Solar Upgrade verse Running the Generator

[Exile]

Originally Posted by john61ct

It is IMO just silly to incorporate high-consuming systems designed for incredibly cheap shore power, into designs for mobile applications relying on very expensive low-voltage DC power.

Some very wealthy boaters pay out the wazoo for dishwashers, walk-in freezers, electric hair dryers, ovens and induction cookers, even air conditioning! while living off battery power.

But that doesn't make it any less silly in my book.

Unless you are very power conserving, or running the genset for hours every day anyway, IMO it is always a good investment to maximize solar panels, available space and aesthetic issues are the limiting gactors, never cash cost.

Either that or just run such energy-intensive appliances off your relatively cheap AC genset directly while also using it to charge batts. and/or make water much faster & more efficiently than you could with a 12v watermaker. This might help answer or at least inform sailor boy's question depending on what appliances he has onboard.

What I'm dealing with is a boat that already had a very well functioning (Seafrost) 110v fridge & freezer when I bought it, and an 8k genset. So the reality is when I'm not motoring I generally need to fire the genset up for refrigeration long before I need to charge my batts. So my batts. typically never go under 70-75% SOC. I'm probably better off with 12v refrigeration, but I have a large deep freeze and I keep reading that freezers, water heaters, aircon & the like are the "tipping point" for needing to supplement with 12v/solar/etc. with AC gensets.

But we can start a new thread on this if it's not helping sailorboy out.

[john61ct]

Yes, your system is designed so that you must use the genset very regularly.

My preference is one where that is only needed when the weather conditions require it, or high-maintenance guests are aboard, etc.

Ideally as things improve genset runtime is constantly reduced, until it's only needed very rarely.

[sailorboy1]

Originally Posted by Exile

But we can start a new thread on this if it's not helping sailorboy out.

It's not really a matter of helping me out, it's just a thinking topic. I WANT the solar, but the logical part of me says it is a waste of money (not a waste really but a poor payback use).

In the end what it comes down to is: Is it worth spending $500 because the current solar falls 40 AH/day short of charging the batteries, or does it make more sense to run the generator every day or to make up the shortage (and make hot water and do whatever else is needed for AC power)?

BTW - a 70% SOC would be very rare on my boat currently. I'm trying to actually learn to allow my batteries to get that low more often as I figure it's only going to cost $60-80/year.

[zboss]

Personally, I think a diesel generator with significant tankage, high output Alts, and lithium batteries is the most appealing energy solution. If I had room for a diesel generator I would ditch 1/2 my solar panels and the wind generator.

As it is, I have a large alternator tied to my he engine and am planning on buying lithium. At which time I will ditch the Honda generator and make do with my existing 165 amp alt and existing spare alt.

[john61ct]

Running the genny **in the morning** is the only way to help get the bank to 100% full.

I assume your bank is expensive enough that doing so is important to you.

If these daily morning runs are convenient for you for other reasons anyway, then yes, you can do without more solar.

But if you need to add runtime to the genny **for just charging**, then more solar allowing you to reduce that is a good investment.

[Exile]

Originally Posted by sailorboy1

It's not really a matter of helping me out, it's just a thinking topic. I WANT the solar, but the logical part of me says it is a waste of money (not a waste really but a poor payback use).

In the end what it comes down to is: Is it worth spending $500 because the current solar falls 40 AH/day short of charging the batteries, or does it make more sense to run the generator every day or to make up the shortage (and make hot water and do whatever else is needed for AC power)?

BTW - a 70% SOC would be very rare on my boat currently. I'm trying to actually learn to allow my batteries to get that low more often as I figure it's only going to cost $60-80/year.

Personally, and if I was out cruising all the time & rarely at the dock which sounds like your scenario, I would love to be another $500 away from only having to use my genset on rare occasions. Then again, and if my math is right, $500 worth of diesel if your genset uses 0.25/gal. per hour buys you close to 700 hrs. of run time (not incl. maint.). Depending on much you're motoring, that's a LOT of time w/o having to refuel! But given how close you are, I would probably still spend the bucks on the added solar for the added independence it affords, but that's just me. I suppose part of it is that, once you add the solar you're pretty much done, whereas the genset could always quit running. May also depend on how many AC-only appliances you have & how you or the missus feel about having to do without, and whether you're contemplating a 12v or 110v watermaker down the road. Obviously having a heat exchanger on the h/w heater helps out if/when you run the engine.

Sounds like you already got it, i.e. yet another boat decision that makes little sense financially but you can always find good reasons to do it anyway.

[john61ct]

Fuel cost is a fraction of the total per-hour cost of run time.

[Exile]

Originally Posted by john61ct

Fuel cost is a fraction of the total per-hour cost of run time.

For sailorboy the financial analysis would then come down to how much of the $500 he's not spending on add'l solar will likely be spent on genset maint. vs. fuel. It sounds like he does most of his own maint., so in 700 hours we're talking maybe the cost in parts for 7 oil/filter changes (or 3-4 if a 200 hr. interval), along with ??? depending . . . . A gal. of Rotella is $12-13 at Walmart, and oil/fuel/Racor filters are not expensive. YMMV obviously, but if reasonable preventative maint. is done, modern diesel gensets tend to run a long time w/o significant maint. issues. Unlike a propulsion engine, I've read that 20,000 hrs. is not that unusual.

But you're saying that, in this scenario anyway, fuel cost is only a fraction of total per-hour cost of running a genset for the next 700 hours?

[Exile]

Originally Posted by zboss

Personally, I think a diesel generator with significant tankage, high output Alts, and lithium batteries is the most appealing energy solution. If I had room for a diesel generator I would ditch 1/2 my solar panels and the wind generator.

