Solar to mineral accretion underwater!

[sensij]

That is impossible to happen. The whole system is one huge ground fault, and the source of energy is the panel and Mr Kirchoff Law applies to any power system. All current leaving the panel returns to the panel. Basically it is a Cathodic Protection System on a very small scale.

Yep, I'm going to have that 2nd cup of coffee today.

[Sunking]

Yep, I'm going to have that 2nd cup of coffee today.

No worries my friend, we all have days when we fail to see the Forrest with all the trees getting in the way.

[Sunking]

Why your electrodes are getting eaten away - dissimilar metal corrosion

Steel and Aluminum:

http://en.wikipedia.org/wiki/Galvanic_corrosion#US_Navy_Littoral_Combat_Ship_Independence

Gonna cost big to fix that blunder.

And the other answer, is you are "electroplating" the aluminum to the steel. reversing the circuit polarity may retard the action, but it may not biologically, be the effect you want.

Like any Cathodic Protection system you sacrifice the anode to protect the cathode. That is how pipe lines and ships protect themselves from corrosion. It is also used to protect Lightning Protection Systems at places like Disney and all airports. Disney in Orlando has the state of the art LPS using Cathodic Protection. Most people are not aware the Disney parks in Orlando are huge 2-story building because all they see is the top floor above ground. There is a whole other world just beneath their feet.

[Sunking]

Maybe ours is working but very slowly due to the minimal voltage reaching the anode and cathode, after all the aluminium is bubbling and corroding. I just more want to understand it all properly and then work out if we can make it more effective/get more voltage to the structure.

Solar Marine what is not soaking in is you do not appear to understand what a current source is and how a solar panel works. It is really very easy to understand. The key to understanding is a few of Ohm's Law Equations. The most important one is Voltage = Current x Resistance

A solar Panel as I have stated many times is a Current Source, a very soft Current Source. The current a panel produces is directly proportional to the amount of sunlight strikings its surface. When used in the manner you are using the panel will be in the Isc or Current Short Circuit Range. All short circuit means is very low resistance.

In your application you want to generate as much current as you possible can. Voltage is not much of a concern because you are shorting out the panel well below the Vmp region. Your 50 watt panel is designed to operate into a resistance of 6 Ohms up to infinity aka open circuit. However your application requires something between 0 and 1 ohm or the exact opposite of what the panel was designed to do.

So essentially you are shorting out the panel with 1 Ohm. You 50 watt panel has two current ratings Imp and Isc. You wil be operating very close to Imp range and that should be around 3.2 amps. But do not be fooled into thinking you will ever see that much current because you never will. That is a laboratory measurement under ideal controlled conditions of 1000 watts per square meter light source, 25 C panel temperature, and 0% humidity. You will never now one minute from the next what current you will see. At noon under crystal clear skies on a cold day you might see 80% of that reading for a few minutes around noon if the panel is facing directly into the sun.

The current you will experience if graphed out on time vs magnitude will be a Bell Curve. Starting at sun up just a few milli-amps. As the sun rises higher in the sky the current begins to rise. It continues to rise until you reach solar noon. Whjat value that current is will depend on many factors. If it is cloudy just about 1/10th of what you would get on a bright sunny cold day with low humidity. At best with your location and climate maybe 2 amps for a few minutes around solar noon. Then after solar noon the process reverses.

So when all is said and done at the end of the day, the panel will have generated some 5 to 8 Amp Hours over the course of a 24 hour cycle when Amp Hour = Amps x Hours. So you can use your panel as configured, it will work but just very inefficiently. What you are looking for in a panel is as low of voltage as you can find with as high of a current as possible to get your daily average as high as possible. For a manufactured product that is going to be a standard battery panel of 22 Voc 17 Vmp as high of a wattage as you can afford.

As for voltage at the electrodes this is where Ohm's law comes into play. There are two resistance elements in play that make up total circuit resistance. The Wire Resistance and Electrode Resistance. The voltage you see at the panel is a product of the current and Total Circuit Resistance. Going back to Ohm's Law using your observed numbers you seen something like 1.7 volts @ 2.5 amps which is in line with your panel maximum current. By using Ohm's Law we know RESISTANCE = VOLTAGE / CURRENT = 1.7 volts / 2.5 amps = .68 Ohm's. What you do not know is what is the value of the Wire Resistance and Electrode Resistance are at this point in time. All you know is the total resistance of the circuit.

