Too much solar on this arch?

[Ryban]

I'm mocking up an arch to mount a few panels up above the transom, straddling our backstay, and attached to the boomkin/pulpit.

This is in no way an final design, but it gets the idea across.

My original plan was to "just" have 2x 200W bifacial panels here. These are about 28lbs each. But.... it is very tempting to create a sliding setup, where 2 additional panels can slide out from underneath the panels when anchored, or sailing in calm conditions. My only hesitation is that this would be a total of 28x4 = 112lbs of just solar panels, not accounting for any hardware to make the system work. It seems like maybe a lot of weight to be mounting at this location but I'm curious to what you guys have to say.

I didn't model them, but I'll be adding braces that go between the pulpit and the boom gallows as well. The boomkin and gallows are extremely strong. The pulpit is solid, but is currently held in by fasteners so will likely need to be welded.

[SailingHarmonie]

I know power consumption always expands to just a bit more than power available, but…

Are you sure you need that much solar? Really? I sail a 53 foot Amel, with two large freezers, and a refrigerator, and a lot of electric users in addition to that. 1300 W of solar makes all the power I need, (about 6 kWh/day) almost all the time. It’s hard to imagine how you can consume that much power on a Westsail 32.

[Jimbo2010]

I don't like how high they are, try lower like below the boom, yes you'll have some shade , but there are ways to minimize the effect.

When heeled your going to have them catching a lot of air

Also the cost to build a set monkey bars will be $$$$

Lastly not very attractive

[malbert73]

That’s a W32 right? Not known for upwind performance as is, and you’ll certainly ensure that with that much windage. Some good analyses on Morgan’s Cloud (behind paywall) which indicate just how much a solar farm can affect performance

[Ryban]

This is why I ask! So people can rationally talk me out of it.

Predicted solar requirements:
I've done a lot of math on what our power requirements will be based on my own cruising experience and our needs for this trip. A couple of things that will increase our loads are potentially adding an induction cooktop (~600-1200Wh/day), an electric outboard (maybe ~400Wh/day), and a Rainman watermaker (12V version, maybe 200Wh/day -- averaged out over the week). The Rainman uses a standard high pressure pump, rather than an energy recovery pump, and so is at least 3 times less efficient than a Spectra, but is much cheaper upfront, and cheaper/easier to repair.

Assuming 80% panel efficiency, and 6 peak sun hours a day, we'd probably squeeze by with 550-600W total, but 750W would be better.

Slide Out Panels:
That said, I think slide-out panels is dead to me for my boat at this point. It's just too much back there. Maybe we'll keep some compact panels down below that we can deploy safely off the lifelines while anchored.

2 Panels on the solar arch
Not yet killing the solar arch entirely. The reason I drew it the way I did was to keep it high enough that you could stand at the transom without ducking, and also prevent the panels from blocking air flow to the windvane (not shown). It probably could come down a foot though.


Other options
There aren't a lot of other good options for mounting solar on Westsails. One option we are also considering is strengthing our dodger, possibly converting it to a hard-top, and adding 3x ~100W panels there. We could also add 100W to the "garage box" in front of the dodger, but this is also where we currently plan to stow our nesting dinghy. We can also hang 2x 100-150W aft of the larger 175W that are currently on the boat, and these would be supported between the gallows and pulpit.

All these options are seriously impacted by shading considerations though. For the panels on the sides, one side is likely to be shaded partially by the hardware around them, which includes the boom, the rigging, the boom gallows, and the wind vane. For the panels on the dodger, obviously the boom will be problematic except for when it can be moved out of the way.

As drawn below, very roughly sizing the panels, there's a total of 850W, and 650W if we exclude the aft hanging panels. Realistically we'll probably only see 70% of this value given shading and other factors.

[Jimbo2010]

U may want to downgrade some of your needs, for example induction cooktop, nice plugged into a dock

You simply don't have the room on a 32' boat

[Ryban]

We're keeping our propane stove/oven, but it would be nice to have the option to use the extra juice we're getting to cook meals too, with a single-burner portable induction burner.

I think our needs are reasonable. Might only 32 foot boat, but it's also about the fattest/heaviest 32 foot boat out there.

I think people tend to underestimate their power requirements, and make up for it by running their engine or generator frequently, which we have no desire to do.

[bergius]

Originally Posted by Ryban

]
That said, I think slide-out panels is dead to me for my boat at this point. It's just too much back there. Maybe we'll keep some compact panels down below that we can deploy safely off the lifelines while anchored.

Our Amigo 40 (31ft) is a quite similarly sized double ender as your W32. We ended up with a smallish solar arch that carries two 120W panels. We have also a third 120W panel on the cabin top, but that gets shaded by the boom in most circumstances.



I’d love to have a bit more solar capacity on the arch, but it is hard to build with our stern shape.

What helps, is the 300W of deployable panels that we can pull up the mast when anchored.



