Solar panel question - partial shading

[svsonora]

I previously stated I had polycrystallaine panels when I actually have amorphous silicon panels. Not the fancy thin ones. Harbor freight 100w kit. Got them for real cheap on sale. They actually get quite good reviews.

Currently all 4 25w panels are wired in parallel mounted onto a bimini frame, under the boom. There is always going to be shade on some parts of the panel array. My cheap watt meter shoes 1-2 amps. The panels are all hooked up to a single MPPT charger, that is wired directly into my house bank.

I am wondering if there is any way to increase the efficiency of my setup. I don't want to look for another mounting location. If I go to mono, I can probably fit 300watts on the same location, but I want to try to make my current setup work.

If I wired 2 stbd panels in parallel, separate from 2 port panels, also wired in parallel, and hooked them up to two separate MPPT chargers, will that make any noticeable difference? My hunch is no.

I'm thinking the only real solution is to add wattage, unless I want to get a new mounting solution which will involve something more hardcore like a new arch or something.

Thanks in advance.

Any other suggestions?

[Boatsie]

I don't know if this information useful.
I assume you have partial shade on 3 panels therefore wiring 2*2 instead of 1*4 wouldn't be beneficial.

At home I use 32 panels. 4 lots of 8 series.
With 2 inputs I have 2 parallel connections of 8 in series to each input.
During winter, the low angle partially shades 2 panels .. The approximately half shade on 2 panels in 1 of the 8 series array reduces the voltage of that whole system. Eg 16 panels. Although the other series of 8 is in full sun, the input is 10% of the other parallel connection receiving full sun on 16 panels.
If you could get full sun on two panels on a separate system you would remove the systems ability to drag their potential down. IMHO I would have 2 inputs(chargers) such that port and starboard are isolated from each other.. Assuming you usually get full sun on either side at most times.
Nathan

[Boatsie]

Difficulty with boats and solar panels are that solar panels are probably rated directly looking at sun. Eg a shadow the size of a panel.
Boats pitch and roll. Hence I think 50% of 50% seems a fair take.
I'm guessing mppt has 2 inputs.
Interested in reading what others achieve too

[svsonora]

Thanks. More exact numbers: 1.5-1.8 amps @ 18-19 volts. I guess this isn't too bad. With the same wattage, at 14 volts (alternator charging current) it would be 2.44amps. That's about 50% efficiency which is greater than I expected, but is the higher voltage, lower amp current charging the batteries the same?

[Pete7]

When you took the measurements were the batteries full? because 1.5A from a 100w panel isn't great. Was this in full sun mid day or cloudy rainy early or late. You have nothing to loose trying 2 x 2 through the MPPT, its onlt a bit of wire and half an hour of your time.

What is the MPPT, can you interrogate it to see how much it has been charging? You could also try putting a load on the full batteries to see if that helps raise the charging current. Finally is the MPPT set at the default settings, can these be changed to match the batteries? so 14.8v for FLA with temperature compensation?

That should give you some ideas to play with today.

Pete

[svsonora]

That was what I was getting when I was underway with AP on. When battery is topped off, I get below 1A. I have a very basic MPPT. The device I am using is 'wattsup' https://www.amazon.com/RC-Electronic.../dp/B001B6N2WK Hooked up after the panels but before the MPPT.

I did order a victron battery moniter so I don't question my readings anymore. I'll update after I install that.

[Stu Jackson]

Originally Posted by svsonora

>>>>>>>>>>>>>>>>>>
When battery is topped off, I get below 1A.>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>

Of course you do. It's called battery acceptance. The higher the SOC the less amps a bank can take. Unless you knew that already...

[MJH]

Originally Posted by svsonora

I previously stated I had polycrystallaine panels when I actually have amorphous silicon panels. Not the fancy thin ones. Harbor freight 100w kit. Got them for real cheap on sale. They actually get quite good reviews.

Currently all 4 25w panels are wired in parallel mounted onto a bimini frame, under the boom. There is always going to be shade on some parts of the panel array. My cheap watt meter shoes 1-2 amps. The panels are all hooked up to a single MPPT charger, that is wired directly into my house bank.

I am wondering if there is any way to increase the efficiency of my setup. I don't want to look for another mounting location. If I go to mono, I can probably fit 300watts on the same location, but I want to try to make my current setup work.

If I wired 2 stbd panels in parallel, separate from 2 port panels, also wired in parallel, and hooked them up to two separate MPPT chargers, will that make any noticeable difference? My hunch is no.

I'm thinking the only real solution is to add wattage, unless I want to get a new mounting solution which will involve something more hardcore like a new arch or something.

Thanks in advance.

Any other suggestions?

You can't go wrong by adding more solar. When researching solar for my boat I corresponded with a couple guys in the Pacific that said to get as close to 600W as you can. You are always going to have issues that will affect solar panels on a boat so max out the area you have available and don't worry about it. I ended up with 4 x 140W (560W) and don't think twice about it. Each pair is connected to its own controller and then to one of the 8D Gel batteries (these are the biggest panels I could get above my dogger and new stern arch. On my roundtrip to Hawaii I never had to run the diesel to charge the batteries although I did run it due to lack of wind...batteries never got below 78% and were fully charged by mid-afternoon.

Good Luck.

~ ~ _/) ~ ~ MJH