Solar Installation on 37 Pilot House

We are considering a solar installation to keep the house batteries up while at anchor without the generator running periodically. Most of the pictures of the installations I can find look like the panels were installed on the pilot house roof, a panel either side of the hatch, although I have seen some boats mount them on or above the Bimini. I would be interested to know what others have done; mounting locations for the panels, total wattage of the panels, and do you feel it is / was worth while. Based on my calculations I think we need 600-800watts to hold the house loads and top off the house batteries on a daily basis assuming the sun is shining. Our two biggest house loads are the refrigerator and Starlink when it is running. Thanks in advance.

Different boat, but same basic idea. I have a raised pilothouse and have two 385 watt panels up there.
Huge difference. I still run at a deficit, but I can easily last three or more days before having to start an engine.
My main draws are the same as yours, but also add in microwave and coffee maker usage. Inverter is on 24/7 too.

I have a single 365W panel on the PH roof. It is what would fit. I have a collapsible Bimini over the flybridge and it would be much better if I replaced it with two large permanently mounted panels. I just didn't want to do that much work. Others have mounted panels on their deck rails, often on hinges, to give them more usable solar. This also works well, but not something I wanted to do as they would interfere with the kayaks and SUP boards that are hung there. My 365W panel has been enough to get my 780Ah AGM bank to full SOC during the summer after running the genset in the morning to get the bank from Bulk to absorb. For me it has been well worth the cost and effort and it is only 365W.

My thoughts are that some solar is great, more solar is better, and more solar is rarely "enough" solar. There are some that have been able to fully replace their daily Ah budget with solar, but it takes a big solar commitment in cost and real estate to accomplish it.

I have future plans for panels on our pilothouse roof. Same boat, so very similar issues.

That said, I heard a perspective that resonated with me. Diesel is cheap. The author said he can "replace the amp hours used in a day or two with a generator run for a couple dollars an hour and not fiddle with solar. And panels don't last much longer than batteries." Interesting. It has me thinking.

HeadedToTexas said:

I heard a perspective that resonated with me. Diesel is cheap. The author said he can "replace the amp hours used in a day or two with a generator run for a couple dollars an hour and not fiddle with solar. And panels don't last much longer than batteries." Interesting. It has me thinking.

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Everyone has to make their own decision based on how they use their boat, but I don't know anyone who has installed solar and got rid of it in favor of running their generator.

I figure the all-in costs of running my 6kw northern lights generator is roughly $10/hour. With that I can produce roughly 2kwh-3kwh of energy, about a days worth of my solar 800w panels.

Whether 800w is enough depends on a lot of different variables. Size of boat, how and where it's used, etc. What is undeniable is 800w of panels will out a helluva dent in your consumption. Depending on your latitude and season, 800w will produce 4/kwh/day. Nothing to sneeze at.

Peter

I have run solar on our 36 foot trawler for three years now, since first splash as our boat in 2022. Having enough solar wattage allows me to dock without having the added expenses of shore power. The real benefit for me is being on the hook for more than two weeks at a time and never having to run a genset at all. We have a medium size 12V fridge that runs off solar full time, and our two kilowatt inverter runs full time, mostly running house lights, TV's and computers. Of course, we're not able to run a coffee maker at the moment. (Our current coffee maker is a kettle boiling on our propane stove).


I do intend to add more power, as this year we experimented with a wind turbine, and found that its output is quite meager compared to a single solar panel on a cloudy day. Currently I have two 200 Watt panels, which are mounted to the rear of my Europa flybridge deck. I intend to add two more panels on the rear port and starboard rails, with a fold down mechanism. This summer, we were at a National Park dock one day, and ran into a Quebecker who had done the same thing. His novel clamping and fold up/down clamp was 3D printed. I thought that was kind of cool. I am also planning to add a third lithium battery to my house bank which currently runs lead-lithium. This is so we can have that much-desired electric coffee-maker running daily . It seems to work for us. At our current power needs. Anyway your mileage may vary depending on your power consumption needs.

We have 600 watts between the pilothouse and hardtop. If the sun shines we do not need the generator to keep the batteries charged. They are generally fully charged by 11:00 am every day. We have a 110 volt Summit refrigerator and run a electric coffee maker in the morning. Cooking is propane.

