Generators needed on boat with solar and lithium.?

[CaptainRivet]

Originally Posted by toddster8

Winter.

Even in summer, with refrigeration, freezer, and starlink, there is often a deficit at the end of the day that requires an hour or so of running the generator. Yeah, get more solar panels. Somehow. But then, winter.

You need to fit more solar or if you have older generations exchange them to bifacials.
You calculate to panel for autum and spring, in summer you should nearly always have too much.
Only then your self sufficent on solar and in winter get by by running your engine with big alternator every 3rd or 4th day for an hour or two. Yes less efficent but in the end less maintenance and cost plus reducing complexity.
I stay far below the 400h per year maintenance so always the yearly maintenance scedule kicks in. so running it a bit more often won't change any maintenance or make it more expensive.
Without aircon 2,5kw solar gives you that. With 12/24V aircon 3,4kw solar is needed....230V aircon well a small one for owner cabins works but for majority of boat either 230V and gen or 12V/24V aircon wirhput gen...

[toddster8]

Originally Posted by CaptainRivet

You need to fit more solar or if you have older generations exchange them to bifacials.
You calculate to panel for autum and spring, in summer you should nearly always have too much.
Only then your self sufficent on solar and in winter get by by running your engine with big alternator every 3rd or 4th day for an hour or two. Yes less efficent but in the end less maintenance and cost plus reducing complexity.
I stay far below the 400h per year maintenance so always the yearly maintenance scedule kicks in. so running it a bit more often won't change any maintenance or make it more expensive.
Without aircon 2,5kw solar gives you that. With 12/24V aircon 3,4kw solar is needed....230V aircon well a small one for owner cabins works but for majority of boat either 230V and gen or 12V/24V aircon wirhput gen...

LOL. I was thinking of going from 400 watts to 800. Which would overhang the stern quite a lot and be a big problem on seawalls and locks. Not to mention windage. Still wouldn't do anything in PNW winter. Most days are really dark and short.

Option 2: Head south... Ah, but then: Air Conditioning.

[smj]

From my experience we take in less solar in the winter but also have a smaller draw because the refrigerator doesn’t run as much, works out being a wash.

[noelex 77]

Originally Posted by CaptainRivet

Without aircon 2,5kw solar gives you that.

It is very hard to generalise about the amount of solar needed. Efficiency of production and consumption vary enormously, as does solar insolation.

We run electric cooking, a fridge, freezer electric heating for shower water, a watermaker plus all the other usual toys on less than half the amount you quote, but this will not apply to every boat

Unfortunately, you need to do your own sums.

[sailingharry]

Originally Posted by CaptainRivet

Without aircon 2,5kw solar gives you that. With 12/24V aircon 3,4kw solar is needed.

And with that, you have exactly made the case for a generator. As discussed in the other thread on solar panel size, I am struggling to put 750 watts on my arch, to supplement 200 watts of poor performing Solbian on my bimini. (I have struggled unsuccessfully to find any panels to replace those disasters). So I am running about 1/3 of the solar that you say is the easy answer to a generator. And if I had air conditioning of any sort, which I don't, I would have about 1/4 of the solar necessary.

I do believe that my full-time power load on a 43 ft monohull is about 2.5-3 kWh per day, so I can probably survive with no additional generation beyond solar. Except for any days where I don't get full solar, or days in northern latitudes, or days in the winter time.

Like you, I have a lot of engine mounted generation, easily 2 kW, and since we rarely see a week without at least 15 hours of motoring, our generation makes up the shortfall. But many cruisers stay stationary for extended periods, and a generator is far superior to running a main propulsion engine for electricity.

[merrydolphin]

You absolutely do not NEED and generator with good bats and solar/wind/water what ever charging, BUT. They are nice if you have space and budget.
I cruised full time anchoring 95% of the time for 9 yrs in our Kelly Peterson 44 cutter. We didn’t have a generator and didn’t really miss it. Our next boat came with a genny and yeah, it was nice. Mainly used it for the 110V 20+ gph water maker. Just ran it once every 2 wks. We had a 12VDC water maker on the Peterson 44. There are a handful of times when we really would love to have air cond. but really very few. We didn’t have it on either boat. East coast of USA in the summer could be brutal but we stayed away for the most part. Caribbean and Pacific no real need for AC until the Sea of Cortez. There are a couple of months in the summer that are brutal. But with my budget, not worth 20 grand for a couple of months out of 9 yrs.

[CurtD]

I have a duel fuel 3500w generator that's compact enough to stow and use it when my solar can't keep up. I fuel it with what I have more of at the time, but it is more efficient on gasoline.

[Chotu]

Originally Posted by smj

From my experience we take in less solar in the winter but also have a smaller draw because the refrigerator doesn’t run as much, works out being a wash.

