I work on lots of boats that are sailed off of moorings and as such they tend to have very short battery life no matter what brand or how expensive. Some types tolerate this type of environment better than others but none like it. Batteries like to be topped up to 100% as often as possible. When batteries are not topped up sulfation forms on the battery plates and they begin to suffer and die.
When you are off cruising or sailing from a mooring your battery bank will rarely if ever get back to 100% state of charge. Most cruisers cycle their banks between 50% SOC and 80-85% SOC. This is because of what is known as "battery acceptance". The long and short is that in order to top your bank off to 100% would take many, many hours of running the engine, like 10+ hours.
As batteries charge they accept less and less charging current. Rapidly declining acceptance begins around 80% state of charge. Putting the last 20% in with a diesel engine is simply a waste of energy and not the best thing for your engine unless you're running under power or motor sailing for long periods of time.
For a few hundred dollars you can greatly extend the life of your bank and start each weekend adventure with a battery bank at or darn near full.
Panels:
Today there are not a lot of quality manufacturers building small panels suitable for marine use. Most are building panels in the 100+ watt range these days. For small panels I have been installing panels from SunWize and, while not the quality of a Kyocera, they have been of decent quality. Some manufacturers specifically exclude marine use in their warranty to check with them before you buy a solar panel for marine use.
Mono & Polycrystalline - These are by far the most long lived and efficient solar panels per sq in. These are almost always rigid panels in an extruded aluminum frame with tempered glass not an EVA skin. These panels are more prone to shading issues but also have about double the output per sq in when compared to most flexible panels. Glass covered arrays also do not suffer from a flexible EVA cover deteriorating from the sun's UV rays and can often offer better UV protection to the cells.
While Dupont has pushed the envelope on EVA films, and it has gotten better, a quick look at many of the warranties will show a difference between flexible and rigid panels. Kyocera for example warrants their panels for marine use and a minimum of 95% output for 20 years. Some EVA panels are warranted at 90% from year 1 and at only 80% output starting at year 10, the Kyocera's are warranted at 95% output at year 20, and they've actually been around longer than their warranties have been in place...
Amorphous Panels - Amorphous panels are made differently and by their nature require nearly double the surface are to equal the same watts in a mono or polycrystalline panel. They are upwards of 50% less efficient than a good mono or polycrystalline panel.
In the marine space many of these panels are made to be flexible which can make them even less efficient. The combination of a flexible EVA lens, that can slowly degrade in UV, and the fact that one side may not be aimed at the sun if "flexed", say over a boom, can often mean very little output for the sq in you have out there. Even in perfect conditions you still need a lot more space for an amorphous panel than you would a mono or polycrystalline panel. Yes they can be convenient but you need to weigh the benefit/space/cost & efficiency issues too.
While there are some high efficiency flexible panels that are not amorphous, such as the Solbien's made in Italy, that compare in output to the rigid panels, they are quite costly compared to rigid panel at nearly triple the cost or more. Ganz also makes some efficient smaller panels but again the price is about double or more what a rigid panel costs. If that convenience is worth it, then they are a good deal.
The neat thing about the Solbien panels is that they can be sewn right into a bimini top and have no sharp edges. Some of the solo round the world racers are using this technology and, good for us, it will eventually trickle down. Due to the flexible nature however they will probably suffer from UV degradation faster than a comparable glass encapsulated panel.
Amorphous panels do have one benefit and that is they are less prone to shading issues than a mono or polycrystalline panel this benefit however can be quickly dwarfed by the real estate needed to equal the output of a rigid panel..
Wiring:
The wiring of your panel to the boats battery bank is critically important. Most decent 12V panels will output a voltage of around 16.0 to 18.5 volts +/-. Giving up any of this voltage to voltage drop can affect how quickly your bank is recharged. If you're using an MPPT controller voltage drop should be almost nothing to maximize performance. I like to size panel wiring for a 1-2% voltage drop max.
Controller:
Any panel sized to actually "recharge" your bank will need a solar controller. There are vast quality ranges amongst controllers and a bad controller can be a complete waste of money and wreck the efficiency of your system.
There are essentially three types of controllers;
MPPT = Multi-Point Power Tracking - These controllers take excess voltage and turn it into current rather than wasting it. When you consider most 12V panels will supply a voltage in the 18V range, and that your battery bank really should not be charged in excess of 14.6V or so, that can leave wasted and unused energy potential. The idea and concept of an MPPT controller is that it takes any excess voltage and converts it to charging current. It is more complicated that that but in a nut-shell that is what they do.