With the combination (and our hydrogenerator), we’re more or less independent on electricity during the northern summer at the Baltic Sea. Though admittedly we don’t have electric cooking. And now that we added Starlink I don’t think we have the energy budget to keep it running 24/7.

But yeah, I’d recommend keeping the arch, maybe slightly downscaled. And then plan for as much deployable capacity as you can. Panels on the spray hood or cabin top won’t contribute much (but every little bit helps).

I love the CAD models, BTW!

[abroadreachtrvl]

I like the arch but I would think about moving them down and farther aft. Possibly integrate with the gallows?

Don't give up on the slideouts too quickly it's a good way to maximize wattage while limiting windage and size when needed. We had one on the old boat and designing one for the current boat. Many have had success with industrial SS drawer slides from McMaster Carr.

[malbert73]

Originally Posted by Ryban

We're keeping our propane stove/oven, but it would be nice to have the option to use the extra juice we're getting to cook meals too, with a single-burner portable induction burner.

I think our needs are reasonable. Might only 32 foot boat, but it's also about the fattest/heaviest 32 foot boat out there.

I think people tend to underestimate their power requirements, and make up for it by running their engine or generator frequently, which we have no desire to do.

I look at it the opposite. My Tartan 40 sails much better in light air than the W32 but yet we end up motoring or motorsailing a lot in coastal cruising as no boat sails in a calm. The 100+ amps we put in are free power when entering/leaving harbor, and motorsailing when needed.

Otherwise, we can run our genset- and simultaneously bulk charge batteries, make hot water, and use our Rainman with 120v AC motor to make water. All of that in 1 hour of genset which generates 3-5KW depending on usage. way more solar than we could install on our somewhat streamlined smallish 40 footer. So, solar is a nice adjunct but we’re just not willing to add more solar than a normal sized canvas bimini can sustain. I think you need to consider the W32 as too small to power with that much solar from an aesthetic and seamanship perspective. That windage will not only slow you down and look huge, but could affect trim and weather helm

[Don C L]

That’s a lot of surface area added up high, especially in 30 or 40 or more knots. It will tend to kick the stern around ( weather helm.) Too bad there is no way to fold them up when the wind pipes up.

[Jimbo2010]

Agree, bad idea

Originally Posted by malbert73

I look at it the opposite. My Tartan 40 sails much better in light air than the W32 but yet we end up motoring or motorsailing a lot in coastal cruising as no boat sails in a calm. The 100+ amps we put in are free power when entering/leaving harbor, and motorsailing when needed.

Otherwise, we can run our genset- and simultaneously bulk charge batteries, make hot water, and use our Rainman with 120v AC motor to make water. All of that in 1 hour of genset which generates 3-5KW depending on usage. way more solar than we could install on our somewhat streamlined smallish 40 footer. So, solar is a nice adjunct but we’re just not willing to add more solar than a normal sized canvas bimini can sustain. I think you need to consider the W32 as too small to power with that much solar from an aesthetic and seamanship perspective. That windage will not only slow you down and look huge, but could affect trim and weather helm

[Ryban]

Yea it’s pretty much dead to me at this point. That said, I had an arch on my Albin Vega that carried a 200W panel, and the boat sailed fine.

As far as running the engine regularly as part of our travels, I think it depends on the type of cruising. There are plenty of places I dropped the hook where I didn’t have any reason to run the engine for weeks at a time, and so having the solar capacity is nice form of clean, free, virtually maintenance free energy. There were also places I spent months where diesel wasn’t available, and conserving what we had was important.

[malbert73]

Originally Posted by Ryban

Yea it’s pretty much dead to me at this point. That said, I had an arch on my Albin Vega that carried a 200W panel, and the boat sailed fine.

As far as running the engine regularly as part of our travels, I think it depends on the type of cruising. There are plenty of places I dropped the hook where I didn’t have any reason to run the engine for weeks at a time, and so having the solar capacity is nice form of clean, free, virtually maintenance free energy. There were also places I spent months where diesel wasn’t available, and conserving what we had was important.

There are quite a few origami type solar panel options perhaps you could store below decks and deploy for the intermittent use cases?

[quartersplash]

Could you post a few more photos of your arch? I am considering the same on my Nor'sea 27. Thanks

Originally Posted by bergius

Our Amigo 40 (31ft) is a quite similarly sized double ender as your W32. We ended up with a smallish solar arch that carries two 120W panels. We have also a third 120W panel on the cabin top, but that gets shaded by the boom in most circumstances.



I’d love to have a bit more solar capacity on the arch, but it is hard to build with our stern shape.

What helps, is the 300W of deployable panels that we can pull up the mast when anchored.



With the combination (and our hydrogenerator), we’re more or less independent on electricity during the northern summer at the Baltic Sea. Though admittedly we don’t have electric cooking. And now that we added Starlink I don’t think we have the energy budget to keep it running 24/7.

But yeah, I’d recommend keeping the arch, maybe slightly downscaled. And then plan for as much deployable capacity as you can. Panels on the spray hood or cabin top won’t contribute much (but every little bit helps).

I love the CAD models, BTW!