Solar on a Tolly

Hello everyone. My Capt and I (I don't think he'd call me Admiral yet...) are looking to buy a Tolly in the next year after we sell our terra-firma property and live aboard. We have seen many blogs about sailboats and solar power, but I'm wondering if any of you have experience with solar on your trawler. How many panels? Pros? Cons?

That is a big question, with lots of ifs, but let me give you some thoughts:

The use of solar and how many panels depends on how you use the boat- What are your daily DC loads. How long do you stay at anchor at one place. Do you have a genset.

A related issue is the size of your house battery bank. Bigger means you can stay at anchor longer without recharging.

Since you are still thinking about buying the Tolly, you probably don't have any real answers to these questions. So I wouldn't worry about it right now. Buy the boat, see what size the batteries are and if it has a generator, then use it for a while and determine your DC needs and what your on the hook time is.

But one thing might impact your choice of boat: Many Tollycraft models don't have any place to put panels- the sport sedan doesn't and others like the sundeck models often have a bimini over the aft deck although some have a hardtop that would work to mount panes, but you couldn't put that many due to shading from the flybridge.

So consider which boat you buy. Tollycraft is only one of many boats on the market.

With moderate DC loads, an efficient refrigerator and no air conditioning requirements, 3-400 watts of panels will keep up with your DC requirements.

But if you have a genset consider solar as something to supplement the generator so you don't have to run it so long each day to keep your batteries up. In that case, 200 watts should be plenty.

David

Chainsandanchors6269 said:

Hello everyone. My Capt and I (I don't think he'd call me Admiral yet...) are looking to buy a Tolly in the next year after we well our terra-firma property and live aboard. We have seen many blogs about sailboats and solar power, but I'm wondering if any of you have experience with solar on your trawler. How many panels? Pros? Cons?

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Welcome!

We have at least one live aboard member here who is able to meet all their power needs with solar. Of course they are in a very sunny location.

As was mentioned, you will be limited by boat design as to the number of panels you can fit.

I just added a single panel as an adjunct to the generator. They idea is to be able to completely charge the batteries over the course of the day. However, we don’t live aboard.

Lots of smart folks here who can offer advice.

Thank you! I've already learned a lot from the forum.

djmarchand said:

With moderate DC loads, an efficient refrigerator and no air conditioning requirements, 3-400 watts of panels will keep up with your DC requirements.

But if you have a genset consider solar as something to supplement the generator so you don't have to run it so long each day to keep your batteries up. In that case, 200 watts should be plenty.

David

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I found this to absolutely be the case. I don't have a good area to put in panels, but with just 100watts, it cut my generator use by at least 30%. This year I have found a way to increase my panels to 200watts. On a sunny day that will provide almost 2/3 of my total power needs for 24hrs.

Ken

Thanks to the most-awesome previous owner, I have 1.4kW on the deckhouse. Runs a full size french-door house fridge 24/7 and all other inverter appliances (coffee maker, range, etc.) with house batteries (1600Ah) back to 100% by 1-2pm each day (full sun).

[Edit] Oh, and BTW, I agree with the previous owner of our system about solar on boats and ROI. There is none. You don't do this to save money, you do it because it is interesting to you, no-fuss convenient, less noise at anchor, etc.

The more the better, however spending money on panels, controllers etc, to only still have to run gen lightly loaded for watermaker etc. can be a big waste of money. So sizing the array can get complicated. It’s kind of an all or nothing. The money might be better spent on fuel and generator upgrade. Depends on boat usage and area.

We have 700 watts and added 1200 more for hurricane season in Grenada, because I got the panels really cheap and the power is 50hz, so spending the rainy, muggy season, it was nice to have A/C in the afternoon running off solar, since marina was not an option. Sold panels afterwards.

Sealife said:

The more the better, however spending money on panels, controllers etc, to only still have to run gen lightly loaded for watermaker etc. can be a big waste of money. So sizing the array can get complicated. It’s kind of an all or nothing. The money might be better spent on fuel and generator upgrade. Depends on boat usage and area.

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I don't necessarily agree that it is an all-or-nothing. I think for some, having enough solar and batteries to be most dino fuel independent for electricity is great. However, for many of us, solar is a perfectly adequate adjunct that simply helps reduce genset run-time and improve long term battery life.

I have a single panel. My hope is that I can get away with running the genset in the morning for an hour to bulk charge the batteries after an overnight draw down, heat water for the day, and make coffee. Then I'm hoping that the solar panel will keep up with the refrigeration, inverter use during the day, and bring the batteries up to float.

So far, with decent PNW weather, I'm able to keep up with both the fridge and a freezer, and handle the overhead of having the inverter on. The batteries get to float every day unless the weather is particularly cloudy and overcast.