Most MPPT controllers will work best when your array gets over 150-180 watts in size and you really do have "excess voltage".. The Genasun MPPT controllers are specifically engineered for small panels below 150W and are the only MPPT controllers I know of specifically designed as such. They extract the max current they can out of small panels.
PWM = Pulse Width Modulated - These are the best alternative to an MPPT and they charge quite efficiently but can not turn excess voltage into current.
Shunting Controllers = These controllers shunt or switch the panel current/voltage OFF when a preset voltage is reached and then turns back on when the battery bank voltage drops to a second preset ON voltage. These are the least desirable controllers and are best avoided. If a controller does not specifically say PWM or MPPT is is probably a cheap shunting controller. I do not advise spending your hard earned money on shunting controllers for sailboats.
Why?
These devices begin switching on/off once the bank hits absorption voltage and can really cut your time to full by days, not minutes.
In the case of some of the Sunforce controllers, often sold at West Marine, they switch OFF at around 14.2 volts and they do not switch back on again until 13.0V. This may be fine for an "off grid" application where you often have a load that sucks the bank back to 13.0V very quickly, but, with a boat on a mooring, with no loads, it can take a healthy bank a LONG time to drop the surface charge back to 13.0V.
I have some customers with banks of AGM & deep cycle wet cells batteries that will sit at over 13.0V for well over an hour, and this is at 70F. When colder they hold the voltage higher for even longer. That is an hour of lost charging time waiting for a cheap shunting controller to switch back on and provide maybe 60 seconds of charging before raising the bank to 14.2V and then shutting off again. Sometimes these cheap controllers will never restore the bank to full, no matter how big the array, in the time you need them to.
Below is a video of one of the "better quality" shunting controllers, a Flex Charge PV-7. It shuts OFF at about 14.4v and does not come back on until the bank voltage has dropped to about 13.6V. The first video is showing the "current" but you can see it turn on and off. I applied a load of 0.1A just so it would go to -0.1A when OFF for the video. When you get close to full your OFF time can be as much as 10-20+ times longer than your on time with some cheap controllers.
The second video is showing the voltage behavior.
In this case the "ON" time is about 5-6 seconds and the OFF time close to a minute to get the bank back down to 13.6v before it can turn back on again. This bank still had 20 Ah's to go and it would take 5-7+ days for this bank to eventually get "full" from an 80-85% state of charge with 5-6 seconds on and 60 seconds off, remove the 0.1A load and it would likely make this even longer..
It should be noted that before I took these videos the banks were charged to full using a shore charger until they were accepting less than .5% of C (capacity) at 13.6 volts. At this point, after being on float for two days, the battery monitor was re-calibrated manually to read "full". I then applied loads and removed approx 30 Ah's from the bank. The solar re-charge time was then monitored and the time it took to replace the 30Ah's removed calculated.
Contrast that Flex Charge controller, or a Sunforce, with a quality PWM or MPPT like the Genasun MPPT or a Morningstar Pro-Star 15 PWM controller and the difference in the last 15% of charge, and the time it takes, can be quite dramatic.
I recently replaced both a Sunforce and a Flex Charge shunting controller with Genasun MPPT controllers. On one boat "FULL" was cut from averaging 7-8 days to about 2 days and on the other boat "FULL" was cut from roughly 5-6 days to about 1.5 days. Same boat, panels, wiring, batteries, just a much better quality controller that does not turn ON/OFF like a cheap shunter will. A lot of the controllers you buy from "discount" solar houses & eBay sellers are "shunters"...
If you stick with Morningstar PWM, starting at the Pro-Star series, Blue Sky, Genasun and a couple other reputable controller manufacturers, you'll be doing well. I've found the eBay stuff is very often a scam, so be careful. There are surely other quality manufacturers out there but Blue Sky, Genasun, Morningstar & Outback are among the most respected and widely used.
I have replaced a number of eBay, so called, MPPT controllers that were not MPPT at all but rather simple shunting controllers. MPPT & PWM controllers do not shut off for long periods of time like shunters do.
The Genasun MPPT's are a very good value for smaller for panels. Under 150W, that is pretty much all I am installing these days, unless I have a bigger array, and then I'll use Blue Sky or Morningstar.
