Best Solar Panels For The Buck

[prroots]

The installation is complete except for delivery of the special Radox connectors (ref: http://www.alhof.com/cataloghi/cat_p011_f2003.pdf) that the panels use. In the meantime, I have jury-rigged a connection for testing. Here are a couple pics:

[prroots]

Here's a simple explanation of how blocking and bypass diodes function in conjunction with solar panels:

Blocking and By-Pass Diodes Used in Solar Panels

According to the following spec for my two model PW2050-210 panels, each panel has 4 bypass diodes:

http://www.photowatt.com/documents/p.../PW2050_EN.pdf

I assume each bypass diode covers 1/4 of the cells. Does that sound right? If I understand things correctly, one string could be shaded and I would still get 75% of the power out of that panel.

I am still trying to figure out whether to wire them in series or parallel. I've pretty much decided to test them both ways under similar levels of irradiance.
Pete

[oldjags]

I don't know anything about solar panels - but in general, wiring them in series will double the voltage they put out and the current will stay the same. Wiring them in parallel will double the current and the voltage will stay the same. If your controller doesn't care what voltage it's getting, it won't matter much, as either configuration puts out the same amount of energy.

[prroots]

Originally Posted by oldjags

I don't know anything about solar panels - but in general, wiring them in series will double the voltage they put out and the current will stay the same. Wiring them in parallel will double the current and the voltage will stay the same. If your controller doesn't care what voltage it's getting, it won't matter much, as either configuration puts out the same amount of energy.

Thanks. What you say is very true except that the effect of shading in parallel vs serial could make a big difference. That's the issue
Pete

[Cotemar]

Wire them in series if they are side by side.
Wire in parallel if each panel is located in different locations on the boat.
MPPT controller does what’s best for either wiring scenario.

[forsailbyowner]

Ok here comes the cheapskate again, I have two 180 watt panels purchase from sunelec.com for around $500 delivered, I also have 4, 65 watt panels that I got for building someone a bimini. I have a stainless 1" tube running across the center top of my bimini and dodger. Using jaw slides from my bimini tool kit the panels are mounted to the bar so they can be tilted up, one at a time with the big 180s and two of the 65s to face the sun, I do this at anchor only with the boom swung to a shroud, I also have two 30 watt stainless backed flat panels mounted on the deck.theres also a modified 400 watt airx in system. All the wiring is done with discarded shore power cords rescued from dumpsters, Pos neg and chassis ground run to the boats bonding system. all panels have a diode inline of pos.No charge controller between charge and the 8 golf cart battery bank, just breakers. I liveaboard full time and keep an eye on the battery charge, sometimes I get up and tilt the panels to the sun. 'Sometimes I turn the fridge up to max and kill some panels at the breaker to cool batteries down. Sometimes after a cloudy windless stretch I let them boil for a while to equalize. My last battery bank lasted 5 years at which time they still did the job but the cold charged voltage was down to around 12.4 volts. Im able to sail continuously without draining batteries running everything necessary, I also run my 400 watt sewing machine without a thought through the workweek. Many have much more invested than I do, whole system cost around a grand (not including trades and dumpster diving)but it works fine for me.

[Cotemar]

prroots,

Do your panels lay flat also or are they always tilled?
Why not use standard waterproof MC4 connectors?

http://www.cruisersforum.com/forums/...tml#post880732

[jdoe71]

Originally Posted by prroots

The installation is complete except for delivery of the special Radox connectors (ref: http://www.alhof.com/cataloghi/cat_p011_f2003.pdf) that the panels use. In the meantime, I have jury-rigged a connection for testing. Here are a couple pics:

Man, I'd be concerned about a good wind taking that whole structure right off the boat. Are the ends on your SS rods through bolted and not just held on by those little set screws? Hope your panel frames are bloody stout. I have similar size panels and in a good breeze there is a pile of load on them. Mine are mounted much lower and more securely than yours, I gladly gave up a few amps to keep them on the boat. Good luck.

[forsailbyowner]

Originally Posted by jdoe71

Man, I'd be concerned about a good wind taking that whole structure right off the boat. Are the ends on your SS rods through bolted and not just held on by those little set screws? Hope your panel frames are bloody stout. I have similar size panels and in a good breeze there is a pile of load on them. Mine are mounted much lower and more securely than yours, I gladly gave up a few amps to keep them on the boat. Good luck.

