Solar Choices

[s/v Jedi]

Originally Posted by noelex 77

The wire size certainly needs to be much greater for parallel connection and as Jedi points out you should take the cost difference into account when deciding on your system. Also consider the difficulty of installing large cables.

However, cabling with a resistance of 0.1 Ohms would be totally inappropriate for a 36A system so it is not a realistic example. The voltage loss would be 3.6v at full output.

I have seen worse…..

[CarinaPDX]

A couple of points:

Since a solar panel is a current source, and the operating voltage is determined by the battery's ability to accept that current, the current remains the same regardless of, say, a 1V drop in the cables. Assuming that it is operating to the left of the knee in the I-V curve. So the panel voltage would be 1V higher. The loss in the wire is compensated by the increased output of the solar panel (same current, higher voltage at the panel). Basically some of the panel's potential output that is not realized in shunt controllers is now wasted in the wires instead of not being created in the first place. No big deal.

My main point is that installing a solar charging system requires a systems approach. When it comes to cabling it is important to correctly size the cables (panel to battery) with an eye towards the maximum voltage drop. Also diode drops and drops through the controller (remember, junction transistors have 2 diode drops) must be considered. In this regard 12V nominal systems do require special care, and sometimes pretty large cables. Which is back to the point that large solar systems are a no-brainer for MPPT controllers, but small ones may not be worth it. It will depend entirely on the specifics of the system; there is no one size fits all.

Greg

[beiland]

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[senormechanico]

Originally Posted by s/v Jedi

I have seen worse…..

LOL ! I once helped out a guy in Mexico who had 1200aH bank in his bilge (44' boat) with a solar array on the stern.
He said it had been installed by a guy in San Diego who "knows everything about electricity".
He couldn't figure out why his bank was at 10.5v. when he read 14.8v. on the panel (no regulator).
I pointed out his 22 gauge Radio Shack speaker wire used as solar feed...

[COLINFLTENG]

he had only 14.8v at pannels

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[zboss]

FYI... I just ordered a couple of Genasun controllers and since they are not field programable, I was able to get them programmed to custom settings for my Trojan batteries at the manufacturer.

The bulk/absorption was increased from the off-the-shelf 14.4/14.6 to the Trojan recommended 14.8 and the float was set to 13.2 from the 13.5 the Genasun is normally set to.

[cealpotts]

Just went with the Solar Stik. Amazing! Have had solar panels before, and they are nothing compared to this new set up. It's a transom mount unit. Also went with the Primus Air Breeze 160 on top. Here's a link to my review - includes bits about the installation, too. Always GO, never regret | Major upgrade: Solar Stik added to IP 27

Ceal
s/v Time Goes By
Island Packet 27

[senormechanico]

Originally Posted by COLINFLTENG

he had only 14.8v at pannels

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Smallish panel, under load from DEAD, BIG FLA bank.
This was a long time ago (1995) and that voltage was actually about in the middle of the aforementioned wiring at his monitor readout.
The voltage at the panel was about 18.

The guy told me he had "a steep learning curve ahead".
No kidding.

[wdkester]

Originally Posted by cealpotts

Just went with the Solar Stik. Amazing! Have had solar panels before, and they are nothing compared to this new set up. It's a transom mount unit. Also went with the Primus Air Breeze 160 on top. Here's a link to my review - includes bits about the installation, too. Always GO, never regret | Major upgrade: Solar Stik added to IP 27

Ceal
s/v Time Goes By
Island Packet 27

$4000 MSRP for the solar stick would buy lots of Panels even if the were hot AND shaded.

Isn't the wind gen going to shade the panels at noon +- 2 hours?

[s/v Jedi]

Originally Posted by wdkester

$4000 MSRP for the solar stick would buy lots of Panels even if the were hot AND shaded.

Isn't the wind gen going to shade the panels at noon +- 2 hours?

Here it's in action: one panel already shaded and taken out of production:

[pickpaul]

Isn't that just operator error? Mast needs rotating into sun?

[Emmalina]

Just my two bob's worth.. Don't buy anything with a fan in it !!! I have 2 morning-star controllers and they work great AND silently. I have 3 300w semi flexible panels on a hard top and they are on aluminium backing . Great for heat dispersion and light. They are in series so my cable diameter is greatly reduced they come in at about 130v. I also have 3 85s on the davits run by another MPPT morning-star again in series. I have a lot more power than i need but hey its free.... My inverter has fans and i find it very annoying. So does my battery charger when in a marina...Just my opinion,,

[senormechanico]

Originally Posted by s/v Jedi

Here it's in action: one panel already shaded and taken out of production:

Made the same mistake in 1993.
Got wise in 1994 and chopped off the wind generator and pole above panels.

Got MORE power than before. DUH !

[poppyduc]

Go as big as you can afford, In Aus I have heard everyone is going for 250watt panels are very cheap here now as everyone has them on their houses now. Making the whole solar market cheaper. being 24volt regulated down to 12 volt they seem to produce power even on cloudy day as they easily produce 12 volts on these dull days?

[COLINFLTENG]

I have two 250 watts ordered Canadian solar made in Canada eh

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