We only run the generator at anchor if we need hot water. I really should investigate a way to use the excess solar to heat the water.

When at our home dock we do not plug in unless we want AC.

Rob

I have 3.2 Kwp on my boat. 2000 Wp on a frame above the stern and on the dinghy deck, the other 1200 Wp is hanging on the side of the boat and I need to fold them up.
I have 1400 Ah of 24 V in lithium and during the summer, with all panels out I am able to recharge the batteries every day, however I still need to be careful how to discharge the batteries. Usually by 2 PM the batteries are full again, so then I run all the heavy equipment (washing machine, dish washer, water maker, boiler etc), which means by night I only need to cook, have the lights on and perhaps TV.
Now in autumn I cannot have the side panels extended, the frequent storms make that impossible, so I only have the 2000 Wp available and with diminished sun light I cannot recharge the batteries completely.
Luckily the alternators can finish the job when the engines are running, but when we stay in an anchorage for e.g. 1 week we need to run the generator every now and then to recharge the batteries.
Below the 2 options I have, first picture is with the side panels folded down and the second picture is with all the panels extended.
During summer, with all the panels extended, I normally get to about 2400 - 2600 W per hour, which is pretty good I think.

mvweebles said:

Everyone has to make their own decision based on how they use their boat, but I don't know anyone who has installed solar and got rid of it in favor of running their generator.

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I'm sure I would be in that group too. Like many things, including generators, they're great when they work well. Solar panels don't work forever, but probably plenty long enough for most (and at 0.5-0.8% loss per year, plenty long enough for me). Generators don't last forever either and cost a lot more to replace.

My read on the "diesel is cheap" opinion is that the guy found running his generator easy and deciding about, buying, configuring, installing, and managing a solar array difficult. It's not my opinion, but I see some logic in it.

2-225W “Marine Grade” panels installed. If I mounted them further aft another panel could have been mounted forward of the roof hatch for a total of 675 watts.
I run the generator 1 1/2 hrs morning & 1 1/2 hrs at bed time.

Loads are stock reefer freezer , large Dometic chest freezer 12v/120v, LED lights and Star link. With a 450ah house battery bank. No problems.

Nocanvas said:

I run the generator 1 1/2 hrs morning & 1 1/2 hrs at bed time.

Loads are stock reefer freezer , large Dometic chest freezer 12v/120v, LED lights and Star link. With a 450ah house battery bank. No problems.

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I guess that is the point of the "diesel is cheap" opinion. If you are going to run your generator twice a day anyway, why have solar? We have the same fridge/freezer and LED lights (plus coffee maker and water pump) loads, but no chest freezer or router. Our house bank is slightly bigger at 600 Ah, but we need just one 60 minute generator run per day with no solar. Has me thinking.

I have read advice saying to mount panels so that air flows beneath them for cooling, but I see plenty (most really) mounted directly on the deck. No matter how tight they are to the deck, the Mariner/Helmsman pilothouse roof is arched and the gaps will harbor spiders. Pros and cons of higher or lower mounts?

HeadedToTexas said:

I guess that is the point of the "diesel is cheap" opinion. If you are going to run your generator twice a day anyway, why have solar? We have the same fridge/freezer and LED lights (plus coffee maker and water pump) loads, but no chest freezer or router. Our house bank is slightly bigger at 600 Ah, but we need just one 60 minute generator run per day with no solar. Has me thinking.

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With a lead acid battery, one of the most important ways to keep it healthy is to make sure that you can get back to a 100% SOC. For many batteries, that can mean an Absorb charge phase of several hours at least.

@Nocanvas has a 450Ah battery bank. That isn't very large and he has some significant amp draws with the freezers and Starlink. Assuming he has an AGM, if he stays above 70% SOC (good for long term battery life), he would only have 135Ah of usable. 50% SOC would give him 225Ah of useable energy. Lifeline recommends a 3 hour absorb charge time for a discharge of 30-50%. It takes time in bulk to get to the absorb voltage then 3 hours at that voltage. Most of that that, the generator would be running at a very low load as the current gradually decreases during the absorb cycle. I keep hearing that it isn't good to run the generator at a very low load.

