Tilting solar rack - 2 ways?

I'd like to try winter sailing this winter. In order to do so, I need a lot of solar that can be tilted towards the sun. As a boat tend to not have the same side towards the sun at all times, the mount has to be able to tilt to both sides. (I don't see tilting forward/backward as an option, cause the panels will make shade to each other.)

I've lived in a off grid house for the past 4 winters and learned that both vertical and horizontal solar panels is essential. On cloudy December days the horizontal mounted panels produce enough to run household essentials, while vertical mounted provides 0. While on sunny December days, the horizontal mounted panels gives barely more than the household essentials, while the nearly vertical panels gives enough to run washing machine and other high consumers - even hotwater if there is more than 3 sunny days a week. On snowy days the vertical panels provides some charging while the horizontal is covered in snow and provides 0.
Some would argue that larger battery bank would compensate for those low production days, but last winter I had only one sunny day between November 20th to January 2nd. That would require a huge battery bank. The fact that the solar is able to charge the daily essentials, makes it possible for the battery to provide occasional use of a high power consumer.

The thing with a boat (compared to a house) is that weather and sail may require the panels to be put horizontal, while the low winter sun requires panels to be nearly vertical. On the house there is room for vertical panels on the wall, while horizontal panels are on the (almost flat) roof. A boat doesn't have room for both. Hence there is a need for adjustable tilt. I'm planning on building a hard bimini to put solar onto, and also put solar in front of the dodger.
Also with a boat it doesn't always have the same side towards the sun, hence it would be nice to be able to tilt to both sides. Has anyone seen any mounting racks that is able to tilt to both sides? Ot have any ideas how to make such?

 

A boat doesn't just change course, but also heels and pitches. You will have to make some compromises compared to the comfort of living in a house. You could have racks that tilt in any direction, but you will spend all your time adjusting them. Also, they are a complicated system likely to fail at sea. I think a bigger concern is ice buildup which would make the boat top heavy and maybe capsize it.

 

An MPPT will get you further ahead than tilting.
However, a combination set-up may prove worthwhile.

How many panels of what size are you considering?
What type of battery?

 

Is A Solar Tracking System Worth It? https://www.energysage.com/business-solutions/solar-trackers-everything-need-know/#active-manual-and-passive-solar-trackers

It might be possible to hack/modify a ground-based tracking system, so that it works from all angles, but there is the disadvantage of additional weight and complexity. Some of the stored power could be used for heating the panels during hopefully short periods when de-icing is required. A backup system to somehow lower the panels might be required if there are prolonged periods of high winds or failure of the de- icing system. What could possibly go wrong, with such a complex system , ha!

 

If you have a sailboat, install a water generator. It is simpler and cheaper. Also, adapt your lifestyle to realities of cruising a small boat.

 

Atilan, I don't know the size of the boat or panels you will be mounting. I agree that optimizing the charge controller to MPPT is a good place to start. Also adapting to what is practical!

James Baldwin's site has a design for small, simple adjustable solar mounts:
The Atom Solar Tracker | Atom Voyages https://atomvoyages.com/the-atom-solar-tracker/

I lived aboard and cruised for many years and had a small PV array (400 watts), adjustable along a single horizontal axis. This seemed to strike a balance in between simplicity and some ability to adjust. In the winter months, I was often parked in marinas for longer periods. Finding a N/S oriented slip and tilting the panels once a season was enough for me.

 

As a few others have stated, go with an MPPT charger and be sure to wire the panels together in series to feed the charger as much voltage as it can handle,

A Victron charger for example will wake up and start a new charge cycle as soon as panel voltage exceeds battery bank voltage by 5V, so the higher the voltage output the sooner your daily charge cycle begins and the longer it will last, and this really helps when you consider morning sun is what replenishes your draw from the night before, and late sun helps to top off your bank before sunset.

Combine that with some sort of tilting/tracking so you can set the panel up toward sunrise and sunset to maximize harvesting, and you will reap the benefits.

I wouldn’t bother with linear actuated tracking, just a simple mechanical tilt/lock feature for sunrise/set adjustments.

Mounting hardware-wise, the stainless rail fittings and tubing that are commonly used on boats (as shown in above posts photo) can be used to fabricate a support for solar. For adjustability, take a look at the mounts made for Radio Antennae which allow for articulation for stowing during trailering and in rough conditions. Some clamp on to standard rail tubing providing 2 axis adjustability.

