Downside to using residential solar panels (on top of a RTT)

M

monkeyodeath

Member
One more question...I know it's a bit of a noob one...

Should I just be trying to score the highest-wattage panel I can for the best price?

For example, I'm seeing someone selling Canadian Solar mono-crystalline 305-watt panels for $120. They are also selling Kyocera poly-crystalline 265-watt panels for $50.

Since all I really plan on powering during the day is a fridge, I'd rather keep the extra $70, which will pay for the MPPT unit. But if the higher-rated panel is going to get me more power during days with less-than-ideal sunlight, and is otherwise worth the extra expense...
 
shade

shade

Well-known member
monkeyodeath said:
One more question...I know it's a bit of a noob one...

Should I just be trying to score the highest-wattage panel I can for the best price?

For example, I'm seeing someone selling Canadian Solar mono-crystalline 305-watt panels for $120. They are also selling Kyocera poly-crystalline 265-watt panels for $50.

Since all I really plan on powering during the day is a fridge, I'd rather keep the extra $70, which will pay for the MPPT unit. But if the higher-rated panel is going to get me more power during days with less-than-ideal sunlight, and is otherwise worth the extra expense...
Click to expand...
It's really up to you, but you may find that one physical size works better than another. It's also worth considering if you decide to go with a less efficient or smaller panel, will you have space to add another panel if you decide you need more output?
 
J

john61ct

Adventurer
Yes the key is fitting as many watts as possible on a limited size roof.

So getting a size that works well, as well as maximum density watts/sqft, is more important than watts per dollar.
 
llamalander

llamalander

Well-known member
Canadian Solar makes a pretty tough panel that seems to have a consistent output and will live happily on your roof all year.
Also worth noting that the higher voltage panels start producing useable amps much sooner in the day or longer in cloudy conditions compared to 12v. arrays-
 
M

monkeyodeath

Member
Just as an update, scored a 305-watt panel that I'm working on mounting to the roof of my RTT.

One question, I'm looking at MPPT units...

I know the Victron units are popular here, but the price...$250 for one that can handle a 305-watt panel.

I'm noticing well-reviewed EPEVER units on Amazon for less than half the price.

I realize that the Victron has bluetooth and may be more sophisticated, but I'll be honest...the last thing I want to be doing when I'm out camping is staring at battery charge statistics on my phone.

If all I want is to power a fridge and keep an AGM battery happily charged, do you think something like this will work?

 
DaveInDenver

DaveInDenver

Middle Income Semi-Redneck
monkeyodeath said:
I know the Victron units are popular here, but the price...$250 for one that can handle a 305-watt panel.

I'm noticing well-reviewed EPEVER units on Amazon for less than half the price.
Click to expand...
That EPever Tracer3210AN MPPT solar controller might be a perfectly fine product or might be junk. Unless someone you know has one it's hard to tell.

Companies like Victron and Morningstar have a large installed base and are well known. But the same components and contract manufacturers are available to everyone and designing solar controllers doesn't exactly take a 100-person team at NASA. So it's completely plausible EPever makes something just as good with just as many features for half the price.

There's certainly a price premium buying a tested model from a known brand that a lot of people have experience with. What that gets you is expected operation, customer service, a distribution network and a warranty.

For the price saving it might be a worthwhile gamble, hard to say. But you probably should approach it as a disposable item if you happen to have an issue.
 
Last edited:
J

john61ct

Adventurer
But using a US-based credit card with good buyer protection, certainly worth a try, pick up three, sell one at a profit still have a spare
 
M

monkeyodeath

Member
I was looking into that Victron controller, but according to their website, I need the 30-amp model. Is this the case? I'm having a bit of trouble figuring out exactly how much MPPT I need for my panel. (specs below)

00j0j_1Mr3TL4MdK0_1200x900.jpg
 
Alloy

Alloy

Well-known member
john61ct said:
But using a US-based credit card with good buyer protection, certainly worth a try, pick up three, sell one at a profit still have a spare
Click to expand...

There's no Victron model number.

and

CONTACT INFO
Email: zzyujie36@gmail.com
Phone: +86 15196756430
Recipient: Zheng Yujie
Room 1704, Building B, 108 Ruiping Road,
Xuhui District, Shanghai City, 200030 China
 
J

john61ct

Adventurer
No, only need to be careful about the voltage.

The amps rating is a maximum **output**, at the bank charging voltage. Assuming a nominal 12V system? Wattage output doubles with a 24V bank.

So even the 75/15 would be fine for that panel, nor harm done, just a bit of bank input sacrificed in very rare **peak** conditions only.

If you aren't using a tilting frame and LFP, not significant enough to pay much more.

Certainly not at 20A (* 14+ charging volts), you won't actually realize that for any length of time even in peak conditions.

Best of times you might average 100Ah per day from that panel, that really is the key metric, and even if the Victron was 5x the price getting the 5-10% extra overall **average** charging energy would be worth it.

Not to mention user-custom profile tweaking to get maximum longevity out of your banks, which you will be replacing many times during your SC lifespan.
 
You must log in or register to reply here.

Forum statistics

Threads
189,400
Messages
2,916,426
Members
232,261
Latest member
ilciclista

Members online

Total: 2,709 (members: 29, guests: 2,680)
Top