PV Gap

Marshall Said:

Is there a maximum length of wire that can be ran with a Solar Panel?

We Answered:

There are two issues that affect the maximum length of a wire that can be used. The first is the gauge of the wire and the second is the current that is being used.
If the resistance of a length of wire is 100 ohms and the current that is going down the wire is 1 amp then V=IR, so the voltage drop on the wire is 100 volts. If the resistance is 50 ohms and the current is 1 amp then the voltage drop is 50 volts. Your resistance and current are no where near those values. When making calculations you have to remember the length has to include from the panel to the battery and back from the battery to the panel.
I have included the a web site that will allow you to calculate the voltage drop on the loop. The other thing to remember is that as the battery charges and the voltage in the battery increases then the current decreases, which also means that the voltage drop in the wires decrease as well.
Using the calculator, a 20 foot piece of wire with a current of .25 amps, will produce a voltage drop of 0.0518 in the wires, using 20 gauge wire, which is a lot smaller than the 14 guage wire that is in your house electrical system. If you used 2 conductor 14 gauge wire the voltage drop would be 0.0129 over the 20 foot loop between the panel and the battery, this should not be significant.
Put the maximum current provided by the panel and then you can calculate the gauge of wire that you would need to use.

Willie Said:

Will a solar panel work without sun?

We Answered:

I have a solar battery charger, It produces some output on even the cloudiest of days. I leave it connected all of the time, and I never have a dead battery. Those things are slow. The main thing is patience. If you try to start the boat, and it doesn't work, you have just killed the battery again. The best thing to do is hook it up today, and start the boat tomorrow.

Claire Said:

what materials should a solar panel and wind turbine be made out of if it is going on a boat?

We Answered:

Hello Ashlea...take a look at this link...
http://www.analyzemath.com/CircleEq/Tuto…
These can be interlaced into the hulls deck or can be rolled into tubes. Formed to fit a shape. As far as the wind generator goes the housing should be PVC all metal should be stainless and the windings and core should be copper. All in a basic weatherproof enclosure. there ya go from the E

William Said:

What are the calculations I have to make to buy the right motor and solar panel for a small boat?

We Answered:

Normally a boat like that would be fitted with up to a 4hp outboard.

1hp = 750w (approx.), so you're looking for up to 3kw of power.

3kw from a 12v battery will draw a maximum of 250A.

After that you need to decide how many hours a day you need to use the boat for in order to decide your battery capacity; they'll need to be deep-cycle batteries which you can discharge heavily and the battery supplier can tell you the charging rates suited to your chosen batteries which in turn determines the size and type of solar panels which you use. In any case, your project is only likely to be fully solar-powered if you live in a sunny climate and have a large solar canopy on your boat. Or you could be inventive and tow the solar panels behind on a pontoon to minimise drag and keep the boat from being top-heavy. If the pontoon also carried some or all of the batteries then your most expensive parts will be on a separate module which can be safely stored away from the boat and you'll also be able to experiment with different battery packs and solar panel combos. It also allows you to have one power pontoon on charge (possibly even a mains top-up) whilst the other is in use.

When you calculate the daily running time you'll need to guesstimate the percentage of the time you'll be running at full-throttle. If it's close to 100% then it's a good idea to add 50% to your running time: this not only gives you a safety margin but it also prolongs battery life and compensates for the fall-off in charge capacity which the batteries will suffer over time. If you're only at full throttle 25% of the time and around 50% for the rest then you don't really need to add a margin.