As it is, I have a large alternator tied to my he engine and am planning on buying lithium. At which time I will ditch the Honda generator and make do with my existing 165 amp alt and existing spare alt.

How are your solar panels & wind gen coming up short? Does the much higher up front cost of lithium pay off with add'l durability?

Btw, I just ran across a link to an adapter some co. is making to allow the Honda 2000 to run off propane. Makes it quite a bit more attractive, assuming you already have propane onboard for cooking, etc.

[john61ct]

Well even a majority is still a fraction innit?

In the abstract, the installed price of the genset divided by lifetime hours needs to be added to maintenance and consumables.

In this case the purchase is a sunk cost, so OP likely just looks at incremental.

However for me, the external cost of noise is not an insignificant issue.

And some may think it foolish, but guilt over the issue of fossil fuels would lead me to some financial sacrifice to feel I'm at least trying.

[Exile]

Originally Posted by john61ct

Well even a majority is still a fraction innit?

Not the way you stated it!

In the abstract, the installed price of the genset divided by lifetime hours needs to be added to maintenance and consumables.

And to do a fair comparison, the installed price of the solar panels, wiring, controllers, frames/arches, battery upgrades, and inverters (good ones are $$$!!) must be considered as well. Even a large, premium solar set-up likely wins handily over a diesel genset on initial costs, but some panels have a shorter lifespan than others, whereas gensets can outlast the boat. And then you probably should add in wind gens for when the sun's not shining but the wind's blowing, and hydro for when the wind gen's not working because you're going downwind and the solar's not working because it's cloudy, nighttime, or the boom is shading it, etc., etc. You get where I'm going . . . .

In this case the purchase is a sunk cost, so OP likely just looks at incremental.

Not sure how that fits into the financial analysis presented by the OP's two choices. He can spend nothing up front now and incur what will likely be the minimal costs of running his genset more, or he can outlay $500 now and save the minimal expense of running that same genset less. I think the financials clearly weigh against more solar, but there are other positive factors that weigh in its favor nonetheless.

However for me, the external cost of noise is not an insignificant issue.

Agreed, but at least with mine it's only a problem for those down below while it's running for an hour or two per day, and not for anyone up on deck or on another boat. And the cabin noise is mainly because it lacks an enclosure which I think most of them ordinarily come with or can be added. (no room on mine).

And some may think it foolish, but guilt over the issue of fossil fuels would lead me to some financial sacrifice to feel I'm at least trying.

There are many valid reasons more worthwhile than guilt to go in your direction, particularly on a cruising sailboat. It's only foolish if you think, as I believe many do, that solar/wind/hydro amounts to "free energy" that wins hands-down over fossil fuels. As I've said, I would love to be in the OP's position right now with my boat, but the reality is that it would likely cost a fortune to get there -- and would frankly be rather wasteful -- the way my boat is set up now. But if environmental guilt is a factor, you should probably also contemplate all the fossil fuels that went into producing your solar array, to say nothing of your boat itself, as well as the disposal issues. Not suggesting a diesel genset is an environmentally friendly device, but it does produce a lot of energy in a short period of time and thus does so very efficiently.

[daletournier]

Originally Posted by john61ct

Actually that's ideal, since your design should be based on a few overcast days in a row, still getting the bank to full.

A holding plate fridge is another good excess power load dump.

This is a good point. You don't need more when the sunshines everyday, its when the sun isnt at its best. My 480w is more than enough at anchor when the sun is on. Enough solar will take care of you on the overcast days within reason, I'm adding another 250w for just this reason.
Also being at anchor is different than multiple day passages . Passages are brutal on batteries, you'll appreciate the generator and more solar.

[john61ct]

Yes.

But load devices are not part of the power generation side of the picture, much less inverters.

My ideal design would be none of those, but if a strictly necessary appliance required one, that's a cost added to buying that appliance.

[Kenomac]

Originally Posted by john61ct

It is IMO just silly to incorporate high-consuming systems designed for incredibly cheap shore power, into designs for mobile applications relying on very expensive low-voltage DC power.

Some very wealthy boaters pay out the wazoo for dishwashers, walk-in freezers, electric hair dryers, ovens and induction cookers, even air conditioning! while living off battery power.

But that doesn't make it any less silly in my book.

Unless you are very power conserving, or running the genset for hours every day anyway, IMO it is always a good investment to maximize solar panels, available space and aesthetic issues are the limiting gactors, never cash cost.

Induction cooktops cost around $80 and use very little energy to cook food. How do you propose cooking food in a more cheaply or more eco manner, and.... without searching for and lugging tanks of propane or butane around?

These things (NuWave) are the best thing since sliced bread in the kitchen.

[daletournier]

Originally Posted by Kenomac

I have a 230v 1500w inverter I can dedicate to the waterheater. So next season, I plan to plug it in full-time to see if the extra solar capacity can keep the water warm all day following an initial warm up using the generator or engine. I first need to install a selector switch on the 230v side for panel vs inverter. The waterheater is 230v., but I'm finding that during the day the solar is producing a steady 20-22amps, but the batteries are only able to accept 2-7amps since the batteries usually begin the day at 86% and end at 95-99%. There seems to be extra unused capacity.

I'm currently at day four without touching the generator and the battery bank is at 82-86% in the morning then coming up to 95-99% by sunset on 450w of solar alone. All I'm using at anchor is interior LED lighting, a fridge, water pump, microwave, two watermakers, on-demand coffee machine, NuWave induction cooktop and electric toilets. No big screen TV or deep freezer.

What size is the water heater element? It will be a large draw on a 400amp? battery bank.