With solar, the generator can be used in the morning to do the bulk charging. Depending on the battery manufacturer, the max charge rate rate for a 450Ah AGM bank would be around 90amps. If the batteries were discharged down to 50%, it could take 1 1/2 hours to just get through the bulk phase. If they were discharged only to 70% SOC then maybe the bulk phase would be only 30 minutes. Once the absorb voltage is reached (and the sun is shining), the genset can be shut down and solar can finish out the absorb charging, getting the batteries to 100% SOC and saving house of generator run time on low load.

Anyway, that was my rational for installing only a modest amount of solar. Reducing low-load generator run-time was well worth the expense and hassle of installing the solar. Now, as I am switching to LiFePO4 batteries, I am not sure how that will change things. Getting the bank back to 100% isn't as critical as with lead acid. So even though the bank will be larger, it may result is less generator time and more Ahs available daily.

Interesting strategy. Your solar essentially handles the extended absorption phase.

I am guilty of trusting the timing of the bulk, absorption, and float phases to my Xantrex SW3000. Among its shortcomings is the lack of any sophisticated state of charge calculations. As with all of us, new batteries are in my future as the current set are from 2019. I figure on making a decision about solar as part of the battery upgrade.

Nocanvas said:

2-225W “Marine Grade” panels installed. If I mounted them further aft another panel could have been mounted forward of the roof hatch for a total of 675 watts.
I run the generator 1 1/2 hrs morning & 1 1/2 hrs at bed time.

Loads are stock reefer freezer , large Dometic chest freezer 12v/120v, LED lights and Star link. With a 450ah house battery bank. No problems.

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3 hours per day running the generator, 30 days per month, 7 months per year at 3 ltr per hour, 1.40 euro per liter diesel ? That would amount to 2646 euro per year, just for electricity. My solar panels have a warranty of 20 years, but let's say they last 10 years, so that would mean 10 x 2646 euro 26.460 euro and that is when I still have to be very careful with what I switch on and what I don't switch on.
Makes it an easy decision for me.

Not yet living aboard, my math is a bit different. I already own the generator, but not the solar panels, the charge controllers, the wiring or the installation.

On a typical weekend in the islands, we run the generator one hour per day for two days. Wind keeps us in the marina half the weekends, so figure four days per month. Our season is only six months. So 2 x 2 x 6 = 24 hours per season. $4 a gallon is a fair average for diesel this year and we burn ½ a gallon per hour, so 24 x ½ x $4 = $48 of diesel per year. Makes it an easy decision for me too. Everyone is different and everything is a compromise, right?

Perhaps the moral of the story is that we need to get out more!

HeadedToTexas said:

Interesting strategy. Your solar essentially handles the extended absorption phase.

I am guilty of trusting the timing of the bulk, absorption, and float phases to my Xantrex SW3000. Among its shortcomings is the lack of any sophisticated state of charge calculations. As with all of us, new batteries are in my future as the current set are from 2019. I figure on making a decision about solar as part of the battery upgrade.

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My Victron MPPT controller and the Orion XS DC-DC controller are great in that you can set a tail current on the absorption phase. This ends the absorption phase when it should end, instead of when we guess it should end.

My Magnasine MS2812 inverter/charger was good when it was built, but it is old technology. I can set the absorb and float voltage, the max charge current, the rebulk voltage and what voltage causes it to come out of standby to refloat. But I can only set the length of time in the absorption phase.

By playing with the settings in the charger and the MPPT controller, you can get the charger to drop out of absorb before the MPPT controller does which lets the solar to the rest of the work. This reduces electrical loads at the dock as well as at anchor.

grnelson98 said:

We are considering a solar installation to keep the house batteries up while at anchor without the generator running periodically. Most of the pictures of the installations I can find look like the panels were installed on the pilot house roof, a panel either side of the hatch, although I have seen some boats mount them on or above the Bimini. I would be interested to know what others have done; mounting locations for the panels, total wattage of the panels, and do you feel it is / was worth while. Based on my calculations I think we need 600-800watts to hold the house loads and top off the house batteries on a daily basis assuming the sun is shining. Our two biggest house loads are the refrigerator and Starlink when it is running. Thanks in advance.

