Solar power in winter - useless?

[DangerousPirate]

I have a 175w flexible one and a 100w rigid one rigged to the boats batteries, and I barely make any input, certainly wouldn't be enough if I tried to live off the grid. How do other boats do that? Run the engine all the time? Or wind generator? But then I hear that wind generators are not as good as one would think, because we generally try to stay away from windy areas when at anchor or in marinas, obviously. At least that's the argument, and I am not sure if that's very true, but I am not ready to invest 500 quid or more just to find out.

On a regular day here in Northern Ireland I get maybe half an amp for a few hours a day, if it's exceptionally sunny (for the winter) I might get 1-2 amps. Of course I didn't expect the same output as I had in the summer, but I thought a little more would be achievable. But this is next to nothing really. With 275w, almost 300w, and I can't even run my lights in the evening

I use more power than I could charge up, certainly couldn't run a diesel heater on that. At the moment I don't run a fridge or heater or anything, only lights, and as I say, the half an amp for a few hours a day are not going to counter that by much. So I am constantly at shore power, and I don't think I will be able to use a diesel heater without having to run the engine every so often.

Any advice?

 

[Chiara’s slave]

You get about 10% of your summer output in winter. In N.I. I daresay thats not a lot. Even in one of GB’s sunniest spots we get just that 10%. You need more panels, is the answer. We don’t need 400w in summer, but we do need 40w in winter.

 

[William_H]

Yes there is no way around the lack of sunshine in winter in UK. As said more panels will get more current in winter but you may not have room for m ore panels. In which case I think running the engine for extra charge is your best bet. There seems to be down sides to wind gen like noise cost and susceptibility to damage.
If you are moored for a period in winter you might be able to find room for a domestic PV panel typically about 1 m by 2m and 300w output at 40 v. Needs MPPT controller for 12v system. Then orient it towards south. It might give you more solar power less engine run time needed. (you do have a smart regulator I hope) Or at least a charge current amp meter to monitor engine charge current. ol'will

 

[DangerousPirate]

I was looking into a cockpit enclosure, so that would give me plenty of room for solar panels. I could take them down when I am sailing, and put them back up for longer stops. But not sure how quickly I will get that up there.

 

[Tranona]

On a boat the size and type of yours it is unrealistic to expect to live off grid, even in the summer because you simply don't have enough space for enough solar to meet your daily consumption. First thing is to do an audit of your usage then look at the size of battery bank required for the time you want to be away from shoreside power. So if you are using 80 amps a day the a 200Ah bank would comfortably give you a day "buffer" without discharging below 50%. Then look at how much you can put back in - the more you can get from solar the less you need from other sources. Running the engine is a poor and inefficient way of charging your batteries - typically it takes an hour to put in 10-15 amps, particularly if the battery is 50%+ charged already. Running the engine for long periods with light loads is bad for it. Cockpit enclosures are very expensive, but obviously have huge benefits for living on a small boat. They do give the opportunity to increase the area of solar, but it is a lot of work to mount and remove so really only practical if you are spending long periods moored up. As you have found output is poor in the winter which is probably when you will be moored up - but that is also when you have access to shorepower.

Realistically if you are spending time on board you need shorepower if you want to use electricity for light and running the heating. When you are away cruising, although the principles are the same in that you have to match power generation to consumption the actual figures are different and you have more choices about generation, particularly in the summer.

How do others manage? just the same as you. It is possible to live off grid on a boat if you don't rely on electricity. If you want to use electricity you have to generate it. The obvious first step is to keep demands low , for example using LEDs for lighting, insulating your fridge if you have it, installing a heater that is not reliant on electricity and so on. However as you have discovered you very quickly hit the limit of what you can generate yourself so a generator or shorepower is the only answer.

 

[coopec]

Yes there is no way around the lack of sunshine in winter in UK. As said more panels will get more current in winter but you may not have room for m ore panels. In which case I think running the engine for extra charge is your best bet. There seems to be down sides to wind gen like noise cost and susceptibility to damage.
If you are moored for a period in winter you might be able to find room for a domestic PV panel typically about 1 m by 2m and 300w output at 40 v. Needs MPPT controller for 12v system. Then orient it towards south. It might give you more solar power less engine run time needed. (you do have a smart regulator I hope) Or at least a charge current amp meter to monitor engine charge current. ol'will

Hi Wii
I always appreciate your comments.

Now I'm confused though when you say "Then orient it towards south." Is that a slip of the pen, did you mean North?

Whenever I have visited Fremantle and Hillarys marinas and come across overseas registered yachts on extended cruises (with their washing hanging over the safety lines) they all seem to have wind generator (one of them had two) Something doesn't add up as many people say, like you, they are costly and noisy. Now I have just t read your post of Jan 2022 and it explains a lot but I still think I'll get one.

