Solar vs wind vs hydro

[Drunkonwatch]

https://www.epropulsion.com/

Interesting

[Networker]

Originally Posted by Adelie

I was thinking something like this:

https://www.tesup.us/product-page/at...ine-for-houses

After researching, this one has a better output curve and the idea of putting 2 on the mast seems like a great idea. https://phileole.com/en/product/phileole-sailing/

I’m going to go this route I think when getting wind gen this year. Just asked for a price quote.

[Pete7]

Originally Posted by JebLostInSpace

Going back to your original charts, I'm surprised that you are prioritizing the hydro over the wind. I agree that solar expansion should be top priority.

Disclaimer: I've never had or used either hydro or wind, so all of this is potentially worth less than the proverbial 2 cents.

I thought the requirement was for summer cruising? Quote from the first post:

Originally Posted by bergius

We currently cruise the Baltic Sea for the 5-6 month sunny half of the year, and need shore power for the winter months. The boat is a 31ft Amigo 40 double-ender.

Problem is were to put a windmill on a 31ft sloop?

The other point is the weather in the Baltic. Admittedly its been some years since I sailed there. However, barring an occasional gale, summer sailing was heavily influenced by sea to land breezes during the day. At breakfast time, it would be calm, then slowly build during the day to F4-5 at lunchtime and die down again at tea time with a still night. The effect was caused by the shear size of central Europe to the south heating up each summer day.


The 200w output in 16 knots of the vertical wind gen above doesn't seem worth the while. Larger horizontal ones go were?

Pete

[hpeer]

Has anyone here been following Nigle Calder? I have not but he was doing a fair bit of work on solar for boats, EU funded program, and his geographic region was Baltic/ Norway. IIRC his research was that solar beats wind even in Norway.

I have a diesel heater/stove in my hunting cabin, love it there, but it is not for the boat. There I use Espar. But this tooic js almost as bad as “which anchor” threads.

I have an Aero6gen wind generator. Boat we t through a hurricane while in storage and lost 5 blades. I replaced, no big deal. Recently I had the main sail halyard come loose (my bad) in a windy anchorage. I took off one blade. The vibration in my arch was AWSOME. Thought I was gonna loose the whole arch. I was thrilled when the halyard came back and took iff 4 more blades and stopped the vibration. I see a lot of arches that are much more lightly built than mine.

The point being some attention need to be given to arch design for big winds and other stressful events. If course this then effects the boats balance and performance and compromises need to be made.

[noelex 77]

Originally Posted by Pizzazz

Your aversion to using the engine to charge hinges on the misconception that you can only draw 50% of the alternator rated current which I have never heard before and there is no physical reason for it.

Most standard alternators fitted to marine engines will not deliver their rated power for long without overheating. Some will automatically reduce their output, others are damaged. This is not a problem with a smaller lead acid bank, as the batteries will not accept a high current over a long time period, but with a large battery bank (especially lithium) many wire their alternator in such a way that the output is permanently limited or reduced when the alternator temperature rises.

The 50% figure is arbitrary, but is a common starting point. Monitoring alternator temperature is the best way to determine if it is safe to increase this derating.

A better solution is to install an aftermarket alternator that has a reasonable continuous rating.

Originally Posted by Pizzazz

You can't have hot water on solar or wind power.

This is possible with a larger solar array when cruising areas of reasonable solar insolation, providing you have efficient systems. Our solar panels provide all our hot water both for showers and drinks in most locations. Higher latitudes in winter are cold enough to use our diesel heater so this takes over providing hot water if we are cruising these areas.

[bergius]

Originally Posted by Pizzazz

On my Hunter 31 in California, I replaced the 35A with an 80A alternator first (it was supplying around 60-65A), then with a 120A alternator (giving me around 80-85A). This is without any external regulators. These alternators cost $100 on Amazon and mine lasted for years. Not that difficult to replace if it fails.

Do you have a lead-acid or LiFePO4 battery bank? Everywhere I’ve read says you should limit the current you draw from a dumb alternator when charging a LiFePO4 bank, or otherwise you’ll fry stuff.

Na Mara has a totally different situation with his smart alternator controller that both monitors the alternator temperatures and talks to the BMS. We could maybe install one as well, but it is a pricey setup and, as said, we don’t like running the engine.