Please be careful with "cheap" controllers as you often get what you pay for.
I generally buy from Northern Arizona Wind-Sun, Wholesale Solar, eMarine and a few others. I pay a little more but I know the quality is good and they hold up in the marine environment.
Connecting It To The Boat:
A solar panel sized to re-charge should ideally be routed directly to the house bank. You can then use a device like an Echo Charger to send a small charge over to the start bank to keep it topped up. Even without a solar panel an Echo Charger is a tremendous device. It should go without saying that anything connected directly to a battery bank should be fused.
Sizing:
How do you size this? At a minimum a 1.0A to 3.5A panel can be okay depending upon the size of your bank and depending upon which charge controller you use. You can easily go beyond 15A with solar but you need some real estate to devote to it.
Ideally you want the alternator to bring the bank back to 80-85% state of charge and then let the solar panel do the rest, when you're not there during the week. If you want to satisfy cruising needs such as refrigeration, instruments, AP etc. then your array will get quite large.
The faster you can bring the bank from 80% to 100% the less sulfation you will have and the longer battery life you'll get.
For a sizing example, lets look at a bank of 300 Ah's for "mooring recharge".
With simple math you can see that the last 20% of capacity is 60 Ah's. However you need to take charge inefficiencies into account too so you'll really need to put back in about 70Ah's +/- to get back to 100% state of charge.
For sailboats the panels are usually left flat when your not there so that you can capture "most" of the sun. In a land based installation the panels are fixed, the property is not moving like a boat does, and can be angled at the sun. This is not so on a boat, so panel position is very often a compromise. If you are at a dock you can rig the panels and aim them more appropriately but not on a mooring or off cruising where your boat will swing at will.
Because of this you can figure on about 4 - 4.5 hours of full output per day on average, for the Northern climates, and 5-6 hours per day the closer to the equator you get.
Some folks use 5 hours per day in the Northeast I found that to be a little to generous.. Some days it will be more some less but here in Maine 4 - 4.5 hours at full output works best.
So, a 300 Ah bank @ 20% down = 60 Ah's that need to be returned + charge inefficiency = 70 Ah's total needed for "full"
A 2.5A output panel X 4.5 hours = 12.5 Ah's/Day returned to the bank. If you have phantom loads, like a propane sniffer or other "always on loads, subtract those and that is your "net".
Next divide 70 Ah's by 12.5 and you can see that it will take approximately 5.6 days to go from 80% SOC to full on a 300 Ah bank.
That's a little long so a panel in the 3.5A output range or more would be better served. A 3.5A panel shaves a full day off the time it takes to hit full..
Shading (The Big Bad "S" Word!)
The biggest performance killer in marine solar is SHADING! You need to keep the panel out of as much shade as you can. Under the boom often seems ok, convenience wise, but your charging performance will get murdered. Even small amounts of shading can cut the panels performance by 50% - 80% depending upon the severity of the shading.
I moved one customers 40W panel from under his boom, just in front of the dodger, to his stern push pit and he went from never getting his bank to full to getting back to full in about three days. Same panel, controller and boat just eliminated about 90% of his shading issues.
Best Locations:
Bimini Top
Davits
Pole Mounted
Movable & Positioned At The Sun
Worst Locations:
Boom
Under Boom
On Deck
Dodger Top
One of the easiest locations for small panel installs is right of the stern push pit, if you do not have a bimini. If you have a bimini mounting it to the top of the bimini frame is a great location.
To mount them to a push pit I use standard dodger fittings. Do not drill the second hole until you've "fitted" it to the stern rail and marked where the angle needs to be:
This was a small 30 watt / 1.8A unit for a 200Ah bank.
For the backs of the fittings I use a decent sized fender washer and nyloc nuts. I will often put TefGel on the mating surfaces to the aluminum.
For the outer edge support strut I use what I call a flip-flop hinged deck fitting. These are not inexpensive, about $36.00, but they work really well in this application.
As you can see the tube eye simple bolts to the hinged deck fitting:
To mount everything to the stern push pit I use three "split jaws". Again, not in-expensive, but perfect for this application and it keeps the sharp edges of the panel out of the cockpit.
For stainless to stainless always use Tef-Gel to prevent thread galling:
The finished installation takes between 2 and 5 hours to mount and wire up depending upon interior access etc.:
The wiring to the battery bank could not be easier. From Panel + & - and To Battery + & -. When wiring the controller to a parallel or series/parallel bank always wire your positive and negatives "across" the bank meaning neg at one end and pos on the other end. The controller should also be mounted as close to the bank as possible.