I concur with dhays that solar doesn't have to be an all or nothing thing and that it can be complimentary to your other charging sources - how much or how little depends on your own situation. My setup is a house battery bank of 1000 ah, 500 ah usable. I have a 5kw genset and a my engine alternators are 160 amp each. I recently added 2 X 350 watt solar panels and I'm just now getting a feel on how they fit into my regime. The long and short is that on sunny days at 49 degrees north latitude, I'm charging at about 30 amps, giving me 300 ah in 10 hours. This covers my 'hotel' loads (no air conditioning) for 24 hours and float-charges the batteries during the day. In the morning, I see the house bank at about 12.3 volts and I run the genset for about an hour and then cut over to solar. Pre-solar, I would run the genset about 1.5 hours both in the morning and the afternoon.

I'd encourage you to read David Marchand's solar articles in the library section of this site. Another article there by Bob Cofer is also worth reading.

Ok, all or nothing not the best words, but 100 or 200 watts in my opinion is a waste. Anything less than 600 would be a waste for us. Given our loads, batts etc. we would spend $2000 to save an hour on the genset? Wasteful in my opinion given what a gen cost to run including amortization etc.

So maybe “ get enough to make a difference” would have been better. Really depends on use, money could be spent on a bigger battery bank, if they are only out for a few das without running long hours or a marina. Just playing a little devils advocate, as so many people think solar os so great and really don’t look at the numbers.

Sealife said:

Ok, all or nothing not the best words, but 100 or 200 watts in my opinion is a waste. Anything less than 600 would be a waste for us. Given our loads, batts etc. we would spend $2000 to save an hour on the genset? Wasteful in my opinion given what a gen cost to run including amortization etc.

So maybe “ get enough to make a difference” would have been better. Really depends on use, money could be spent on a bigger battery bank, if they are only out for a few das without running long hours or a marina. Just playing a little devils advocate, as so many people think solar os so great and really don’t look at the numbers.

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I think your point is a good one. Unless you can install enough to actually meet your need (whatever that is) it would be pointless. For example, I'm hoping that while away from dock, my batteries can get back to full charge frequently (maybe every day or so) without running my genset for several hours. The benefit really isn't the cost of running the genset for a couple more hours/day but the pleasure of not having the genset run for a couple extra hours/day. There is also the real benefit of keeping the house bank healthy. This is done both by not discharging the batteries as deeply, but also getting them back to full charge. If my install fails in this, it would have been money and effort ill spent.

Even so, it is hard to calculate the real costs of shortened battery life and I invested a full boat buck just in adding 365W of solar. The real reason for me is the enjoyment of the boat when away for a couple of weeks.

There is definitely a case to be made for combining a small/medium size solar panel system with a genset. That is what I have on my boat.

I run the genset for about 45 minutes at night about dinner time to heat water for a shower and charge the batteries, than about 30 minutes in the morning to make coffee, heat up the water for my wife's shower and charge the batteries. I probably put in about 60 AH during that charging period given that I have a 100 amp charger and the batteries are about 70-90% full.

That leaves about 20 AH left to fully charge the 220 AH GC bank. A 100 watt solar panel does this nicely. I would have to run the genset another two hours to get even close to fully charged batteries, such is the nature of LA batteries and chargers.

The solar panel installation cost me less than $200 and was a very worthwhile investment to minimize the noise of the genset running and make sure my batteries get fully charged each day, well each sunny day .

If your power needs are greater and your batteries are bigger, then a 200-300 watt panel system might be indicated.

David

This saga started because, when I left the boat for a couple of months, "kids" seem to enjoy unplugging the house side cable which, of my N46, that would shut down the 120vt fridge, spoiling all the food. This is a AT34 has 12vt fridge.

I had installed 2X140watt panels on my pilot house roof and a BlueSky controller.
Tied this to a 1500 watt inverter. I have 2 additional small inverters, a 200 and a 400watt, to support a couple of TVs and 2 additional 120vt outlets.

I also have a 12vt water maker that has not been used, to date. I had a brief discussion on 12vt vs 120vt. I figured with the main engine running, I can draw from the batteries to run the water maker as opposed to the necessity to run the generator to get 120vt.

I have a 12vt fridge.
I can support either the microwave, or a couple of 120vt outlets, if I am careful plus lights house lighting.
1 4D 200amp start battery
3 4D 200amp house batteries
Plus 1 12vt start battery for the 6kw gen.
The charger is 40amp.

If I am "nice", I can float for 2 or 3 days without running the gen. It is called "load management."

Of course, if I want to use the electric stove, hello generator. This will provide time to recharge the batteries and power to the electric HW heater. (The HW system is also tied into the main engine via a small heat exchanger too) The generator on the main engine is 150amp.

Could I have selected better stuff? Ah yup, you betchum Red Rider. Am I happy? I am happy and I hope the next owner will be happy too.

NOW, I am seeking recommendations on which ONE item should I replace to improve my system.

All goes back to sizing. Best advice is use the boat as intended then add solar accordingly. We are 300+ ahrs/day in the tropics with fridge, freezer, beverage fridge, laptops, fans, etc. We use 2 125adc inverter chargers while gen is running to charge batts.......etc. so a little panel would be spit.