Right now we have the situation where we’re not depleting the batteries when motoring, and that was the goal of the alternator upgrade. We might be able squeeze another 9-12A safely out of it, but that’s pretty much as far as it stretches.

Originally Posted by Pizzazz

Use the 5kW Chinese diesel heater to warm up the cabin (I had one and I was super pleased with it... it draws outside air, makes the boat cosy and dry)

That’s what we have right now. Works pretty well even when temperatures are below freezing. But a drip-pot heater would save on electricity and bring some nice ambience into the saloon.

[Pete7]

Originally Posted by bergius

Right now we have the situation where we’re not depleting the batteries when motoring, and that was the goal of the alternator upgrade. We might be able squeeze another 9-12A safely out of it, but that’s pretty much as far as it stretches.

Like you we changed the 32 year old Valeo 50A alternator for a 100A OEM alternator. The Valeo output 42A but only briefly before dropping like a stone. The replacement does 50A at cruising revs for several hours if necessary. However, since it runs on a 9.5mm belt as apposed to later Volvo engines on 12.5mm (I think) I am reluctant to push how much power we generate with the alternator. More could be possible, but new pulleys and serpentine belts aren't a cheap option.

We limit alternator charging with a Victron Smart Orion DC>DC charger to 30A. However, and it seems difficult for people to understand, this isn't our primary charging system, solar is. During a 3 week cruise in 2021, we used the alternator to charge the house bank twice!

Does solar work at higher latitudes, yes. Can it heat water during the summer? well we are working on it

Pete

[bergius]

Originally Posted by Pete7

Problem is were to put a windmill on a 31ft sloop?

Especially with the canoe stern. We were talking with Superwind last winter and they actually declined to sell us a unit as they were of the opinion that we don’t have a safe place to mount one.

We were given a small wind generator to try back in 2021, before we had the solar arch. Unfortunately this old unit was never able to get to voltages you’d need to charge even a depleted LiFePO4 bank, so we gave it onwards.



The manufacturer has a modernised version of the same wind gen, and I saw a few of the GGR boats carry these. It might fit without shading the arch. I wonder if that’d make sense. Output seems to be quite minimal.

Though the mast-mounted vertical wind generators shared in this thread sounded very interesting as well!

[Na Mara]

Originally Posted by bergius

Though the mast-mounted vertical wind generators shared in this thread sounded very interesting as well!

I concur very strongly with regards to the Grain Blanc (Phileole) VAWT. Compared to standard HAWT turbines its stats aren't that impressive at first glance. Startup speed is 8m/s (silent wind is 3m/s), output at 14m/s is 100W (Silent wind is 420W), etc. But it should be a good deal cheaper to purchase due to not requiring mounting structures. It should also produce much more inline with its stats than the HAWTS do as VAWT turbines are much less sensitive to pitch and yawl motions throwing them out of alignment with the wind, or from general turbulence from nearby obstructions. They are also mounted higher up and so don't suffer as much from wind shear or wind shadowing from shore side obstructions. Safer too due to being farther from the crew, slower in rotation, and more solidly constructed. Apparently silent. Comes off with the mast for winter storage. The slot effect from the foresail might also enhance the output.

I could probably put two of them up my mast no bother. As average wind speeds in the Baltic tend to be around 10kn (5m/s) they wont generate much most of the time, but on windy days they would put out 100-200W together and being on the mast they would do that without blanketing the solar. On a windy day you might net 3-4kWh from them assuming big enough batteries.

I have to say I am tempted, but I'd need to see the unit price first.

As to the whole hot water from solar thing; its perfectly doable during the summer, even in the Baltic. It takes just over 1kWh of energy to raise the temperature of 40l of room temp (20C) water to a shower worthy temperature (45C). It will take the average 750W immersion heater 80 minutes to do this assuming no heat losses and 100% efficiency. Allow 90% efficiency on the element and another 10% off in losses from the tank. Then it takes 1.25kWh of electrical energy over 100 minutes to get the tank to shower temp. Assume you do this once a day for showers and rely on your kettle (LPG, though I do this on electric) for washing up. The easiest set up is to run the immersion heater off the inverter. Inverter efficiency is typically about 90%. Assume you have solar charging lithium batteries so there are basically no charge or discharging inefficiencies. Then you will need about 1.4 kWh of solar input to heat enough water for showers. Assume the standard 4 times rated wattage as daily average kWh generated. Then you are going to need about 350W of additional solar over what you need for all other needs in order to meet water heating needs as well, assuming you shower daily. Half that if you shower every other day and so on. Its perfectly doable. Showering every other day, a pair of guardrail mounted Flinrail panels would do it.