The only resistance you can control is the wire resistance. You can control the electrode resistance somewhat by the spacing and size of the electrodes, but I assume those are fixed at this point so no use working that part. That just leaves you the wire resistance. Ideally you want the wire resistance as low as you can get, or I should say can afford. Wire resistance is controlled by length and size The shorter and larger, the lower the resistance. So lets say Wire Resistance = Electrode Resistance of .33 Ohms for a total of .66 Ohms. You measure at the panel 1.7 volts and 2.57 amps. What is the electrode voltage. Two easy ways to find that answer. We can use Ohm's Law or a simple ratio equation. Either way it comes out to .85 volts

2.57 amps x .33 Ohms = .85 volts

or

[.33 Ohms / .66 Ohms] x 1.7 volts = .85 volts

Since this will be a Passive System using a panel in the Isc range you have no control of current other than the size of the panel wattage and time of day. In the morning when sun angles are low and th epanel is only generating say .1 amps you will measure .1 amps x .66 ohms = .066 volts at the panel which means you have .033 volts at the electrodes. You have to take what you get by only using a passive solar panel.

The experiment you linked to used a solid controlled current source providing s steady sate current over a 24 hours period. So at 2 amps over 24 hours delivered 2 amps x 24 hours = 48 amp hours. You 50 watt panel even though it can produce up to 2 amps briefly for a few minutes in a day at best can only generate 8 Amp hours in a 24 hour period.

[sensij]

Understanding what Sunking is saying is important if you want to have more confidence in what the solar panel is doing. Going back to your original question, what do you next?

1) Make sure you don't have a circuit path that bypasses the cathode. In other words, make sure the copper wire for the cathode is not wet, or in contact with a metal structure that has continuity to the anode.

2) Make the cathode smaller

3) Get a bigger solar panel

4) Dumb question, but you are using seawater, right? If the Ca and Mg content isn't there, it can't build up.

The solar panel is doing what it is supposed to.

[Sunking]

Understanding what Sunking is saying is important if you want to have more confidence in what the solar panel is doing. Going back to your original question, what do you next?

1) Make sure you don't have a circuit path that bypasses the cathode. In other words, make sure the copper wire for the cathode is not wet, or in contact with a metal structure that has continuity to the anode.

That would mean using a cable insulation type rated to be submerged in seawater under pressure. Otherwise salt water is going to make about all cable insulation types conductive and leak current.

[Solar_Marine]

Solar Marine what is not soaking in is you do not appear to understand what a current source is and how a solar panel works. It is really very easy to understand. The key to understanding is a few of Ohm's Law Equations. The most important one is Voltage = Current x Resistance

A solar Panel as I have stated many times is a Current Source, a very soft Current Source. The current a panel produces is directly proportional to the amount of sunlight strikings its surface. When used in the manner you are using the panel will be in the Isc or Current Short Circuit Range. All short circuit means is very low resistance.

In your application you want to generate as much current as you possible can. Voltage is not much of a concern because you are shorting out the panel well below the Vmp region. Your 50 watt panel is designed to operate into a resistance of 6 Ohms up to infinity aka open circuit. However your application requires something between 0 and 1 ohm or the exact opposite of what the panel was designed to do.

So essentially you are shorting out the panel with 1 Ohm. You 50 watt panel has two current ratings Imp and Isc. You wil be operating very close to Imp range and that should be around 3.2 amps. But do not be fooled into thinking you will ever see that much current because you never will. That is a laboratory measurement under ideal controlled conditions of 1000 watts per square meter light source, 25 C panel temperature, and 0% humidity. You will never now one minute from the next what current you will see. At noon under crystal clear skies on a cold day you might see 80% of that reading for a few minutes around noon if the panel is facing directly into the sun.

The current you will experience if graphed out on time vs magnitude will be a Bell Curve. Starting at sun up just a few milli-amps. As the sun rises higher in the sky the current begins to rise. It continues to rise until you reach solar noon. Whjat value that current is will depend on many factors. If it is cloudy just about 1/10th of what you would get on a bright sunny cold day with low humidity. At best with your location and climate maybe 2 amps for a few minutes around solar noon. Then after solar noon the process reverses.