QUOTE "The turbine in the link seems to have a powered field coil taking 15ma whether charging or not. May be a concern. It is claimed that it has an MPPT regulator giving 13.2 volts if I read correctly. Not enough for fast charging of a largish battery. Now Chinese have often claimed MPPT for a solar regulator when it is not. Just PWM.
MPPT is vital for wind gen as without it a low wind speed giving low output volts will not get any charge in to a 12v LA battery. It must be more like 14v which requires quite a good wind.
My friend bought some years back a Chinese 12v turbine for a remote property. It had permanent magnet field and 3 phase out put from stator coils. The very impressive looking "regulator" simply contained 6 diodes to rectify the 3 phase AC. It did give some charge at decent wind strength but ultimately dismantles itself in a strong wind. So he went to rely on solar charge. Can't tell if this one is any better. If you do buy one give it a good check out at home before you go to the cost of permanent mounting on your boat. Connect it to a 12v battery with an amp meter and check at various wind speeds. ol'will UNQUOTE

 

[AngusMcDoon]

So if you are using 80 amps a day then a 200Ah... typically it takes an hour to put in 10-15 amps..

Units stew!

 

[coopec]

""Then orient it towards south." Is that a slip of the pen, did you mean North? "

OMG! I better not start off on a circumnavigation!? Point it South towards the equator.
My apologies!

 

[Sandy]

deleted.

 

[Graham376]

I have a 175w flexible one and a 100w rigid one rigged to the boats batteries.....................
On a regular day here in Northern Ireland I get maybe half an amp for a few hours a day, if it's exceptionally sunny (for the winter) I might get 1-2 amps. Of course I didn't expect the same output as I had in the summer, but I thought a little more would be achievable. But this is next to nothing really. With 275w, almost 300w, and I can't even run my lights in the evening
Any advice?

Have you checked the output from the panels? Only half an amp from 275w seems far too low. Before we headed south, we used to get higher winter charge than that with less panels in N Wales.

 

[Blueboatman]

My only suggestion is to read /copy advice from those who have done it .
Build a cockpit enclosure with 2,3,4 PV above ( buy a sewing machine , it’s a winter project )
And fit one or more wind generators
You’ll be ok
( think of each acquisition as one months marina /shore power rent if you will)

 

[Trident]

I have needed shore power only for cooking this winter (all electric galley boat) and on days like today (sunny in the solent ) I'm cooking and making hot water off the solar again. I was off shore power for everything including hot showers etc all off solar from March til November...BUT I have almost 2kw of solar panels on a 50 foot cat. I could do better if I could be bothered to hook up more solar at a steep angle - I designed things so that I could hang lightweight 200w panels (x2) from the side of the cockpit canopy to point in to the sun at 90 degrees and move them around the front of the canopy as the sun moves. This angle of incidence will give 3X the power they give flat but I use so little shore power anyway I've just not been bothered.

To live comfortably off grid needs a big boat and a lot of panels. I think if I added wind I could last all winter off shore power but the noise is not worth it and we're heading for the sun this year anyway

 

[Graham_Wright]

I am in the process of installing a generator for the same reason. I could motor across the bay (Cardiff) and spend £18 on 24 hours of shore power I suppose.

 

[srm]

You output seems low, both orientation and angle of inclination will make a big difference in winter. I don't know your panels are installed but horizontal panels will not catch much energy with the low angle of the winter sun.
More wind in winter so a wind turbine can make a useful contribution depending on your mooring location. My AirX was uncomfortably noisy at times when I got it back in 2005 but changing the blades for a Silentwind set made a tremendous improvement. Modern turbines have improved on the noise front, (Silentwind have progressed to selling a full system now having started with blades for the AirX) but try listening to a few in a fresh breeze before making the plunge.

 

[AntarcticPilot]

I agree with those who say the output seems too low. I have 2.2 kW solar panels on the roof of my house, and in winter I expect (based on my feed-in tariff payments) to get around a third of the summer output. While the hours of sun are less, there are usually many clear periods in the winter, and it is light, not heat, that is being converted to electricity. A further factor is that the efficiency of solar panels is better at low temperatures! Admittedly my house roof is pretty much optimally oriented, and also is not shadowed, but if I were you, I'd be investigating your system. Are your panels individually protected against reverse voltages by diodes? That makes a BIG difference.

Concerning wind generators, I had a Rutland 900 series generator with an HDRi controller for many years. It never made very much; the manufacturers state that it won't start generating until you've got 15 knots wind, and that's quite a lot at deck level in a marina.