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I have a 2024 Helmsman 38E. I have no generator. I have 3- 250 watt panels on the pilot house roof. I have 5- 200 amphere hour house batteries. I have been extremely pleased with the operation. I even can run my PH air conditioner off the inverter. My engine has a 160 amp alternator. Running the AC on a hot sunny day while under way, the batteries never dropped below 99%. The alternator and solar panels supplied all the power I needed.
Feel free to contact me for more info on my set up.

amxr39 said:

I have a 2024 Helmsman 38E. I have no generator. I have 3- 250 watt panels on the pilot house roof. I have 5- 200 amphere hour house batteries. I have been extremely pleased with the operation. I even can run my PH air conditioner off the inverter. My engine has a 160 amp alternator. Running the AC on a hot sunny day while under way, the batteries never dropped below 99%. The alternator and solar panels supplied all the power I needed.
Feel free to contact me for more info on my set up.

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I would be interested to understand the position of the three panels on the roof of the pilot house. One on either side of the hatch, inside the sidelights, and one across the front? Or are the two either side of the hatch on standoffs so they are above the sidelights?

From the discussion seems like 600-800w array is reasonable for the refrig, Starlink, coffee pot, inverter load, and a little microwave usage, assuming a house battery bank big enough to back it up. Those loads are independent of the boat size, the challenge is finding real estate to put an array that big on the 37/38. We have a full set of curtains on the bimini with outer canvas that can zip over to protect the glass, so you need a little room right in front of the bridge to get up on the pilot house and deal with the outer canvas, which limits the array length on the pilot house. The hatch and sidelights constrain the array width. On our 37 there is a hailer and flood light which is out on the front of the pilot house roof which further constrains the length, without moving those. Seems like 400-500w or so on the roof of the pilot house like Navigator, the rest above the bimini or on the bridge deck rails somehow like Endless Summer. Seems like it needs to be split, at least on our boat, roof of the pilot house and then bimini or rails.

amxr39 said:

Running the AC on a hot sunny day while under way, the batteries never dropped below 99%. The alternator and solar panels supplied all the power I needed.

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Now that is impressive. Are those the factory installed batteries? Very nice.

grnelson98 said:

I would be interested to understand the position of the three panels on the roof of the pilot house. One on either side of the hatch, inside the sidelights, and one across the front? Or are the two either side of the hatch on standoffs so they are above the sidelights?

From the discussion seems like 600-800w array is reasonable for the refrig, Starlink, coffee pot, inverter load, and a little microwave usage, assuming a house battery bank big enough to back it up. Those loads are independent of the boat size, the challenge is finding real estate to put an array that big on the 37/38. We have a full set of curtains on the bimini with outer canvas that can zip over to protect the glass, so you need a little room right in front of the bridge to get up on the pilot house and deal with the outer canvas, which limits the array length on the pilot house. The hatch and sidelights constrain the array width. On our 37 there is a hailer and flood light which is out on the front of the pilot house roof which further constrains the length, without moving those. Seems like 400-500w or so on the roof of the pilot house like Navigator, the rest above the bimini or on the bridge deck rails somehow like Endless Summer. Seems like it needs to be split, at least on our boat, roof of the pilot house and then bimini or rails.

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This is how Helmdman mounted my panels.

grnelson98 said:

I would be interested to understand the position of the three panels on the roof of the pilot house. One on either side of the hatch, inside the sidelights, and one across the front? Or are the two either side of the hatch on standoffs so they are above the sidelights?

From the discussion seems like 600-800w array is reasonable for the refrig, Starlink, coffee pot, inverter load, and a little microwave usage, assuming a house battery bank big enough to back it up. Those loads are independent of the boat size, the challenge is finding real estate to put an array that big on the 37/38. We have a full set of curtains on the bimini with outer canvas that can zip over to protect the glass, so you need a little room right in front of the bridge to get up on the pilot house and deal with the outer canvas, which limits the array length on the pilot house. The hatch and sidelights constrain the array width. On our 37 there is a hailer and flood light which is out on the front of the pilot house roof which further constrains the length, without moving those. Seems like 400-500w or so on the roof of the pilot house like Navigator, the rest above the bimini or on the bridge deck rails somehow like Endless Summer. Seems like it needs to be split, at least on our boat, roof of the pilot house and then bimini or rails.