So when all is said and done at the end of the day, the panel will have generated some 5 to 8 Amp Hours over the course of a 24 hour cycle when Amp Hour = Amps x Hours. So you can use your panel as configured, it will work but just very inefficiently. What you are looking for in a panel is as low of voltage as you can find with as high of a current as possible to get your daily average as high as possible. For a manufactured product that is going to be a standard battery panel of 22 Voc 17 Vmp as high of a wattage as you can afford.

As for voltage at the electrodes this is where Ohm's law comes into play. There are two resistance elements in play that make up total circuit resistance. The Wire Resistance and Electrode Resistance. The voltage you see at the panel is a product of the current and Total Circuit Resistance. Going back to Ohm's Law using your observed numbers you seen something like 1.7 volts @ 2.5 amps which is in line with your panel maximum current. By using Ohm's Law we know RESISTANCE = VOLTAGE / CURRENT = 1.7 volts / 2.5 amps = .68 Ohm's. What you do not know is what is the value of the Wire Resistance and Electrode Resistance are at this point in time. All you know is the total resistance of the circuit.

The only resistance you can control is the wire resistance. You can control the electrode resistance somewhat by the spacing and size of the electrodes, but I assume those are fixed at this point so no use working that part. That just leaves you the wire resistance. Ideally you want the wire resistance as low as you can get, or I should say can afford. Wire resistance is controlled by length and size The shorter and larger, the lower the resistance. So lets say Wire Resistance = Electrode Resistance of .33 Ohms for a total of .66 Ohms. You measure at the panel 1.7 volts and 2.57 amps. What is the electrode voltage. Two easy ways to find that answer. We can use Ohm's Law or a simple ratio equation. Either way it comes out to .85 volts

2.57 amps x .33 Ohms = .85 volts

or

[.33 Ohms / .66 Ohms] x 1.7 volts = .85 volts

Since this will be a Passive System using a panel in the Isc range you have no control of current other than the size of the panel wattage and time of day. In the morning when sun angles are low and th epanel is only generating say .1 amps you will measure .1 amps x .66 ohms = .066 volts at the panel which means you have .033 volts at the electrodes. You have to take what you get by only using a passive solar panel.

The experiment you linked to used a solid controlled current source providing s steady sate current over a 24 hours period. So at 2 amps over 24 hours delivered 2 amps x 24 hours = 48 amp hours. You 50 watt panel even though it can produce up to 2 amps briefly for a few minutes in a day at best can only generate 8 Amp hours in a 24 hour period.

]

Thank you for this, I'm sorry for what may seem a lack of understanding but this message has helped a lot!

[Solar_Marine]

Understanding what Sunking is saying is important if you want to have more confidence in what the solar panel is doing. Going back to your original question, what do you next?

1) Make sure you don't have a circuit path that bypasses the cathode. In other words, make sure the copper wire for the cathode is not wet, or in contact with a metal structure that has continuity to the anode.

2) Make the cathode smaller

3) Get a bigger solar panel

4) Dumb question, but you are using seawater, right? If the Ca and Mg content isn't there, it can't build up.

The solar panel is doing what it is supposed to.

Yes using seawater,

After now understanding what sunking is saying I get it,

Basically it is all working now I am sure, just very inefficiently to say the least so mineral deposition will take much longer then in the experiment I linked to,

Making the cathode smaller is one option, I have some more questions,

1) The anode is currently quite close to the cathode, I can't find any literature on this but the closer/further away it is from the cathode does that affect resistance or in your guys opinion anything to do with the setup?

2) Maybe a very silly question but will 2 solar panels do the same as a 'bigger' panel? Say 2 50w panels wired in series....?

Thank you to you both as my understanding now is much better of the electrical system, (even though a very easy one for most...)

[Sunking]

]

Thank you for this, I'm sorry for what may seem a lack of understanding but this message has helped a lot!

No reason to apologize. If you are scientist the math will sink in and you will get it. Just keep in mind using a small wattage panel in a passive system is going to be very limited and there is not much can do to control things. To get control and optimum results takes quite a bit more money and hardware to gain control. Your lab paper was just that, no budget restraints under ideal conditions and full control.

About all you can do to make the most of it is make the wire resistance lower than the electrode resistance. Wire resistance is pretty easy to calculate and I can help you with that. Wire specifications are given at specified temp in Ohm's per kilometer or 1000 feet so it is a real straight forward process of ratios.

[sensij]

1) The anode is currently quite close to the cathode, I can't find any literature on this but the closer/further away it is from the cathode does that affect resistance or in your guys opinion anything to do with the setup?

