DC generator vs full solar/wind solution

[RaymondR]

Originally Posted by socaldmax

The Kubota DC gen+watermaker+fridge compressor is a pretty interesting idea. I suppose every time the fridge cycles the compressor, it makes a bit more 12v power and some more water. It's still a diesel gen, so you'll have to carry fuel for it, but it is a pretty slick bit of packaging and a Swiss army knife type of solution to the perennial DC power, water and refrigeration problem.

I am in the process of building a DC gen and compressor unit mainly for redundancy purposes and to allow me to run a microwave for extended periods without pulling the batteries down.

About once every two years or so I find I have flat cranking batteries or house batteries, this happens for various reasons. At the moment I use a small engine driven 2.2kW genset and an inverter welder for emergency recharge or starting, unfortunately using it to start engines usually blow the capacitor in the generator. Recharging house batteries does not cause a problem however I must carefully watch the voltage to avoid damaging the batteries.

I am considering putting a water heating jacket on the exhaust of the new DC genset to provide heating for a small hot water storage tank, not a big problem to implement and if I use the microwave fairly often should provide a good supply of hot water.

I would not bother with the wind generator unless you are going to spend a lot of time in high latitudes during winter. I have one but because I tend to stay in warm climates it does not contribute much charge to the batteries, most decent anchorages are not windy anyway and they don't work very well when you sail mostly downwind.

If you are going to spend a lot of time away from marinas and have enough room you might consider a washing machine and these tend to be a bit power hungry, hence the auxiliary charger might be handy.

I suspect that in five years time the LiPo battery technology may have fully matured and one will not require the extensive lead acid battery banks we now have. I have 4 banks of 12V 220 amp hour Trojans and 520 Watts of panels to charge them. I have found that if you want to get a reasonable life out of the lead acids you should restrict discharge to about 25-30% of total amp hour capacity. An auxiliary charger would better exploit the high charging currents that these batteries can tolerate.

I only run a small portable fridge, TV and lights but at the moment it is a constant cycling fridge. I am rebuilding the fridge as a 12V eutectic with 24 hr 7 day timer control so that the fridge can exploit the extra power available during the day and not run during the night when battery drawdown is at a maximum.

With the changes in battery technology and more extensive comforts and conveniences we are tending to put aboard our boats (be mindful that you are aging and if you want to extend your cruising into later life where personal energy budgets intrude you might want to aim for a bit more comfort and convenience) power systems appear to be in a state of flux at the moment.

I would tend to spend a few years of the next five becoming familiar with what your requirements may be before doing a final design for your boat.

I have been a permanent live aboard since 2000 and continuously cruising the Australian coast since 2002.

[cruisersfarm]

As has been said, it's not either or.

Depending how you use your energy, both may be best.

I currently only have a 5kw generator and 440ah standard batteries. Batteries I killed by forgetting to turn off a small load while away from the boat 6 months ago.

The setup isn't working well because it's annoying to run the generator to keep up with small loads like tablets and the anchor light.

If you need a generator for air conditioning or to run a watermaker with some oomph or for an electric hot water heater, get one. Then add a minor amount of solar to keep up with the small daily loads. But.... you do want to run that generator once a week or so to keep it in good shape.

To me, this is the ideal setup. Redundancy, not fully depending on the generator and not as expensive as 100% solar.

As to sail vs power for traveling, I'm still saving up for a mast and sails. $48,000 was the quote on that. Would be a lot cheaper just to motor everywhere. $48,000 for an aluminum stick, cruising sails and that's it. Doesn't include winches, running rigging, etc.

[valhalla360]

Originally Posted by pwillems

Seems the concensus is pretty overwhelming for solar/wind. But how about from a cost perspective?

Panels + controller + mounts + etc... ~$5k (guessing, definitely have not priced it properly)
Wind generator + controller + mount + etc... ~$5k
High efficiency DC watermaker ~$15k
Extra batteries ~$2k

vs

Aquagen DC genset with 210A alternator and 40GPH engine driven watermaker: $10,998
Installation: $500 (I already have an AC genset that I am removing, so installation costs will be minimal).

That's $15.5k less for the genset option. Sure, the genset will require fuel, but for $15.5k, I can make a heck of a lot of amps each week and still be ahead for many years to come.

There is also the flexibility of power on demand... guests over late for some sundowners and want some ice for their drinks? Just run the generator an extra hour the following day to recover. Can't do that with renewables.

Again, just talking out of my hat here, I am only planning at this stage, those out there doing it right will know more about this than I do.

Few things:
- Do the energy audit first. You are building a system when you don't know what you need.
- I think your installation costs are high unless you just give an installer a blank check.