This is on my to do list for next season. First I'll wire up the immersion heater through the inverter on a timer switch and see whether the math holds in practice. Then, if I'm short on energy, I'll add a couple of guardrail panels.

[noelex 77]

Originally Posted by Na Mara

I. Then it takes 1.25kWh of electrical energy over 100 minutes to get the tank to shower temp.

The traditional boat calorifier is not a very efficient way to produce hot water for a shower.

On our boat a generous hot shower for two needs about 0.5 -0.6 Kwhrs. This only heats enough water for the shower, but it is well under half what is typically needed. If energy is in short supply we can reduce or eliminate the electrical consumption by warming some, or all of the water using solar thermal, propane or diesel.

[Pete7]

Assuming lithium battery bank, would it be better to just run an electric shower off an inverter? Hadn't really thought about this, but why heat and try to store lots of hot water which certainly our calorifier doesn't and goes lute warm over night.

Pete

[bergius]

Originally Posted by Pete7

Assuming lithium battery bank, would it be better to just run an electric shower off an inverter? Hadn't really thought about this, but why heat and try to store lots of hot water which certainly our calorifier doesn't and goes lute warm over night.

The ones I’ve seen on Amazon were all >5000W, so you’d need a pretty hefty inverter to run that.

We don’t have hot water on board at all. For cockpit showers we heat some water on the stove and use one of those pressurised garden sprayers. In winter you shower pretty quickly

[Pete7]

Originally Posted by bergius

The ones I’ve seen on Amazon were all >5000W, so you’d need a pretty hefty inverter to run that.

Just had a look, seems that ordinary UK 230v models are 8.5kW and upwards, so forget that idea, shame.

Pete

[Na Mara]

Originally Posted by noelex 77

The traditional boat calorifier is not a very efficient way to produce hot water for a shower.

On our boat a generous hot shower for two needs about 0.5 -0.6 Kwhrs. This only heats enough water for the shower, but it is well under half what is typically needed. If energy is in short supply we can reduce or eliminate the electrical consumption by warming some, or all of the water using solar thermal, propane or diesel.

The amount of energy needed to heat the water is a hard physical fact. If you need only 0.5-0.6 kWh to heat your water to shower temp then either you are heating less water, or you have less of a difference between room and shower temp, or both. That amount of energy would only get 40l to a bit north of 30C from 20C which is a bit hardy for showering in comfort. It would, however, get 20l to a toasty 45C from 20C and that is enough for two decent but not luxurious showers.

Solar thermal is a good idea. I do it for deck showers if rinsing off from a dip I the oggen but then I use one of those camping gravity solar showers. If you are doing cockpit showers in the Baltic winter then you are a tougher nut than me bergius!

[noelex 77]

Originally Posted by Na Mara

It would, however, get 20l to a toasty 45C from 20C and that is enough for two decent but not luxurious showers.

The secret is not bending the laws of physics, but only heating the water you will use and having almost no inefficiencies or thermal loss. 45°C is too hot for showering when there is little loss of temperature in the pipes. In winter we heat the water to 40C and summer around 38C.

100% efficiency would give us between 22L (0.5 Kwhrs @40C)and 29L (0.6 Kwhrs @38C). No system is 100% efficient, but our shower system is close. This is enough for generous showers for two especially as there is no water wastage because there is no waiting for the water to become hot enough and no need to dial in the correct temperature.

Of course if you want more or less water this is easily done and the efficiency remains the same. For example, if all you want is a quick 5L boat shower for one , this can be had for not much more than 10 Ahrs @12v so it is achievable on even a small yacht with a very modest electrical system.

Originally Posted by Na Mara

Solar thermal is a good idea. I do it for deck showers if rinsing off from a dip I the oggen but then I use one of those camping gravity solar showers. If you are doing cockpit showers in the Baltic winter then you are a tougher nut than me bergius!

The camping gravity showers are very basic. The water is generally too hot or too cold and the water pressure and flow are very low. However, water can be heated using the same solar thermal technique then added to pressured indoor shower with further hot or cold water added so it is the ideal temperature. The quality and comfort of the shower does not change, just the means of heating the water.