're not it keeps the vehicle battery topped up. You can buy charge controllers that have 2 battery outputs, but they're more expensive and typically charge the vehicle only when the hab battery is full, which isn't what you want with a Lithium pack when not in use. The switch solution is a nice simple and cheap method that works well for me.

Steve.

 

[StitchUp]

Thanks Steve,

Yes, using 12v (2x120ah leisure batteries) would like LiPo but to expensive just now.

I am considering keeping the current 100w solar panel, TBH I've not really any info on the current solar, it could be an 80w - all I know is, it's working

There's been a delay in supply of the 295w panel so won't be installed in time for the Newbury Motorhome show - I'll post pictures of my success

 

[StitchUp]

Anyone using CT1 should treat themselves to an (aerosol) tin of 'Multisolve'. It's the specific pre-cleaner and solvent for CT1. You'll be glad you did if you get any on your hands or clothes. It also makes cleaning off and smoothing MUCH easier. Howdens usually have it on the shelf.

Ordered, thanks for the tip

 

[StitchUp]

Spent the day fitting the 295w panel and a 2nd Victron controller, Getting 34v off the panel.

Quick question I now have 2 outputs (one from each Victron both destined to connect to the battery) Can I just connect these outputs together at the Victron end and run a single cable down to the battery - or do I need to put a diode in each of the lines from the Victrons?

This is just the new panel showing 31.60v (have seen 34) but only 0.5A - Is that correct? I guess I expected to see greater current. Batteries are fully charged.

Cheers

John

 

[autorouter]

This is just the new panel showing 31.60v (have seen 34) but only 0.5A - Is that correct? I guess I expected to see greater current. Batteries are fully charged.

The solar arrays you see on house roofs push out full power all the time, any excess more than the house uses is diverted into the electricity grid.

In a motorhome there's nowhere for the power to go if the batteries are fully charged, so the controller dials back the power and doesn't generate it, so is effectively wasted.

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[autorouter]

Can I just connect these outputs together at the Victron end and run a single cable down to the battery - or do I need to put a diode in each of the lines from the Victrons?

There's already a diode in each of the Victrons, so they can be paralleled together.

 

[StitchUp]

autorouter
Thanks very much for the help