[a64pilot]

I can't see a case for a DC genset, I started that way myself, but couldn't make the "numbers" work.
In today's world AC and DC are pretty much interchangeable, yes there are conversion losses, but they are small, and AC generators are the industry standard, which means more of them are available and at a lower cost, and your big loads are usually AC or can easily be AC.
As has been said, water heating, Air conditioning, Ice making, water making,clothes washers, wifes hair driers, curling irons, straitening irons etc are often AC, DC ones are available, usually for a higher price and limited availability.

By all means go with as much Solar as you can, but I have it from a couple of experts that you just can't quite get a lead acid bank to 100% full charge with Solar, just not enough hours in the day, if that is true, then to keep your bank healthy you need supplemental power from somewhere, shore power is fine, or a generator.
Since we now have a generator and plan on running it a couple times a week for battery health, why not have a less expensive AC watermaker, ice maker, clothes washer and wash clothes, make water, charge batteries and make ice and any other energy intensive tasks you have while the generator is running.
Smallest generator Nexgen makes will handle all the above, and is less expensive than a DC generator and DC watermaker.

Now if you have a bank that does not require being recharged to 100% very often, then of course that may skew the whole supposition, then you may be able to go all renewable and stay there.

I've not left yet, so all what I have done is pure theoretical at this stage, but I have 750W Solar and the Nexgen generator, and a large alternator on a serpentine belt.
Solar should be able to run the boat, generator will be needed for high current things, watermaker, ice making, clothes washing, Air conditioniong if desired etc.
However to a reduced capacity the alternator can run all the above if the generator dies or we happen to be motoring somewhere.


With just a little shopping around, the Nexgen is about $5,000, a good, no great AC water maker, another $5,000

[valhalla360]

Originally Posted by a64pilot

I can't see a case for a DC genset, I started that way myself, but couldn't make the "numbers" work.
In today's world AC and DC are pretty much interchangeable, yes there are conversion losses, but they are small, and AC generators are the industry standard, which means more of them are available and at a lower cost, and your big loads are usually AC or can easily be AC.
As has been said, water heating, Air conditioning, Ice making, water making,clothes washers, wifes hair driers, curling irons, straitening irons etc are often AC, DC ones are available, usually for a higher price and limited availability.

By all means go with as much Solar as you can, but I have it from a couple of experts that you just can't quite get a lead acid bank to 100% full charge with Solar, just not enough hours in the day, if that is true, then to keep your bank healthy you need supplemental power from somewhere, shore power is fine, or a generator.
Since we now have a generator and plan on running it a couple times a week for battery health, why not have a less expensive AC watermaker, ice maker, clothes washer and wash clothes, make water, charge batteries and make ice and any other energy intensive tasks you have while the generator is running.
Smallest generator Nexgen makes will handle all the above, and is less expensive than a DC generator and DC watermaker.

Now if you have a bank that does not require being recharged to 100% very often, then of course that may skew the whole supposition, then you may be able to go all renewable and stay there.

I've not left yet, so all what I have done is pure theoretical at this stage, but I have 750W Solar and the Nexgen generator, and a large alternator on a serpentine belt.
Solar should be able to run the boat, generator will be needed for high current things, watermaker, ice making, clothes washing, Air conditioniong if desired etc.
However to a reduced capacity the alternator can run all the above if the generator dies or we happen to be motoring somewhere.


With just a little shopping around, the Nexgen is about $5,000, a good, no great AC water maker, another $5,000

I agree, no need to mess around with oddball DC generators. Stick to standards will make it easier to find maintenance and parts.

I disagree on solar being less likely to get you to 100% charge. A generator runs into the same issue. The last 5-10% the batteries accept charge very slowly, so your generator is still burning lots of fuel but not much is going into the batteries. Most people give up around 90% and accept they won't hit 100%.

If you size your solar at 1.5 to 2.0 times your daily consumption to catch up after a cloudy day, most of the time, the bulk charging gets done by noon/1pm and then then you have 3-4 hrs of charge trickling in to top it up. At least that's what we see.

[sailorboy1]

I don't feel you really can beat the combo of solar and a diesel generator on a boat for flexibility etc.

I have 290W solar, which has pretty much kept up with my power needs the past 3 years. But since I'm heading out this year I decided we needed more power and didn't want to have to use the main engine for this. So I ordered a 4KW diesel generator AC unit. This is to run the watermaker, air conditioner if needed, heaters if needed. hot water heater etc.

I figure that just running it for hot water and making water that I will charge my batteries at the same time, so I'm not increasing my solar and turning my boat into an aircraft carrier.

BTW - when I added up the costs involved in having a water maker and heat, getting a diesel generator became less expensive than increasing solar and getting the same things.

[malbert73]

Seems like running engine or generator in AM for 30-60 min to bulk charge, and then solar to float to full, is ideal setup if you don't have enough solar or for cloudy days. C/w cruising where you are motoring out of harbor in AM, or topping water tanks, heating water, making ice, etc. so agree solar + genset is ideal.



