roof mounted solar panels - which ones to get?

[rlynch356]

I am currently running 2 100w cheapo semi flexible panels i had for my camp trailer on the roof of my truck. i am pretty sure they have been damaged due to being stepped on a few times...and the best they put out in full sun at about noon is 107 watts together when wired in parallel.
so its time to get a rigid panel for the dedicated roof mounting to my rack on the 110. Ideally i want to get a consistent 150+ Watts out of them in full sun.

i was considering a couple of options, a Renogy 160w panel or a pair of 100w panels...
can i get away with the 160w?

my setup is 10g cable to a Victron 100/20 solar controller. Then 10g cable to the battery (PC1500 odyssey) primarily used for a fridge, but also supported by a NL split charger. The nice thing there is at 13.1v the NL connects the batteries and the solar system can charge the starting battery as well.

looking for advice and options.

thanks

 

[dreadlocks]

what kinda space you working with? 200W is better than 160W.. its very hard to get peak output, especially with a fixed panel.. so a 160W will rarely output 150W+ and 200-240W would far more often.. put as much wattage as you can fit up there for fixed situations usually, unless you just have a ton of roof space and a tiny battery bank.

Flexible ones take damage just sitting in sun, rigid ones will last far far longer.

 

[rlynch356]

right now the panels will dictate the roof layout which is a full rack on a defender 110, so 4'x10' ish i don't link heavy loads on the roof, so no tent or other such stuff in the way.

thats kinda what i was thinking 2x100w rigid panels, would be better than a single. they will be bolted in place flat on the rack.

 

[dreadlocks]

look at house panels, you can get single 200w+ ones that will fit up there.. they output higher voltage (good) and would weigh less and take up less space (they usually more efficient)

 

[rlynch356]

humm.. interesting but i believe the MPPT 100/20 has a max of 24vdc if i am reading the spec right

https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-75-10,-75-15,-100-15,-100-20,-100-20_48V-EN.pdf

-vs- say this house panel which is a max of 35.5vdc

Canadian Solar CS6K-300MS Black Mono Solar Panel

1930009

300W

9.24A

32.5VDC

65 × 39.1 × 1.38 in 40.1 lbs

a house panel would definitely fit, and is cheaper as well..

am i reading that right?

 

[dwh]

The Victron naming scheme is volts|amps, so a 100|20 can accept up to 100v on the solar and output up to 20a to the battery.

I think the battery side is 12v or 24v auto-detected.

I use a 100|30 with a 300w 36v panel.

 

[dreadlocks]

I have a 100/30 SmartSolar w/Panasonic HIT 325w that outputs nearly 70v on the roof of my setup..

Now you only have a 70AH AGM, so will your battery ever take a full 300W charge IRL? Not likely, if it does it wont be for very long.. however oversizing solar would provide you with far better output in less than ideal lighting conditions.. this last weekend it was overcast one day and my panel still was outputting 100W of power, vs a 200W panel @ 33% is only 66W of power.. but my panel is super good in low lighting conditions so a pair of 12v 100W panels might of only been putting out like 30-40W of power IRL..
Oversized solar would also be good if you have any ambitions to move to a LFP bank in future, as the'll gladly soak up a 300W panel at full output all day long (not really tho, it'll be charged up in a few hours)
Oh and being a bit oversized also would let it power your fans/fridge directly while also providing the battery with whatever charge current it needs at the time and not sacrificing charge time because its hot and you need a 3A fan running and siphoning power off the charge.. as long as sun's shining well on it you'll have an excess of power so running radios to play music or tossing a bunch of beer in the fridge to cool down wont really touch the battery or impede its charge rate.

 

[sancap]

I have 2 100 watt Zamp solar panels I got from Amsolar.com. Yesterday I saw 197 watts coming from them running a 2000 watt inverter with a small DC exhaust fan, 12 volt compressor fridge and a 110 volt floor fan. I am running all of this off of 2 deep cycle Interstate 4D batteries. I am using a Victron MPPT 75/15 smart solar controller.

 

[rlynch356]

eventually i was going to go with a larger lithium battery for these loads. the current setup is dictated by the need to connect the 2 batteries together on occasion. once i go dedicated house battery i'll use a dc2dc system for it and the solar. so it sounds like 200 watts or go with the 300w house solar panel and that will be overkill for my current battery and enough for my future plans. i'm going to measure and see what fits best, but having good low light performance would be very nice as well.

 

[dreadlocks]

I dont think anyone's ever regretted putting too much solar on, but plenty of people have gone the other way.. its one thing to fix a panel to one location on this planet, its another to fix it to a vehicle and drive it all around where each location's lighting conditions vary so much from site to site.. all the little things that chip away at output really become apparent in these situations.

 

[the406]

Can anyone weigh in on the overall quality/durability/performance of Zamp Portable Solar Panels? Looking to get a 45 or 90w for our 16' RV. It is pre-wired, and just looking to have it for when we need to recharge for longer duration outings.

 

[dreadlocks]

IMHO, Zamp is the Yeti of solar.. they slap their name on something cheap outta china and now its stupid expensive for some reason.. but if you need that Zamp street cred, then I guess its yer money.

FWIW, My 325W Panasonic HIT (considered one of the best panels on market), cost over a hundred dollars less than a 90W zamp portable panel..

 

[the406]

IMHO, Zamp is the Yeti of solar.. they slap their name on something cheap outta china and now its stupid expensive for some reason.. but if you need that Zamp street cred, then I guess its yer money.

FWIW, My 325W Panasonic HIT (considered one of the best panels on market), cost over a hundred dollars less than a 90W zamp portable panel..

That is good feedback, thank you. I'm really looking for the best quality for my money for a consistent, workhorse solar panel; name brand makes zero difference to me. Function wins in my book, and I am more or less a noob when it comes to solar panels.

 

[dreadlocks]

What are you wanting to accomplish? Indefinite boondocking off the grid? Just keeping batteries full when parked in storage? Making it through a weekend? What kinda battery bank do you have current, what kinda battery bank are you planning for in the future? Do you have any idea your current power requirements (average AH per day)?

Generically, 200W of solar per 100AH of Lead Battery is about the sweet spot in price vs performance.. with less you'll likely feel underwhelmed with performance.. more than that the returns are diminishing unless your planning on expansion, or poor lighting conditions.

 

[sancap]

IMHO, Zamp is the Yeti of solar.. they slap their name on something cheap outta china and now its stupid expensive for some reason.. but if you need that Zamp street cred, then I guess its yer money.

FWIW, My 325W Panasonic HIT (considered one of the best panels on market), cost over a hundred dollars less than a 90W zamp portable panel..

Zamp's webpage and media sure make it sound like they manufacture their solar panels here in the states.