When you are off cruising or sailing from a mooring your battery bank will rarely if ever get back to 100% state of charge. Most cruisers cycle their banks between 50% SOC and 80-85% SOC. This is because of what is known as "battery acceptance". The long and short is that in order to top your bank off to 100% would take many, many hours of running the engine, like 10+ hours.
As batteries charge they accept less and less charging current. Rapidly declining acceptance begins around 80% state of charge. Putting the last 20% in with a diesel engine is simply a waste of energy and not the best thing for your engine unless you're running under power or motor sailing for long periods of time.
For a few hundred dollars you can greatly extend the life of your bank and start each weekend adventure with a battery bank at or darn near full.
Panels:
Today there are not a lot of quality manufacturers building small panels suitable for marine use. Most are building panels in the 100+ watt range these days. For small panels I have been installing panels from SunWize and, while not the quality of a Kyocera, they have been of decent quality. Some manufacturers specifically exclude marine use in their warranty to check with them before you buy a solar panel for marine use.
Mono & Polycrystalline - These are by far the most long lived and efficient solar panels per sq in. These are almost always rigid panels in an extruded aluminum frame with tempered glass not an EVA skin. These panels are more prone to shading issues but also have about double the output per sq in when compared to most flexible panels. Glass covered arrays also do not suffer from a flexible EVA cover deteriorating from the sun's UV rays and can often offer better UV protection to the cells.
While Dupont has pushed the envelope on EVA films, and it has gotten better, a quick look at many of the warranties will show a difference between flexible and rigid panels. Kyocera for example warrants their panels for marine use and a minimum of 95% output for 20 years. Some EVA panels are warranted at 90% from year 1 and at only 80% output starting at year 10, the Kyocera's are warranted at 95% output at year 20, and they've actually been around longer than their warranties have been in place...
Amorphous Panels - Amorphous panels are made differently and by their nature require nearly double the surface are to equal the same watts in a mono or polycrystalline panel. They are upwards of 50% less efficient than a good mono or polycrystalline panel.
In the marine space many of these panels are made to be flexible which can make them even less efficient. The combination of a flexible EVA lens, that can slowly degrade in UV, and the fact that one side may not be aimed at the sun if "flexed", say over a boom, can often mean very little output for the sq in you have out there. Even in perfect conditions you still need a lot more space for an amorphous panel than you would a mono or polycrystalline panel. Yes they can be convenient but you need to weigh the benefit/space/cost & efficiency issues too.
While there are some high efficiency flexible panels that are not amorphous, such as the Solbien's made in Italy, that compare in output to the rigid panels, they are quite costly compared to rigid panel at nearly triple the cost or more. Ganz also makes some efficient smaller panels but again the price is about double or more what a rigid panel costs. If that convenience is worth it, then they are a good deal.
The neat thing about the Solbien panels is that they can be sewn right into a bimini top and have no sharp edges. Some of the solo round the world racers are using this technology and, good for us, it will eventually trickle down. Due to the flexible nature however they will probably suffer from UV degradation faster than a comparable glass encapsulated panel.
Amorphous panels do have one benefit and that is they are less prone to shading issues than a mono or polycrystalline panel this benefit however can be quickly dwarfed by the real estate needed to equal the output of a rigid panel..
Wiring:
The wiring of your panel to the boats battery bank is critically important. Most decent 12V panels will output a voltage of around 16.0 to 18.5 volts +/-. Giving up any of this voltage to voltage drop can affect how quickly your bank is recharged. If you're using an MPPT controller voltage drop should be almost nothing to maximize performance. I like to size panel wiring for a 1-2% voltage drop max.
Controller:
Any panel sized to actually "recharge" your bank will need a solar controller. There are vast quality ranges amongst controllers and a bad controller can be a complete waste of money and wreck the efficiency of your system.
There are essentially three types of controllers;
MPPT = Multi-Point Power Tracking - These controllers take excess voltage and turn it into current rather than wasting it. When you consider most 12V panels will supply a voltage in the 18V range, and that your battery bank really should not be charged in excess of 14.6V or so, that can leave wasted and unused energy potential. The idea and concept of an MPPT controller is that it takes any excess voltage and converts it to charging current. It is more complicated that that but in a nut-shell that is what they do.
