Solar panel for sailing boat

[Olive]

Hi everybody,

i m writing from Marmaris Aegean sea coast.
i want to install solar panels on the stainless steel arch of my sailing boat.
the temperature (which effects the efficiency) is always high in the summer time and also the shade of the boom and mast will be on the panels most of the time.

there is 2 alternatives
1- Using 80 watt X 3 panels (wurth - cis) (Vmpp 35 v - Voc 44 v - isc 2,5 a - Vsmax 1000 v)
2- Using 135 watt X 2 panels (solar fabrik - polycrystalline) (Vmpp 17,94 v - Voc 21,86 v - isc 8,08 a - Vsmax 1000 v)

i will connect all the panels parallel.
i have 100/50 Victron MPPT and 2 X 210 amp 12 v dc gel battery.

if i will use 1st alternative the calculation will be as follows 80 x 3 =240 watt 240 /35= 6,85 amp before MPPT 35 /14,4 v dc(for charging gel battery)= 2,43
6,85 amp X 2,43 = 16,64 amp

2.nd alternative 2 X 135 = 270 watt 270 / 17,94 =15,05 amp before MPPT 17,94 / 14,4 vdc = 1,24
15,05 amp X 1,24 =18,66 amp

if i will install first second choice, then i must use thicker wire from panels to MPPT controller.
Also, in the first one i will use 15 amp 55 volt dc circuit breaker between panels and controller. in the second one it will be 25 amp 30 v dc.

The higher voltage panels are cis panels and because of the high voltage they will effect less than other polycrystalline. (if thats true)


Please inform if am I wrong.
Thanks ...

[Mike90250]

Avoid the CIS panels, their power output drops after a few years, and the panels are highly toxic.
And shade is a problem. Shade on a panel shuts it down. With panels in parallel, you still have a lot of shade issue, and shaded panels don't produce much

I would use the 2, 135W panels in parallel and a simple PWM controller. not knowing your loads, I don't know if the panels will be able to keep the battery full.
Be sure your battery is AGM (absorbent glass mat) and not GEL (jelly electrolyte) GEL cannot be charged quickly, AGM can. Be sure they are labeled DEEP CYCLE

[Olive]

Thanks for your quick reply Mike90250.
Your suggestion was very helpfull for me. Especially for the cis panels.
The highest loads are the isotherm ASU refrigerator and the Waeco cfx deep cooler. Both 12 vdc. So the total load per day is reaching sometimes 100 amp.
In the summer time most of our friends are loading 60-70 amp to their batteries with 200 watt 12 v panels in one sunny day. Thats why we prefer 3 X 100 panels. We can also choose 150 X 2 panels, but because of the shade risk we prefer 3 X 100 watt.
We are able to charge the batteries with a small Honda generator or just with the alternator on the engine.
Also, what is your suggestion about the fuses and circuit breakers. Today one of my friend insisted me to use 10 amp fuse for every panel before parallel connection for protecting each panel separately. Also he suggested to use 75 amp fuse between MPPT controller and batteries.
For the AGM and gel batteries, we will take your suggestion into consideration.
Thanks...

[Mike90250]

I won't comment on fuses, because I don't have a schematic. Too hard to describe one thing, and the other person thinks of another,
Panels have a fuse spec on them for parallel usage, that is what you use,
The high voltage panels, wired with a PWM controller to a battery, will only deliver about 35% of their nameplate power into the batteries.

[Sunking]

[QUOTE=Olive;n311236]So the total load per day is reaching sometimes 100 amp.
In the summer time most of our friends are loading 60-70 amp to their batteries with 200 watt 12 v panels in one sunny day. [\QUOTE]

Your terms are incorrect. I think you mean Amp Hours. Any to the point. Assuming you could place the panels pointed due Solar South, and the correct tilt angle, and full sun exposure from Sun Rise to Sun Set with no Shade issues, and a very long 5 Sun Hour Day, a 300 watt panel on a 12 volt battery assuming you use a MPPT controller will generate 125 Amp Hours. Problem is you cannot meet those conditions on a boat.