Panel Size

[Roadie]

A question for those that have done there system. What size panel did you use? by this I'm asking the physical dimension along with the power. The reason I ask DIY Solar Power with Will Prowse on Youtube recomends the use of smaller panels of 100 Watts and not the larger ones in the 250 Volt and up range. Larger would seem to be a more efficient use of the roof space. Id like to hear from everyone as to there real life experience. Thanks

[john61ct]

Will is no expert, makes his living being a YouTuber and commissions.

My advice is to use good MPPT controllers, one per panel is ideal.

Victrons give a lot of flexibility so you can choose just about any size (amps output) to match the panels you want to maximize Watts per sq ft.

If you for example have a 250W panel, then a 75/15 would be great value for a 12V system.

A 40+ Voc rated panel will get greater efficiency from the MPPT than the old-school 12V nominal panels designed to work with PWM controllers.

The best value panels are those you find locally, ideally left over from big pro installer contracts. Specialist professional sources are ideal, if you have a high-volume brick and mortar shop within driving distance, but otherwise, shipping costs will kill the value proposition, unless you get some others to go in on a full pallet load group buy.

The ones you find from companies marketing direct to consumers from mass market outlets and online sources aren't as good.

[Drew Bru]

We went with 4 290W residential panels. 2 in front of the emergency hatch, 2 behind. They easily fit on the front half of the 11-window bus with no wasted space.

[kazetsukai]

The 305W panels in my garage are huge. I worry about a sail effect with all of them up there... One guy I know took some pretty extreme measures to mitigate after one flew (which I may do as well).

I bet big decks have the same potential problem though. I can't be worse off than this guy:



https://www.youtube.com/channel/UC3s...4nfGAtWftrPObA

[musigenesis]

Originally Posted by kazetsukai

The 305W panels in my garage are huge. I worry about a sail effect with all of them up there... One guy I know took some pretty extreme measures to mitigate after one flew (which I may do as well).

I bet big decks have the same potential problem though. I can't be worse off than this guy:
Attachment 42524


https://www.youtube.com/channel/UC3s...4nfGAtWftrPObA

I was just reading a research article from a solar advocacy organization about solar panels in the Bahamas after the recent hurricanes, and which kind of mountings survived. They basically concluded that each panel needs to be separately bolted through the roof or you're going to lose them in a storm.

[JDSquared]

Originally Posted by kazetsukai

The 305W panels in my garage are huge. I worry about a sail effect with all of them up there... One guy I know took some pretty extreme measures to mitigate after one flew (which I may do as well).

I bet big decks have the same potential problem though. I can't be worse off than this guy:
Attachment 42524


https://www.youtube.com/channel/UC3s...4nfGAtWftrPObA

Wait what's wrong with this guy? I follow them on Instagram. I haven't heard they had a problem. I love the look of a deck like that and planning the same thing.


Also I'm hoping to use big panels like you have as well, but I found a decent deal in FLA for some used 254watt

[kazetsukai]

Originally Posted by JDSquared

Wait what's wrong with this guy? I follow them on Instagram. I haven't heard they had a problem. I love the look of a deck like that and planning the same thing.

I'm saying if it works for them, my design will probably work for me as well.



They do mention wind is a problem for them, and they're considering building a wind break at the front. They put their array on hinges so they can tilt them up.

[JDSquared]

Originally Posted by kazetsukai

I'm saying if it works for them, my design will probably work for me as well.



They do mention wind is a problem for them, and they're considering building a wind break at the front. They put their array on hinges so they can tilt them up.

Oh I got ya. I've seen several comments the past year about a wind diverter so I guess that's in my design now.

[JDOnTheGo]

Four, 435 watt residential panels for me (here).

Unless you have unlimited space for mounting, I'd suggest focusing on getting panels that maximize the available space. That may mean multiple sizes.

[Roadie]

I will be fitting the panels to my 40' Crown, so I will have a good amount of real estate for panels.

[john61ct]

Can never have too much, optimize your use of available space from the beginning.

[kazetsukai]

Originally Posted by JDOnTheGo

Four, 435 watt residential panels for me (here).

I put some up yesterday. When I read your post, I noticed this:

Originally Posted by JDOnTheGo

In hindsight, I did make a boo-boo. I should have left a couple feet of space between the middle two panels for installation of the Fan-Tastic vent/fan that I have waiting. Oh well… it will now go somewhere else.

I do want to put a vent in the kitchen, and that whole area is going to be covered. I have some clearance so I might be able to get away, I wonder if it will be enough to have a vent I can crack open.

[john61ct]

Depending on curvature, might have space to place a vent under the rack out at the side edge.

Does not need to open all the way

[dzl_]

I think this is still an open ended question. I've heard some assert that smaller is better because the ratio of aluminum support to panel area is better, I've heard some assert that quality larger residential panels are built substantially stronger so they do as well or better than the smaller panels. I know people who have had good 5+ year experiences with both large and small panels.


I started a thread on the topic a while back, have a look