 

[Chiara’s slave]

From my solar experience, having a separate charge controller per panel can make a huge difference. Unless they all point the same way and are equally shaded, the output will be different, and the controller will ‘default’ to the crappiest output. Even multiple pwm controllers are a better bet than a single mppt. Obviously best to use multiple mppt controllers. We have 4 panels and 4 controllers, but all our panels are deck mounted, pretty much flat. That’s poor in winter, but there’s nowhere else on our boat.

 

[NormanS]

Just to give a seasonal comparison between the power generated by PV panels on the roof of our house, in the summer months we average about 300 units / month.
In the winter months, it's about 50. We are in Central Scotland, so have short daylight in the winter, but long in the summer.
Horizontal panels mounted on a boat will always be poor in winter, at our latitude. The best way to boost their output, would be to angle them up to face the sun.
Our boat is laid up in the winter, and a part of the panels is under a cover, but that still leaves plenty for a battery maintenance charge.

 

[IanCC]

I have a 175w flexible one and a 100w rigid one rigged to the boats batteries, and I barely make any input, certainly wouldn't be enough if I tried to live off the grid. How do other boats do that? Run the engine all the time? Or wind generator? But then I hear that wind generators are not as good as one would think, because we generally try to stay away from windy areas when at anchor or in marinas, obviously. At least that's the argument, and I am not sure if that's very true, but I am not ready to invest 500 quid or more just to find out.

On a regular day here in Northern Ireland I get maybe half an amp for a few hours a day, if it's exceptionally sunny (for the winter) I might get 1-2 amps. Of course I didn't expect the same output as I had in the summer, but I thought a little more would be achievable. But this is next to nothing really. With 275w, almost 300w, and I can't even run my lights in the evening

I use more power than I could charge up, certainly couldn't run a diesel heater on that. At the moment I don't run a fridge or heater or anything, only lights, and as I say, the half an amp for a few hours a day are not going to counter that by much. So I am constantly at shore power, and I don't think I will be able to use a diesel heater without having to run the engine every so often.

Any advice?

This time of year, half an amp is fair to good, in my experience in Yorkshire. It's a battery maintenance thing.

 

[William_H]

Hi Wii
I always appreciate your comments.

Now I'm confused though when you say "Then orient it towards south." Is that a slip of the pen, did you mean North?

Whenever I have visited Fremantle and Hillarys marinas and come across overseas registered yachts on extended cruises (with their washing hanging over the safety lines) they all seem to have wind generator (one of them had two) Something doesn't add up as many people say, like you, they are costly and noisy. Now I have just t read your post of Jan 2022 and it explains a lot but I still think I'll get one.

QUOTE "The turbine in the link seems to have a powered field coil taking 15ma whether charging or not. May be a concern. It is claimed that it has an MPPT regulator giving 13.2 volts if I read correctly. Not enough for fast charging of a largish battery. Now Chinese have often claimed MPPT for a solar regulator when it is not. Just PWM.
MPPT is vital for wind gen as without it a low wind speed giving low output volts will not get any charge in to a 12v LA battery. It must be more like 14v which requires quite a good wind.
My friend bought some years back a Chinese 12v turbine for a remote property. It had permanent magnet field and 3 phase out put from stator coils. The very impressive looking "regulator" simply contained 6 diodes to rectify the 3 phase AC. It did give some charge at decent wind strength but ultimately dismantles itself in a strong wind. So he went to rely on solar charge. Can't tell if this one is any better. If you do buy one give it a good check out at home before you go to the cost of permanent mounting on your boat. Connect it to a 12v battery with an amp meter and check at various wind speeds. ol'will UNQUOTE

Hi Clive My experience of wind turbines is pretty limited largely coming from this forum with the exception of that case described. Perhaps or the OP wind turbine might be useful. However for your lovely new boat no I think a bit of solar would be useful. Then get the boat out and in use. I think you may find solar in our latitude and some engine running will keep you good. Re engine running for battery charge apart from a smart charger the simple way to imoprove productivity of engine charging is with bigger batteries. They will take more current fro longer time so giving more overall energy available even if batteries are not fully charged. Perhaps the wind gen is a status symbol of "world cruiser boat" more than actual charge needed. ol'will

 

[DangerousPirate]

Maybe I should just rig a solar panel inside the cabin and charge the batteries with the cabin lights. That should work. Patent pending. Is It Possible To Charge Solar Panels Without Sunlight?.

Yeah, not sure really how much solar I need for days like these in latitudes. Probably will wait for the cockpit enclosure, and then rig pockets for the solar panels to mount them. I have a big cockpit, so I can fit quite a lot of solar panels on there. I am fairly sure that 400-500w should be possible. Maybe I experiment with flexible solar panels hung from the railings first. Not sure. But I think the winter will be over before I get to do anything really. It's already January, might be a problem for next year considering how slow projects like this go sometimes.

Still curious how many watts I would need in winter. ?