I took the provisions mentioned, The jaw slides and eye ends are either pinned in or bolted in thru fashion. There is a diagonal coming from the bimini frame to the pedastal then back to the combing so it forms a triangle that limits the pedestal pressure do a downward force. I built a dash inn this triangle that houses radar chartplotter and autopilot controls. Its got hard stainless downrods and crossrods between frames. The corners of the panels on the outboard end are strapped down independently with double 5000lb test polyester webbing with a hd strap snap and heavy connections. The ends of the panels that adjoin are pinned to brackets attached to frame. As for the canvas its built with topgun fabric which is the strongest marine cover fabric to start with, then doubled all the ends and sewn 2" webbing at all edges, under all stainless bars. and in the tails. In lieu of zippers on the skirt panels I used aluminum awning rail and welt, the rail is riveted to the 2" web reinforcing sewn in with snap buttons on 4"centers. I sailed down the east coast of florida from ft pierce to Miami with winds gusting to 50kts and higher and the enclosure didnt complain. Do have to remember to lash it down after tilting them towards the sun, had one flip up and break the bar it was mounted to when I was negligent.

[prroots]

Originally Posted by Cotemar

prroots,

Do your panels lay flat also or are they always tilled?
Why not use standard waterproof MC4 connectors?

http://www.cruisersforum.com/forums/...tml#post880732

Thanks. First off our panels can be tilted.

Do you want the short or long connector version? OK, I'll try to keep it short. The panels were delivered with 4 mm2 twistlock Radox connectors as shown on page 29 here:

http://www.alhof.com/cataloghi/cat_p011_f2003.pdf

These are quite uncommon and we finally had SolarBlvd find a source of mating connectors and drop ship them to us. Having fitted the mating connectors onto the cable coming from controller we were able to configure the two panels in series. Note: to configure in parallel we would have also needed two Y-adapter which, near as we can determine, don't exist for Radox.

Now that we've studied the parallel vs series issue, we have decided to test the panels in both configurations. Note: Morningstar, makers of our TriStar MPPT 45 controller, advised us to configure in series for a light shading scenario. We snipped off all the Radox connectors and replaced them with standard terminal lugs fed into a watertight junction box to a terminal strip. This allows us to switch back and forth at will. Right now we're testing in parallel mode in the horizontal position. We're using horizontal only because there exists historical data for our location and time of year for this configuration to compare against. Stay tuned for the results.
Pete
PS we did remember to up the fuse on array side of controller since in parallel we get twice the current

[prroots]

Originally Posted by jdoe71

Man, I'd be concerned about a good wind taking that whole structure right off the boat. Are the ends on your SS rods through bolted and not just held on by those little set screws? Hope your panel frames are bloody stout. I have similar size panels and in a good breeze there is a pile of load on them. Mine are mounted much lower and more securely than yours, I gladly gave up a few amps to keep them on the boat. Good luck.

The ends of all stainless steel tubes are actually welded to the eye ends; no set screws for us! The panels are dropped into an aluminum frame made from massive 2 X 2 X 1/4 inch anodized aluminum angle. The long sides of frame are then interconnected with four separate pieces of 4 X 1/4 inch anodized aluminum flat stock. This frame should add enormous stiffness to the panels; we're definitely not relying on the panel frames themselves. The stainless steel support structure is braced in both the athwartship and fore and aft directions. Our installer figured the weak link was the four plastic rail clamps that connect the aluminum frame to the stainless steel structure. We did provide enough mounting surface to add more if needed. BTW, the height was dictated by not having the bimini shade the panels while tilted by up to 30 degrees in the forward direction. We calculate that we've added 110 pounds to the top of the dinghy davits. Since we carry the dinghy on the foredeck when underway, this weight is in place of the dinghy not in addition to it.
Pete

[prroots]

Originally Posted by Cotemar

Wire them in series if they are side by side.
Wire in parallel if each panel is located in different locations on the boat.
MPPT controller does what’s best for either wiring scenario.

Thanks. We'll be testing it both ways; standby for results
Pete

[Cotemar]

prroots,

Do you have pictures of the panels flat.
In the picture I see solid forward bars, so I do not see how to tilt the panels.

Most people are using telescoping bars to make the tilt adjustment.

[senormechanico]

Originally Posted by jdoe71

Man, I'd be concerned about a good wind taking that whole structure right off the boat. Are the ends on your SS rods through bolted and not just held on by those little set screws? Hope your panel frames are bloody stout. I have similar size panels and in a good breeze there is a pile of load on them. Mine are mounted much lower and more securely than yours, I gladly gave up a few amps to keep them on the boat. Good luck.

I was thinking the same thing, not to mention how much windage that would be going to weather...

[hellosailor]

Pete, you might want to ask the mppt maker, or check their manual to see if it mentions efficiency versus voltage. Sometimes the controller itself may be a couple of percent more efficient at a hgher voltage, sometimes not. Of course if you've got long wire runs, putting them in series will also help to counter the voltage drop from the extra wire length.