So we are a little electrically intensive. But full time live aboards outside of the US on the hook, and nothing goes better with rum than ice. We run gen 2-3hrs every 2-3days in AM and let solar top the batts off. 3 yea s in and still averaging about an hour a day.

It is such a case by case application. Climate, latitude, equipment, etc. etc. to the OP, don’t factor it into purchase. If it’s there great, but f not, buy the right boat, use it, and add later based on your real world numbers.

Don`t overlook that solar panels can work on the batts all day, adding amps up to capacity, which would take an alternator or charger a long while to achieve.
I would like more solar but space is an issue,a modest 200watts of panel is still a very useful contribution to charging batts and feeding equipment.

BruceK said:

Don`t overlook that solar panels can work on the batts all day, adding amps up to capacity, which would take an alternator or charger a long while to achieve.
I would like more solar but space is an issue,a modest 200watts of panel is still a very useful contribution to charging batts and feeding equipment.

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BruceK, I agree. If that one solar panel can keep the batteries charged enough to keep the 12 vt fridge running, some lights on and the bilge pumps 'available', to me, it is a great investment.

Unless you have the equipment and understanding to monitor SOC etc. you are just guessing. 12.6vdc with 10adc going in vs. 10adc going out is a difference. And a 12vdc fridge and lights and vilge pump will run until you have completely destroyed a battery. So not a good measure. If not educated in these areas, investing in solar panels is a shot in the dark.

But there are many other threads that get more in depth, thread creep is getting to far.

Sealife said:

Unless you have the equipment and understanding to monitor SOC etc. you are just guessing. 12.6vdc with 10adc going in vs. 10adc going out is a difference. And a 12vdc fridge and lights and vilge pump will run until you have completely destroyed a battery. So not a good measure. If not educated in these areas, investing in solar panels is a shot in the dark.

But there are many other threads that get more in depth, thread creep is getting to far.

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I'd rather destroy the batteries than to have the boat sink.

We added 2 x 365W panels this spring for 730W total. We are in the PNW and are now 100% on the hook and living aboard.

So far I’m very satisfied with the results. We are running the genset to heat water and make coffee in the morning for an hour and that’s it. If we didn’t want to heat or make water we wouldn’t need to run the genset at all if the sun is shining. Batteries stay topped up during the day where before we’d be drawing them down - happy batteries make me happy.

Still early into this so time will tell but so far, life is way better with our solar installation.

My 2 cents. Third week on trip from home, near Bellingham to Broughtons in BC. 1 330 watt panel. Weather has been good. Zero time on gen set, and have not plugged in anywhere. Normal things running, including freezer. Batteries, never so far below 80%.

Ohhhhh, yes.

I love my solar panels, too.

Consider adding LFP batteries with the solar. Solar panels and LFP batteries are a match made in heaven because the LFPs can handle whatever charge power the panels can produce all the way to 100% SOC. Ideally, you should add LFP capacity in kWh that is 3x the wattage of the panels to get the most out of the system. You can connect the LFPs to your existing house batteries with DC to DC charger(s) and add an AC charger solely for the LFP batteries so you can recharge them from the genset or shore power if you wish to. You house batteries will still power the house loads on the boat, but the LFPs and solar will keep them at or near 100% SOC until the LFPs are dead, so the house batteries will last forever and your true house capacity will increase linearly by the capacity of your added LFP bank. By using DC to DC charging, you can put the LFP bank anywhere you wish too, it does not need to be near the house bank, but if you place it far away, consider using a higher voltage for the LFP bank to keep the bank to bank cables small.

I am in the middle of our solar install project. I have the MPPT controllers in and need to make the frame to mount the panels above the sundeck.

Victron is definitely winning some points with me on this install. The Venus OS on Rasperberry PI is pretty cool.

Got 2 of the panels mounted and so far so good. Waiting for some better weather to see some better numbers.

vancouvertechie said:

Got 2 of the panels mounted and so far so good. Waiting for some better weather to see some better numbers.

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So how did the install end up working for you? I am looking at putting some solar panels on our Tollycraft, but wonder about real world results in our part of the world. We have an all electric boat and the generator has been the weakest link in the last few years. (A number of trips have been cut short with issues) With 440 ah of battery I am not sure if it is feasible to be energy independent using solar panels at the 49th parallel.

If I could take the reliance on the generator out of the question it would make staying away from power for a week much more feasible.

Our Tolly came with a hardtop so guess what I eventually plan on mounting up there.. yep, a pair of panels. Going to need to measure to be sure which size to get but will buy the best set I can for the purpose.
Fortunately, panels are getting better every year as the technology evolves which is another plus. Along with the MPPT that is needed for them.
The downside though is that during the winter months there will be very little output from the panels due to the limited sunshine hours in the day and cloud cover. But our cruising in the winter is not likely to be that often. Don't need the drama of bad weather.....