diy solar

diy solar

Trend toward bigger panels

svetz

svetz

Works in theory! Practice? That's something else
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Is Bigger Really Better, or is it just cheaper?​


$/W​
Watts​
size i(in²)​
Wind (Pa)​
W/in²​
Weight (lb)​
0.61​
540​
4000​
5400​
0.135​
73.6​
0.79​
360​
2797​
5400​
0.129​
44.9​
1.18​
200​
1573​
5400​
0.127​
26.5​
2.85​
200​
2336​
​
0.086​
6.39​
1.70​
200​
1858​
0.107​
10.8​

Pulled some numbers on a few random panels while pondering what the best size might be. A smaller size makes it easier to fit roof geometries and less wind loading when carrying up to the roof. Less mass, so easier for a single person to handle. But smaller also means more wiring and microinverters if you use them (if using microinverters, it would also be easy to use any size panel to meet any geometry).

But, the bigger panels do seem to have a higher W/in² and they are cheaper per watt. Also looked at two of the flexible panels, taping them to the roof is a lot less expensive and less complicated than rails, doesn't increase weight like ballistic mounts, shipping is a fraction of the cost, and no roof penetrations. But also no air cooling underneath and I'm not sure VHB tape will last 30 years.

What are the pros and cons regarding physical size that come to you?
 
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Hmmm ... recently went w/ Renogy (8' x 4') 550w panels, as just 4 of them (2s2p) max out my midnite solar classic 150 *and* they are the basis of a full (south-facing) carport, right next to the utility shed holding all the solar gear.

These replace some 265w panels (5' x 3') that cantilevered out, but didn't really form a carport.

I dislike roof-mount (penetrations, height) and ground-mount (distance, loss of ground space), and got lucky that the carport need is also south-facing.
 
Considering how the PV portion itself is made and not having looked into this price issue much at all, i would venture a wild guess that it basically comes down to smaller panels = more framing cost, diode cost, PV wire and connector cost, per watt when averaged.

For a DIY install i think it's absolutely valid to make 'difficulty of installing by myself' a major design factor.
 
Cost , is always my main deciding factor.
I'm planning a ground mount, strictly for winter production. I'll be looking for cheap used bi-facial panels. Size won't matter, because I can build the rack for whatever panels I choose.
 
The issue with the larger ones is they become more difficult to provide the 5400 Pa load rating if that matter to you. I looked at those 540W Vikram modules for instance since I also need another winter array and you have to fasten them down in 8 separate locations (8 bolts) in order to get the 5400 Pa rating. If you are having to put that much bracing behind a bifacial it starts to not make sense. Plus I think they would simply be much more at risk of flexing in the middle. I have 8 Kyocera KD315GX panels on a mount and those are much smaller then what you see on market today and yet they have a separate aluminum frame brace going across the back center for the increased support.
 
Watts per lb could be an interesting metric.

Not that it applies to many but smaller panels, as in 100w, can be better for solar water pumping applications. For solar direct (no batteries or inverter) it's often more about getting the Vmp of the solar array matched to the pump can often than it is total watts.

We recently got a great deal on some 535w Bi-Facials locally, $.42/watt and no shipping so we installed around 30kW of them in various off grid and grid tie projects. They were a booger to get on the roof but for a ground mount they are just fine. Matching up thier voltage for battery charging application was problematic with standard 150v charge controllers and even 250 Voc. 50 Voc limits you to 2 series on 150V SCC which can quickly get clumsy but the flexibility of something like a Victron 450/100 and it's 2 MPPT's was very nice.
 
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For me it was looks, people can see my roof so I chose black panels. Cost and conversion efficiency were second, I did not worry about size as I had a helping hand lifting them onto the roof, I would not even carry a small one alone as a wind gust might make me lose control of the panel, break it and damage the roof to boot.
 
Vigo said:
...For a DIY install i think it's absolutely valid to make 'difficulty of installing by myself' a major design factor....
Click to expand...
When I was looking at the flexible panels one of the ads was a tiny bit offensive (Chinese translations can be hilarious), it was something like "so light an old person can do it". The truth can hurt... ; -)
 
This thread gave me an idea. You know those metal carports that are marketed everywhere for little cost? I wonder if one could be designed to be made from solar panels (assembled in just a few hours by people of dubious US citizenship) with the leads from the panels going to a combiner box and left to the homeowner to connect from there?

ETA: You could call them Solarports. :)
 
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Personally, I wasn't going to go up to my 2 story roof with a giant set of panels by myself, and watching the installers do it for me made me really happy I didn't. Those 400W REC panels are pretty big to be handing that far up.

Now if I was doing a ground mount or doing something on a 1 story roof equivalent (shed, car port, etc) then I'd DIY that, with the help of a friend if the panels are big enough.
 
Mattb4 said:
This thread gave me an idea. You know those metal carports that are marketed everywhere for little cost? I wonder if one could be designed to be made from solar panels (assembled in just a few hours by people of dubious US citizenship) with the leads from the panels going to a combiner box and left to the homeowner to connect from there?
Click to expand...
My plan all along has been to build a 'solar carport' for my panels, which are.. still laying on the ground after almost a year. :oops:

Its the damn kids man. Don't make all the plans in the world, and have 2 kids, in the same general time frame. It is a rude awakening. ?
 
Mattb4 said:
This thread gave me an idea. You know those metal carports that are marketed everywhere for little cost?
Click to expand...
You could plug the EV right in, I like it!
SparkyJJO said:
... Those 400W REC panels are pretty big to be handing that far up....
Click to expand...
and they're like sails if you get a sudden wind gust.

Some of those solar fatalities are from falling off the roof. The image is
a link to more details.		1677858946084.png
 
Vigo said:
...Its the damn kids man. Don't make all the plans in the world, and have 2 kids, ...
Click to expand...
When they're old enough to turn a wrench it'll become a father/kid project they'll remember fondly for the rest of their lives.
You, your hair will turn grey. Or fall out. Or both. ; -)
 
Mattb4 said:
This thread gave me an idea. You know those metal carports that are marketed everywhere for little cost? I wonder if one could be designed to be made from solar panels (assembled in just a few hours by people of dubious US citizenship) with the leads from the panels going to a combiner box and left to the homeowner to connect from there?
Click to expand...
Right! Almost everyone can use a carport. The network for distribution and installers is already in place.

We are looking at do a project where we are just buying the legs and using solar panels for the roof. I've called a few of those manufacturers and they are typically engineered to 35 PSF which leave plenty of room for panels.
 
Vigo said:
Its the damn kids man. Don't make all the plans in the world, and have 2 kids, in the same general time frame. It is a rude awakening. ?
Click to expand...

Dude, tell me about it. I got 3 now. Projects? What projects?! Sure I got 'em, and none of 'em are done!
 
svetz said:
A smaller size makes it easier to fit roof geometries
Click to expand...

In my case, it was more effective to go with two larger panels on my RV roof. Three smaller panels (with a higher aggregate wattage) would not fit. I did use six Z brackets on each panel, so there was a bit more effort and coordination involved with so many brackets.
 
I was looking at toledo solar as their panels are only 2x4 and I think they look fabulous on a roof. However, they expect 90V inverters and I could not find any micro-inverter that would do that kind of voltage (I think only enphase has one model).

I ended up purchasing CS1Y-385MS Pallet and that is about 0.12/sq in. I paid about $0.48/w by the pallet before shipping and taxes.

We have to take extra care in moving them to roof of a single story home and only time will tell how they perform.
 
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