I could see the distance affecting the chemistry, some space around the electrodes would be needed to allow the ion concentrations to accumulate. It isn't really going to affect the electrical flow. Even if you (try to) add resistance by increasing the distance, the current flow will be pretty much the same.

2) Maybe a very silly question but will 2 solar panels do the same as a 'bigger' panel? Say 2 50w panels wired in series....?

Two panels in series raises the voltage, which doesn't help. Two (or more) panels wired in parallel would proportionally increase the current, which would help. Just make sure they are similar panels (all 12 v panels, like the one you have now).

Edit: As Sunking mentioned earlier, lower voltage panels would be more efficient for this type of operation, but I'm not sure there is anything that would be more cost-effective than buying additional 12 V panels. When looking at cost-effectiveness, don't focus on the voltage or power, focus on the current.

[sensij]

About all you can do to make the most of it is make the wire resistance lower than the electrode resistance. Wire resistance is pretty easy to calculate and I can help you with that. Wire specifications are given at specified temp in Ohm's per kilometer or 1000 feet so it is a real straight forward process of ratios.

It is hard to see much opportunity to improve wire resistance, except by moving the panel closer. Even then, the OP states that 16 mm diameter copper is being used, which would have a resistance of less than .05 ohms / 1000 ft. Just not much to be gained there.

[Sunking]

It is hard to see much opportunity to improve wire resistance, except by moving the panel closer. Even then, the OP states that 16 mm diameter copper is being used, which would have a resistance of less than .05 ohms / 1000 ft. Just not much to be gained there.

I did not catch the wire size, and you are right once you get to a point there is diminishing returns and going to even larger wire is pointless and just throwing money away.

[Sunking]

Making the cathode smaller is one option, I have some more questions,

1) The anode is currently quite close to the cathode, I can't find any literature on this but the closer/further away it is from the cathode does that affect resistance or in your guys opinion anything to do with the setup?

Yes the closer they are, the lower the resistance.

2) Maybe a very silly question but will 2 solar panels do the same as a 'bigger' panel? Say 2 50w panels wired in series....?

Not a silly question at all, just your learning curve about current sources and series parallel circuits.

In a Series circuit voltage adds, current remains the same. In Parallel circuits current adds and voltage remains the same.

You are operating the panels below Vmp and in the Isc range which means you have no use for voltage. You could add 10 of those panels in series and it will not add 1 single volt to the circuit because your current would be the same as a single panel of 2 to 3 amps. You would add panels in parallel to add the current.

Here lies the efficiency problem. At noon bright sun you rpanel will generate around 3 amps through .66 Ohms. Back to Ohms law again that means your 50 watt panel operating as a pure current source is only generating Amps x Amps x Resistance = Watts. Do the math with 3 amps and .66 Ohms and see what you get. Did you come up with 6 watts?

Now if you had a converter we could get you the same 2 volts but at 25 amps of current or Volts x Amps = Watts. So 2 volts x 25 amps = 50 watts.

The key to your understanding is the Math OHMS LAW and the formulas that use the variables I = Current measured in Amps, and R = Resistance measured in Ohms. Click on the image below.

Ohm's_law_formula_wheel.JPG

Here is another crazy example. You could go out a buy a Grid Tied Panel rated for 150 volts that has a rating of 50 volts Vmp and ISC of 3 amps would do the exact same thing as your 50 watt battery panel you would get the same current and 6 watts out of it. Why because the current ratings are the same. You want current, not voltage.

[Solar_Marine]

Thank you for the replies guys,

I can now see that the structure is working a depositing minerals,

Another question about wiring panels, is it possible to wire two different panels in parallel? If so how close do their specs have to be? The company have sold out of the 50w panel I am currently using,

Thanks

[Sunking]

Thank you for the replies guys,

I can now see that the structure is working a depositing minerals,

Another question about wiring panels, is it possible to wire two different panels in parallel? If so how close do their specs have to be? The company have sold out of the 50w panel I am currently using,

Thanks

In your application not much to worry about as all you want is current and as much as possible. Panels you are using are the 36 cell types made for 12 volt battery systems. Those all have roughly the same Voltage at Maximum Power of 17 to 18 volts. Having said that, the highest powered 36 cell panel you can afford. You could even use 18 cell panels or 6 volt battery panels. Only thing to do is wire it in PARALLEL, not in series and you are good to go.