Most MPPT controllers will work best when your array gets over 150-180 watts in size and you really do have "excess voltage".. The Genasun MPPT controllers are specifically engineered for small panels below 150W and are the only MPPT controllers I know of specifically designed as such. They extract the max current they can out of small panels.
PWM = Pulse Width Modulated - These are the best alternative to an MPPT and they charge quite efficiently but can not turn excess voltage into current.
Shunting Controllers = These controllers shunt or switch the panel current/voltage OFF when a preset voltage is reached and then turns back on when the battery bank voltage drops to a second preset ON voltage. These are the least desirable controllers and are best avoided. If a controller does not specifically say PWM or MPPT is is probably a cheap shunting controller. I do not advise spending your hard earned money on shunting controllers for sailboats.
Why?
These devices begin switching on/off once the bank hits absorption voltage and can really cut your time to full by days, not minutes.
In the case of some of the Sunforce controllers, often sold at West Marine, they switch OFF at around 14.2 volts and they do not switch back on again until 13.0V. This may be fine for an "off grid" application where you often have a load that sucks the bank back to 13.0V very quickly, but, with a boat on a mooring, with no loads, it can take a healthy bank a LONG time to drop the surface charge back to 13.0V.
I have some customers with banks of AGM & deep cycle wet cells batteries that will sit at over 13.0V for well over an hour, and this is at 70F. When colder they hold the voltage higher for even longer. That is an hour of lost charging time waiting for a cheap shunting controller to switch back on and provide maybe 60 seconds of charging before raising the bank to 14.2V and then shutting off again. Sometimes these cheap controllers will never restore the bank to full, no matter how big the array, in the time you need them to.
Below is a video of one of the "better quality" shunting controllers, a Flex Charge PV-7. It shuts OFF at about 14.4v and does not come back on until the bank voltage has dropped to about 13.6V. The first video is showing the "current" but you can see it turn on and off. I applied a load of 0.1A just so it would go to -0.1A when OFF for the video. When you get close to full your OFF time can be as much as 10-20+ times longer than your on time with some cheap controllers.
The second video is showing the voltage behavior.
In this case the "ON" time is about 5-6 seconds and the OFF time close to a minute to get the bank back down to 13.6v before it can turn back on again. This bank still had 20 Ah's to go and it would take 5-7+ days for this bank to eventually get "full" from an 80-85% state of charge with 5-6 seconds on and 60 seconds off, remove the 0.1A load and it would likely make this even longer..
It should be noted that before I took these videos the banks were charged to full using a shore charger until they were accepting less than .5% of C (capacity) at 13.6 volts. At this point, after being on float for two days, the battery monitor was re-calibrated manually to read "full". I then applied loads and removed approx 30 Ah's from the bank. The solar re-charge time was then monitored and the time it took to replace the 30Ah's removed calculated.
Contrast that Flex Charge controller, or a Sunforce, with a quality PWM or MPPT like the Genasun MPPT or a Morningstar Pro-Star 15 PWM controller and the difference in the last 15% of charge, and the time it takes, can be quite dramatic.
I recently replaced both a Sunforce and a Flex Charge shunting controller with Genasun MPPT controllers. On one boat "FULL" was cut from averaging 7-8 days to about 2 days and on the other boat "FULL" was cut from roughly 5-6 days to about 1.5 days. Same boat, panels, wiring, batteries, just a much better quality controller that does not turn ON/OFF like a cheap shunter will. A lot of the controllers you buy from "discount" solar houses & eBay sellers are "shunters"...
If you stick with Morningstar PWM, starting at the Pro-Star series, Blue Sky, Genasun and a couple other reputable controller manufacturers, you'll be doing well. I've found the eBay stuff is very often a scam, so be careful. There are surely other quality manufacturers out there but Blue Sky, Genasun, Morningstar & Outback are among the most respected and widely used.
I have replaced a number of eBay, so called, MPPT controllers that were not MPPT at all but rather simple shunting controllers. MPPT & PWM controllers do not shut off for long periods of time like shunters do.
The Genasun MPPT's are a very good value for smaller for panels. Under 150W, that is pretty much all I am installing these days, unless I have a bigger array, and then I'll use Blue Sky or Morningstar.
Please be careful with "cheap" controllers as you often get what you pay for.
I generally buy from Northern Arizona Wind-Sun, Wholesale Solar, eMarine and a few others. I pay a little more but I know the quality is good and they hold up in the marine environment.