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[Kenomac]

Originally Posted by sailorboy1

I don't feel you really can beat the combo of solar and a diesel generator on a boat for flexibility etc.

But since I'm heading out this year I decided we needed more power and didn't want to have to use the main engine for this. So I ordered a 4KW diesel generator AC unit.

BTW - when I added up the costs involved in having a water maker and heat, getting a diesel generator became less expensive than increasing solar and getting the same things.

Just curious, how much was the final cost to purchase and install the generator and where did you locate it on your boat? A diesel generator is a great investment which will come in very handy.

What model watermaker did you end up buying?

Once agian, I'm considering the addition of a few solar panels on the Bimini to top off our battery bank.

[a64pilot]

Originally Posted by malbert73

Seems like running engine or generator in AM for 30-60 min to bulk charge, and then solar to float to full, is ideal setup if you don't have enough solar or for cloudy days. C/w cruising where you are motoring out of harbor in AM, or topping water tanks, heating water, making ice, etc. so agree solar + genset is ideal.



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That is the idea, make water, bulk charge the batteries in the AM and by the time Solar is really working well turn the generator off, your batteries are close to being fully charged and you use Solar to trickle in that last 10% or so, not Diesel.

I have a gut feeling that if in fact you just can't get to 100% full charge on Solar alone, then why should your controller ever get to float? I think if your going into float, you may be doing so prematurely

[Cheechako]

This: or this:. Your choice.

[Dsanduril]

Pictures are so much easier

This:

Fort Holland 138 Farm Tract Sounds

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Vancouver Waterfront Park Lapping Waves Seagulls Distant Sounds

?

[socaldmax]

Originally Posted by a64pilot

By all means go with as much Solar as you can, but I have it from a couple of experts that you just can't quite get a lead acid bank to 100% full charge with Solar, just not enough hours in the day, if that is true, then to keep your bank healthy you need supplemental power from somewhere, shore power is fine, or a generator.

I think your friend is right, but not because of the hours of sunlight, but because none of the charge controllers are designed to hold absorption for long enough. I'm not aware of a single model that allows you to extend absorption beyond 3 hrs. A lot of them switch to float as soon as absorption voltage is reached.

The same goes for most battery chargers. I say most because I don't know of any that are fully programmable, but I haven't seen them all, so I'm hoping there's one out there. That's why I added an ice maker to use the solar power and extend the charge time instead of seeing my solar charger switch from absorption to float at 11am.

I'd love to find a solar controller and battery charger that would actually fully charge batteries, but since the solar recharge cycle starts up again at 8am every morning, maybe being 100% charged isn't such a big hairy deal after all.

That's the beauty of having a lot of solar. During the day, it powers everything, including battery charging. At night, the batteries only have to handle whatever loads you put on them until the solar takes over again at sunrise.

Install a lot of solar, a battery bank slightly larger than the numbers indicate, and you're floating around between 60-95% charge all of the time. No real harm to the batteries so they last a long time, plenty of reserve power in case you need it and most (if not all) of the comforts of home. I'm also a fan of the Honda 2000, if you need a little extra juice without firing up the big generator.

[socaldmax]

Originally Posted by malbert73

Seems like running engine or generator in AM for 30-60 min to bulk charge, and then solar to float to full, is ideal setup if you don't have enough solar or for cloudy days. C/w cruising where you are motoring out of harbor in AM, or topping water tanks, heating water, making ice, etc. so agree solar + genset is ideal.



Sent from my iPad using Cruisers Sailing Forum

That's what I do with my trailer. I run the gen for 30-45 min in the morning to power the microwave, coffee pot, toaster, start the ice maker, etc. It also runs 115ah of battery charger, so maybe 60 - 80A get put into the batteries during that time. I also run it for about 1/2 hr at dinner time for the microwave and a little extra into the batteries after the sun goes down. The evening battery charge isn't necessary, but the genny is running anyways.

[socaldmax]

Someone mentioned hot water...

I've been toying with the idea of a solar water heater. Since I'm interested in a catamaran, I was thinking of laying a panel of solar water heater on the cabin roof, with an insulating blanket behind it. That should provide plenty of free hot water during daylight hrs.

[valhalla360]

Originally Posted by socaldmax

Someone mentioned hot water...

I've been toying with the idea of a solar water heater. Since I'm interested in a catamaran, I was thinking of laying a panel of solar water heater on the cabin roof, with an insulating blanket behind it. That should provide plenty of free hot water during daylight hrs.

I know it's the poor mans option but we have a solar shower, which is basically a 5 gal black plastic bag with a hose. On a sunny day, it gets the water plenty warm.

If you have the deck space, it wouldn't be hard to install a small swimming pool style heater and a circulating system. Keep the circulating pump as low of amperage as possible and maybe a timer so it circulates 1 minute out of 5 and it would be much more efficient that simply converting electricity to heat.