Hard top Bimini with solar panels

[Mjeinstein]

I have a 63 foot hatteras and want to add solar to power refrigerator and a separate freezer. The fridge is a normal household with a freezer as well. At maximum I would use I believe 2,000 watts per day. Boat is generally in areas with good sun. I would like to turn off my generators when anchored or on a mooring ball. Would expect to put panels on a new hard bimini top. Any help for me to understand all this would be appreciated.

[StuM]

Originally Posted by Mjeinstein

I have a 63 foot hatteras and want to add solar to power refrigerator and a separate freezer. The fridge is a normal household with a freezer as well. At maximum I would use I believe 2,000 watts per day. Boat is generally in areas with good sun. I would like to turn off my generators when anchored or on a mooring ball. Would expect to put panels on a new hard bimini top. Any help for me to understand all this would be appreciated.

Please use correct terminology, it avoids confusion.
Watts are a measure of instantaneous power demand/supply. You don't "use" Watts, you use Watt hours which is a measure of energy.

You probably mean 2000 Watt hours per day.
Which is about 160-170 Amp hours per day at a nominal 12 Volts.

If you are using that much and have lead acid batteries, you should have at least 400 Amp hours of battery capacity and preferably more.

To replace 2000 Watt hours, you will need at least 400 Watts of solar panels (could be a bit more or less depending on where you are sailing and what the climatic conditions are).

However! Is the fridge/freezer all you need to power?

You should do an energy budget taking into account all of your electrical needs (lights, instruments, water pumps etc, etc). For everything electrical/electronic multiply the listed wattage by the number of hours that you think it will operate (i.e 1 x 10 Watt anchor light burning for 12 hours will use 120 Watt hours) and add up all the Watt hours.

I suspect that you will find that you will need considerably more than the above if you want to do without a generator for any length of time.

Once you have done your energy budget come back and we can discuss the other issues involved in solar. (panel configuration, charge controllers etc).

[autumnbreeze27]

My advice:
Put as much solar as you can on your boat.
Buy inexpensive 100w flexible panels, wire them in series of two
connect to multiple inexpensive mppt controllers for redundancy
we have 8x100w panels connected to a single 60amp mppt (4 pairs of panels in series wired in parallel)
in the winter it didn't perform very well, but now that the sun has angled up some we have plenty of power
i would say u want 800w minimum, but more is better, if you are fixed mounting them. if u plan on tracking them to the sun you might get away with less.

[socaldmax]

Do NOT buy 100w flexible panels and mount them on a hard bimini. They don't produce rated power, they get much hotter than a normal panel due to no air flow underneath, thus no cooling and loss of power due to heat. Some of them have been recalled due to a fire hazard and when the owner removed them, saw overheated areas in the fiberglass under them.


The #1 concern for solar panels on a boat is shading. You must mount them as far away from possible shading from booms and rigging as possible. A tiny amount of shading can reduce your solar output to virtually nothing.

The #2 concern is efficiency, since you have limited space, you need the most efficient panels you can afford or find. Smaller 100w panels might be easy to fit, but larger panels in the 280 to 300w+ range are more efficient per square foot.

A technique for maximizing solar harvest is using 1 panel per controller. This way, if any panel gets shaded, the controller can adjust for max. output from that panel while the other panel is also getting MPPT from it's controller. If you connect 2 panels to 1 controller and 1 of them gets shaded, the MPP of the shaded panel might drop to 25v while the MPP of the other panel remains at 29v. There's no way to have 2 different voltages on one cable, so one or the other, or both panels will be at the wrong voltage, depending on what the controller does.


Let's say you have room for 2 x 300w panels on an arch over the stern of your boat and wire each of them to an inexpensive ($100 or less) quality 20A controller. They will take up less total space than 6 x 100w panels due to less border area and less framing in addition to higher efficiency. Each will always produce max. power for those conditions regardless of which one gets shaded by how much. If one dies mid passage, you still have half of your output. If you kept a spare $100 unit in the box, you could replace it underway and still have spent less than the $500 or $600 or more that a 45A or 60A big name brand controller.

You can get Renogy, Victron, Eco-worthy and probably quite a few other controllers all in the roughly $100 range each. If you mount the panels fore-aft, you might get 3 or 4 panels on that arch, for 900 or 1200w of solar power. Those are rated values, you'll see less than that in reality.

[autumnbreeze27]

Originally Posted by socaldmax

Do NOT buy 100w flexible panels and mount them on a hard bimini. They don't produce rated power, they get much hotter than a normal panel due to no air flow underneath, thus no cooling and loss of power due to heat. Some of them have been recalled due to a fire hazard and when the owner removed them, saw overheated areas in the fiberglass under them.


The #1 concern for solar panels on a boat is shading. You must mount them as far away from possible shading from booms and rigging as possible. A tiny amount of shading can reduce your solar output to virtually nothing.

The #2 concern is efficiency, since you have limited space, you need the most efficient panels you can afford or find. Smaller 100w panels might be easy to fit, but larger panels in the 280 to 300w+ range are more efficient per square foot.

A technique for maximizing solar harvest is using 1 panel per controller. This way, if any panel gets shaded, the controller can adjust for max. output from that panel while the other panel is also getting MPPT from it's controller. If you connect 2 panels to 1 controller and 1 of them gets shaded, the MPP of the shaded panel might drop to 25v while the MPP of the other panel remains at 29v. There's no way to have 2 different voltages on one cable, so one or the other, or both panels will be at the wrong voltage, depending on what the controller does.


Let's say you have room for 2 x 300w panels on an arch over the stern of your boat and wire each of them to an inexpensive ($100 or less) quality 20A controller. They will take up less total space than 6 x 100w panels due to less border area and less framing in addition to higher efficiency. Each will always produce max. power for those conditions regardless of which one gets shaded by how much. If one dies mid passage, you still have half of your output. If you kept a spare $100 unit in the box, you could replace it underway and still have spent less than the $500 or $600 or more that a 45A or 60A big name brand controller.

You can get Renogy, Victron, Eco-worthy and probably quite a few other controllers all in the roughly $100 range each. If you mount the panels fore-aft, you might get 3 or 4 panels on that arch, for 900 or 1200w of solar power. Those are rated values, you'll see less than that in reality.

He's on a 63' Hatteras, so avoiding booms and rigging shouldn't be an issue. If he's mounting solar on the bimini, it's over the flybridge, so it's fairly high up. He probably doesn't want to add more weight up there than necessary. Considering the size of a 63' Hatteras bimini, 300W panels would probably be a better choice. It looks like Renogy pulled their flexible panels off the market. 250W Mono panels are $240 and weigh 40lbs each. I'd put as many of those up there as you can make fit cleanly.

Before you get your hard top made, buy your solar panels, and make sure the person fabbing your top designs it so the panels can be bolted to the structure, with allowance for the wiring to be run inside the tubing. Try and keep the weight down because the panels are 40lbs each.

Although with a 63' hatteras you might be shopping for a more high end panel.