Connecting It To The Boat:
A solar panel sized to re-charge should ideally be routed directly to the house bank. You can then use a device like an Echo Charger to send a small charge over to the start bank to keep it topped up. Even without a solar panel an Echo Charger is a tremendous device. It should go without saying that anything connected directly to a battery bank should be fused.
Sizing:
How do you size this? At a minimum a 1.0A to 3.5A panel can be okay depending upon the size of your bank and depending upon which charge controller you use. You can easily go beyond 15A with solar but you need some real estate to devote to it.
Ideally you want the alternator to bring the bank back to 80-85% state of charge and then let the solar panel do the rest, when you're not there during the week. If you want to satisfy cruising needs such as refrigeration, instruments, AP etc. then your array will get quite large.
The faster you can bring the bank from 80% to 100% the less sulfation you will have and the longer battery life you'll get.
For a sizing example, lets look at a bank of 300 Ah's for "mooring recharge".
With simple math you can see that the last 20% of capacity is 60 Ah's. However you need to take charge inefficiencies into account too so you'll really need to put back in about 70Ah's +/- to get back to 100% state of charge.
For sailboats the panels are usually left flat when your not there so that you can capture "most" of the sun. In a land based installation the panels are fixed, the property is not moving like a boat does, and can be angled at the sun. This is not so on a boat, so panel position is very often a compromise. If you are at a dock you can rig the panels and aim them more appropriately but not on a mooring or off cruising where your boat will swing at will.
Because of this you can figure on about 4 - 4.5 hours of full output per day on average, for the Northern climates, and 5-6 hours per day the closer to the equator you get.
Some folks use 5 hours per day in the Northeast I found that to be a little to generous.. Some days it will be more some less but here in Maine 4 - 4.5 hours at full output works best.
So, a 300 Ah bank @ 20% down = 60 Ah's that need to be returned + charge inefficiency = 70 Ah's total needed for "full"
A 2.5A output panel X 4.5 hours = 12.5 Ah's/Day returned to the bank. If you have phantom loads, like a propane sniffer or other "always on loads, subtract those and that is your "net".
Next divide 70 Ah's by 12.5 and you can see that it will take approximately 5.6 days to go from 80% SOC to full on a 300 Ah bank.
That's a little long so a panel in the 3.5A output range or more would be better served. A 3.5A panel shaves a full day off the time it takes to hit full..
Shading (The Big Bad "S" Word!)
The biggest performance killer in marine solar is SHADING! You need to keep the panel out of as much shade as you can. Under the boom often seems ok, convenience wise, but your charging performance will get murdered. Even small amounts of shading can cut the panels performance by 50% - 80% depending upon the severity of the shading.
I moved one customers 40W panel from under his boom, just in front of the dodger, to his stern push pit and he went from never getting his bank to full to getting back to full in about three days. Same panel, controller and boat just eliminated about 90% of his shading issues.
Best Locations:
Bimini Top
Davits
Pole Mounted
Movable & Positioned At The Sun
Worst Locations:
Boom
Under Boom
On Deck
Dodger Top
One of the easiest locations for small panel installs is right of the stern push pit, if you do not have a bimini. If you have a bimini mounting it to the top of the bimini frame is a great location.
To mount them to a push pit I use standard dodger fittings. Do not drill the second hole until you've "fitted" it to the stern rail and marked where the angle needs to be:
This was a small 30 watt / 1.8A unit for a 200Ah bank.
For the backs of the fittings I use a decent sized fender washer and nyloc nuts. I will often put TefGel on the mating surfaces to the aluminum.
For the outer edge support strut I use what I call a flip-flop hinged deck fitting. These are not inexpensive, about $36.00, but they work really well in this application.
As you can see the tube eye simple bolts to the hinged deck fitting:
To mount everything to the stern push pit I use three "split jaws". Again, not in-expensive, but perfect for this application and it keeps the sharp edges of the panel out of the cockpit.
For stainless to stainless always use Tef-Gel to prevent thread galling:
The finished installation takes between 2 and 5 hours to mount and wire up depending upon interior access etc.:
The wiring to the battery bank could not be easier. From Panel + & - and To Battery + & -. When wiring the controller to a parallel or series/parallel bank always wire your positive and negatives "across" the bank meaning neg at one end and pos on the other end. The controller should also be mounted as close to the bank as possible.