 

@qonzo
Panels has to be down while sailing. Panel can be up when boat is not moving, maybe also when motoring with no wind.

@BlueBell
I have no experience in not using MPPT. More importantly is how the MPPT algoritm is implemented. When my main MPPT charger gives less than 200w, I can jump my panels over to the spare MPPT charger, and get 500w of charge! (Reason for not using the spare as primary charger is communication with the inverter and adjust charging depending of inverter load.)
I managed to kill my spare charger last October. The result was that I had to run generator every few days cause there were not enough sun for the primary charger to charge anything at all. With the new spare charger in place, I didn't need to run generator all december, even when there wasn't any sign of blue sky all month. MPPT is not just MPPT. It's a huge difference in how MPPT works!

I have 18x270w panels + 2x100w on hand. I'll fit as many that I manage. It all depends on how I end up designing the bimini. Maybe include a hard dodger. Maybe have a foldable wing that extends behind the stern. I don't know yet. It also depends on how the panel mounts look like in the end.

@portacruise
Solar tracking is good if you have space. Problem with such on a boat is that you don't have the space to put the panels far apart - they will end up making shadows to each other. I can't imagine any way to have panels facing forward/backward without making shadows to the next panel - except for a wing at the stern - it could be wing up or wing down without shading the others. Tilting to the sides however could be possible without making shades. However the mechanics for this may become too complicated to be worth it. Thats why I started this thread, hoping for someone to show some genius ideas.

@qonzo
I have water generator. It's doesn't do much while at anchor, which is where a cruise spends most of his time. However at sail, when the solar panels is folded down, it's a nice addition.

@jmwoodriq
I guess you had sunny winter days if 400w panels were giving charge in winter.

I got a two ideas. Not sure if any is doable.
1) My boom is near 6m long, and it can swing. If solar panels could hang on the boom when sail is down, it should be possible to have 5 panels there. Then the boom could be set to a suitable angle to catch sun. This idea requires some mounting system that allows the panels to be put down on deck when sailing. Don't know how that could be done.
2) Hoist a column of panels up the mast when not sailing. 4-5 panels could be possible, but they need to be held in place. Maybe they could slide on a track at front of the mast? There they could possible rotate to each side. This requires some way to stack the panels at deck when sailing. These panels will not be able to be contribute when horizontal position is needed. But would be good when vertical is needed. Downside is that they will make shadow over all the other panels if boat is bow towards the sun.

Other idea is wings on both sides of the bimini. Tilt down on one side, up on the other for facing the sun on either side, without shading for any panels that is horizontal on the bimini. When sailing, or at anchor in strong wind, these wings could flip over and lay down on the bimin - on top of those that a fixed there. But when laying there, not only are the wings hiding the panels that are fixed there, but them self are even upside down.

 

And what kind of battery are you using?

 

How often will the tilting be adjusted, and will it be for each individual solar panel? Instead of adjusting the individual solar panels while at rest, can they be mounted in such a way that constantly adjusting the sun angle rotation of the boat itself gives better output because of the impractibility of constantly having to manually adjust the tilt and rotation of individual panels ( like Atom @ say 2 hrs)? Maybe the angle of the boat at drift/ rest can somehow be adjusted with very small low drain Maybe GPS lock motors (automated?) so that the closest possible to 90° Sun angle of rotation is always presented, while at rest? Or maybe use two anchors. Or stake out poles in the shallows, Periodically adjusted to roughly hold a good sun angle? Motors are kind of a niche application, as they won't work in Marinas, if the motor drain is too high, or in many other situations, sorry if these ideas don't help with what you are trying to do.

 

I've considered the idea of a gimballed panel on a transom arch. As the boat heels, the panel stays pointing up. It won't maximize the angle towards the Sun, without septate adjustment, but it should give the best general solution with minimal work and tech.

 

@portacruise
How often they'll be adjusted depends on the weather. If cloudy or windy, they will be horizontal, just as sailing. If not cloudy, not windy, not sailing they'll be up.

@Will Gilmore
I don't think gimballed panel serves much purpose, unless your boat spends most of its time tacking. It would make a lot of ware on the fittings. Besides I don't see how a gimballed mount could handle more than 2-4 panels.