Make SURE the panels carry a marine warranty IN WRITING and that you'll have a company that is standing behind you a few years down the road. I've seen a few eBay panels "frosting" in under a year..
Kyocera panels are more expensive but also VERY reliable in the marine environment. If you want a cheap US based company, of which I have no psychical experience with, you could try Sunelec or
UL Solar.
Be sure with any of these companies to get a "marine warranty" in writing.While those eBay panels may survive a for a while I would be certain they carry a warranty for the marine environment. Very few panels are covered for marine use.
Also I have seen "Chinese" eBay MPPT's and they are NOT worth the cardboard box they ship in and some are not even MPPT at all and behave more like a cheap shunting controller.. PLEASE be careful with solar/eBay I've seen to many of my customers get scammed on solar products. Most people are too naive about solar to know the difference between good and bad so the eBay scammers can get away with it.
There are plenty of legit low margin solar re-sellers who do sell reliable, well built products.
I have seen to many of my customers scammed buying eBay solar stuff but they don't know enough about how it should operate to even challenge the eBay seller, thus the seller still has a good rating. Solar is very, very difficult to claim "performance" issues with because the sun, batteries and system are far to complex and leave way to many variables to for the average DIY to even begin to comprehend. Thus, there are a lot of snake oil solar sellers who CAN get away with selling controllers or panels that are are not MPPT, or do not meet the performance spec despite claims of such, or PWM's that are not PWM at all and rather shunting controllers...
While that price is inexpensive $275.00 dollars is not a gamble I would be making on no-name panels or a no-name eBay controller. Just my $0.02.
If you stick with controllers made by companies Morningstar, Blue Sky, Outback or Genasun you'll be doing well.
I use Arizona Wind Sun, Wholesale Solar, eMarine and a couple of others.
I have added a video of a "cheap" controller and it illustrates well why the performance of the controller is so critical...
Specifics:
375 Ah bank
80W Shell Monocrystalline Panel
FlexCharge PV-7 Shunting Controller
On voltage = 13.6V (specs say 13.5 - 13.8V)
Off Voltage = 14.4V
Bank had been at 100% SOC from shore charger. Discharged bank by 20 Ah's and left the Flex Charge to charge the bank for 4 days. At day 5 bank still not full and Ah's not yet replaced. It had been blue sky & full sun all week. Panel can put out 4.4A - 4.5A +/- in good sun or about 3-4 hours per day in Maine.
What happens with sailboats is that there is no load when left on a mooring so shunting controllers build the battery to absorption voltage then begin turning on and off to regulate the voltage. This boat has a stand by draw of 0.1A, which is a combination of the ACR relay, electronic bilge switch, stereo memory & charge controller.
The problem with On/Off controllers is that good deep cycle, gel or AGM batteries will hold a surface charge and when the charge controller turns on at higher states of charge the voltage rapidly comes up to absorption, if there is no load on the batteries. This can happen despite many Ah's still needing to flow into the bank.
Once the batteries hit absorption voltage the controller then turns off. Again, with good batteries, the time it takes for the surface charge to dissipate and fall back to the OFF voltage can take a loooong time. In colder temps a VERY long time.
This particular Flex Charge is better than many shunting controllers in that the ON voltage is approx 13.6V +/-. Some cheaper controllers, like the Sunforce units, are ON at 12.9 volts and it can take 20 minutes to four hours or more for the bank to fall that low with no loads on them. I watched an AGM bank sit at 13.0V - 13.1V for close to an hour waiting for the crappy Sunforce controller to turn back on at 12.9 volts and this was at 80F.. I have seen AGM's hold 13.0V for 4+ days in colder temps.
In contrast a Genasun GV-10MPPT controller applies a constant voltage to the bank until 100% full and the current flows as the bank will accept it. Once full it does pulse the charge but the OFF time is about 1 second. It does a true float voltage and does not rely on an ON/OFF process to prevent over charging of the batteries. This allows the bank to be re-charged significantly faster than a shunting controller. The difference in re-charge times from 80% state of charge to 100% state of charge is not measured in hours or minutes but rather DAYS..
I have spent considerable time comparing shunting controllers and cheap PWM's to MPPT's and the real benefit, with good MPPT, is not so much in the voltage to amperage conversion but the fact that they supply a constant voltage and do not go into an ON/OFF scenario when the banks get near full charge.
Here's a video showing the current switching ON/OFF based on the specifics above.
If you note the time it spends ON, about 5 seconds, and OFF, about 53 seconds, it does not take a genius to figure out that with only 5 +/- good hours of charging per day how many days it will take to completely recharge the bank to 100%. And this is one of the BEST shunting controllers you can buy. This bank still had 12 Ah's to be replenished. With 5 second pulses how long will that take??
Buy solar carefully and don't buy solely on price....Reputation, quality, real world performance and service after the sale should all be considered.
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