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One thing to remember, my engine alternator can put out up to 160 amps. Your key is to have adequate storage. My batteries rarely went below 94% overnight on my trip home on the ICW. With the A/C running on a hot day, the alternator was running close to 100 amps and my batteries stayed at 99%. Solar contributed the rest. All boats should have inverter air conditioning nowadays. That would decrease the electrical load substantially.

HeadedToTexas said:

I guess that is the point of the "diesel is cheap" opinion. If you are going to run your generator twice a day anyway, why have solar? We have the same fridge/freezer and LED lights (plus coffee maker and water pump) loads, but no chest freezer or router. Our house bank is slightly bigger at 600 Ah, but we need just one 60 minute generator run per day with no solar. Has me thinking.

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I feel the same way. If you want to cut out generator run time, you need more house bank capacity. I have 1125 ah capacity. Before adding solar, I could last two nights before starting an engine.
With solar, I can recover a big portion of the daily consumption. Sometimes I can recover all of it, but usually I lose about ten percent of my capacity per day. It depends on how liberal we are with microwave and other ac usage in addition to the cloud cover.
But it’s a great feeling to be in a quiet anchorage sipping coffee and watching the batteries charge silently.
In the summer I can go 5-6 days without starting an engine.
I have to remind myself to run the genset to keep it in good working order.

mvweebles said:

What is undeniable is 800w of panels will out a helluva dent in your consumption. Depending on your latitude and season, 800w will produce 4/kwh/day. Nothing to sneeze at.

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Right. My 700w array has produced just over 1,800 kwh in 3 years.

On the 'diesel is cheap' comparison, I think we have consensus here that generators and alternators yield about 10 kwh per gallon of fuel used. By that measure I've replaced about 180 gallons of fuel with my solar so far. The ROI isn't bad.

Accounting for fuel, maintenance, etc. I figure generator power costs somewhere close to $1/kwh for us. Doesn't take long for solar to pay for itself at that rate. Plus, having power just silently appear without having to do anything is incredibly convenient even if it doesn't supply all of the power we need at times.

I’ve posted before about my solar setup, but just in case OP hasn’t seen it, I wanted to give them another possibility. My canvas bimini was in need of replacement. Due to the amount of rain and difficulty accessing the bimini top, I had mold/moss growing along with holes starting to develop. Long story short, I determined to replace the bimini with solar panels. I used “bed it tape” and caulk to seal the seams. I now have a bimini with dual purpose that will last (technically) for 20 plus years and is impervious to rot from mold. It was also much cheaper.

HeadedToTexas said:

I guess that is the point of the "diesel is cheap" opinion. If you are going to run your generator twice a day anyway, why have solar? We have the same fridge/freezer and LED lights (plus coffee maker and water pump) loads, but no chest freezer or router. Our house bank is slightly bigger at 600 Ah, but we need just one 60 minute generator run per day with no solar. Has me thinking.

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Why have solar if you're going to run your run your generator twice a day? First things that came to mind for me was Hot Water in the morning & evening for showers & dishes and clean up. Solar during the day for a quiet steady electrical load of refrigeration & entertainment. (AC to cool the boat down if needed)

BougeRV tells me that their surface mount panels lose only 0.38% per degree C. I believe that means the watts from a 200 watt panel at 20º C that heats up to 80º C in the sun drop to 154.4 watts. Here's the math.

200 watts - (0.38% x (80º - 20º)) = 154.4 watts

The upside of surface mount is that no spiders or birds live in the space between the panel and the roof. And mounting is easier in that very little, if any, hardware is needed. Is that enough to warrant the reduction in output as the sun heats the panel?

HeadedToTexas said:

BougeRV tells me that their surface mount panels lose only 0.38% per degree C. I believe that means the watts from a 200 watt panel at 20º C that heats up to 80º C in the sun drop to 154.4 watts. Here's the math.

200 watts - (0.38% x (80º - 20º)) = 154.4 watts

The upside of surface mount is that no spiders or birds live in the space between the panel and the roof. And mounting is easier in that very little, if any, hardware is needed. Is that enough to warrant the reduction in output as the sun heats the panel?

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The YouTube channel "Project Brupeg" installed the BougeRv panels. What I liked about the surface mount panels is that they are designed so you can walk on them.