This is my experience also

[Chotu]

Originally Posted by sailingharry

And with that, you have exactly made the case for a generator. As discussed in the other thread on solar panel size, I am struggling to put 750 watts on my arch, to supplement 200 watts of poor performing Solbian on my bimini. (I have struggled unsuccessfully to find any panels to replace those disasters). So I am running about 1/3 of the solar that you say is the easy answer to a generator. And if I had air conditioning of any sort, which I don't, I would have about 1/4 of the solar necessary.

I do believe that my full-time power load on a 43 ft monohull is about 2.5-3 kWh per day, so I can probably survive with no additional generation beyond solar. Except for any days where I don't get full solar, or days in northern latitudes, or days in the winter time.

Like you, I have a lot of engine mounted generation, easily 2 kW, and since we rarely see a week without at least 15 hours of motoring, our generation makes up the shortfall. But many cruisers stay stationary for extended periods, and a generator is far superior to running a main propulsion engine for electricity.

Exactly. And further proving the need, once you have enough space on the coach roof to house massive solar, your need for air conditioning power goes WAY up.

36,000 BTUs of air conditioning is just enough for my boat. Now how much solar do I need to power that all day long and a little into the night?

[Alchemist 4764]

Originally Posted by Simi 60

Yep
But I doubt it'll run our smallest charger 50amp @ 24v
It might run our watermaker
Therefore, in our eyes it's a small job generator.

50 amps @ 24 volts is 1200 watts. All but the smallest Honda generator will cover that without breaking a sweat.

[rslifkin]

Originally Posted by Chotu

Exactly. And further proving the need, once you have enough space on the coach roof to house massive solar, your need for air conditioning power goes WAY up.

36,000 BTUs of air conditioning is just enough for my boat. Now how much solar do I need to power that all day long and a little into the night?

Depends on the weather and your heat tolerance. For me, I tolerate heat better during the day than when sleeping, especially if it's a humid night. But at night, you don't need to cool the whole boat, only the area where you're sleeping, which significantly reduces the power requirement.

Cooling your entire boat with solar powered A/C is likely a challenge, but being able to keep your sleeping cabin cool without running a generator overnight is much easier to achieve.

[Simi 60]

Originally Posted by smj

From my experience we take in less solar in the winter but also have a smaller draw because the refrigerator doesn’t run as much, works out being a wash.

But we also have hotter showers,
Use outside gas Bbq less in favour of indoor induction, air fryer oven or electric pressure cooker.

That definately has us running Genset by day 3

[Bill Streever]

Pulled out our diesel generator last summer. Didn't miss it a bit. Now have folding bikes and other gear stored in the gen set locker. Engine alternator acts as a backup for times when the sun doesn't keep up (which has not happened yet).

[fxykty]

It depends on where and when you are cruising and the amount of solar insolation present. What works in predominantly sunny regions and/or seasons will not be enough in cloudy/rainy regions and/or seasons. Just getting more solar or more efficient solar within the limits imposed by most boats is not enough on its own, unless you are permanently based somewhere sunny and clear.

We increased our solar panel acreage, removed a diesel generator, and replaced stock alternators with high output alternators on both our engines. The solar is sufficient around Australia most of the time for our relatively hungry energy budget, but won’t be enough when we winter cruise in Japan and the Pacific North West, or during the wet season in SE Asia. Maybe we’ll need to get a portable generator to avoid excess main engine charging?

[noelex 77]

Originally Posted by fxykty

It depends on where and when you are cruising and the amount of solar insolation present. What works in predominantly sunny regions and/or seasons will not be enough in cloudy/rainy regions and/or seasons. Just getting more solar or more efficient solar within the limits imposed by most boats is not enough on its own, unless you are permanently based somewhere sunny and clear.

We increased our solar panel acreage, removed a diesel generator, and replaced stock alternators with high output alternators on both our engines. The solar is sufficient around Australia most of the time for our relatively hungry energy budget, but won’t be enough when we winter cruise in Japan and the Pacific North West, or during the wet season in SE Asia. Maybe we’ll need to get a portable generator to avoid excess main engine charging?

It is important to realise, as Fxykty correctly points out, that solar production varies significantly depending on location and the season. Formulae for the expected solar production is often quoted on this forum, without a proper explanation that these expectations will only be met in some cruising areas. In some locations and times of the year the formulae are hopelessly incorrect.

However, modern solar panels can still collect enough electrical energy so you can run boat happily even in areas of poor solar insolation without a generator, so don’t think this is not feasible. You need to prioritise electrical efficiency and have alternative non electrical systems in place for high draw appliances. This is better than putting up with drawbacks of generator in my view, but YMMV

Many modern boats are set up to exclusively use devices such as electric cooking and water heating. I don’t think the owners always realise that the boat set up is going to confine their cruising area to areas of good or even excellent solar insolation. Electric cooking and water heating is easy and convenient. We use this in areas of reasonable solar insolation. I would strongly recommend installing these systems, but you need alternatives if you want to cruise the many wonderful areas with poor solar insolation, without the hassle of a generator.