How Much Solar

[sailorboy1]

Originally Posted by Ex-Calif

To Don, Azul and tusharks - I get the idea that you want "simple" answers. Unfortunately simple answers can often be incorrect.

Since I didn't ask anything other than how much solar do you have and is it enough, which is a very simple questions, why can not I get a simple answer?

It isn't like I asked how much solar do I need etc.

[Ex-Calif]

Don - You know enough about how this place works to expect any simple answer.

Azul and Tusharks expanded your "simple" question and the thread drifts.

Quite honestly your questions (you also asked what people's loads were) makes little sense but since you asked...

40w
enough
~30amps a week

[sailorboy1]

The question makes sense if you consider it as just how much loads you have compared to how much solar you have, and does the solar keep up.

I fail to see how this doesn't make sense as a real world question.

I don't understand why we always feel the need to see how complicated we need to make answers.

[denverd0n]

Originally Posted by Don Lucas

I fail to see how this doesn't make sense as a real world question.

It doesn't make sense because it is not useful information. I guess if you just want to know if everyone else is happy with their system or not, it's okay. But if you want to actually DO anything with the information then (and honestly, no offense intended), direct and simple answers to the question you asked are going to be useless at best, and misleading and counter-productive at worst.

Like it or not, this is not a subject that can be meaningfully reduced to "simple" answers. Any "simple" approach to this is almost certain to result in one of two things: 1) a system that does not meet needs, or 2) a system that exceeds needs and thereby costs more than it had to.

(And I put "simple" in quotes above because, once again, the math needed to do this the right way is nothing more than basic addition and multiplication. It's fourth grade kind of stuff. The "complicated" way really is pretty simple!)

[LakeSuperior]

IMHO complexity is in the eye of the beholder. This is pretty simple stuff to an electrical engineer. To an person untrained in electrical engineering it may appear daunting. In fact, to the untrained, in many cases they don't know what they don't know (seemingly simple problem that is not.)

Consequently, precise communication needed to solve what appears on the surface to an untrained sailor (a person uneducated in basic electrical engineering) to be a simple problem will seem complicated. Only the statment of the problem is simple.

Consider that many smart CF posters are not purposely trying to give complicated answers as you have insinuated.

It is a complex world...there aren't always simple answers if you desire a good outcome.

[denverd0n]

Originally Posted by LakeSuperior

This is pretty simple stuff to an electrical engineer.

I'm not an electrical engineer. I did learn simple algebra in grade school, though, and that's all this is.

watts = volts x amps

That's it. That is as complicated as it gets. If you can remember that one formula, and do simple algebra, then you can figure out everything you need to know to outfit yourself with an effective and efficient solar-charged electrical system.

How much simpler can it get?

[Mr B]

Originally Posted by Don Lucas

Since I didn't ask anything other than how much solar do you have and is it enough, which is a very simple questions, why can not I get a simple answer?

It isn't like I asked how much solar do I need etc.

4 panels, 2 X 85, 2 X 50 Rutland 913 Wind generator, 4 X 85 AH house batterys, I have a gas fridge and stove, hot water comes from the Engine, about 20 minutes is ample for 2 showers and hot water for the sink, It also pumps up the batterys when its running,

Every thing else is electrical, Water maker every 3rd day, 60 gallons,

I ran out of water and batterys, when I first moved onto the boat, but soon worked out you cant leave everything on, including nav lights,
And the Dunny was using freshwater to flush,

It is totally self sufficient now I know its limitations, I still run most things continously,
I dont run out even in the cold weather, cold weather down here means no sun at all,

I dont have a battery charger, I dont have a Honda generator, Etc, And I dont need shore power,
Thats living on the boat full time for nearly 3 months, 7 weeks with 2 people on board.

[LakeSuperior]

Originally Posted by denverd0n

I'm not an electrical engineer. I did learn simple algebra in grade school, though, and that's all this is.

watts = volts x amps

That's it. That is as complicated as it gets. If you can remember that one formula, and do simple algebra, then you can figure out everything you need to know to outfit yourself with an effective and efficient solar-charged electrical system.

How much simpler can it get?

True enough. I was using the electrical engineer to clearly illustrate the point.

Consider that it can get sticky when you consider the the duty cycles over the operating modes, at anchor versus passaging. Battery acceptance rates, matching solar, wind, and generator outputs to consumption cycles. Specifying the right hardware for the job...not too little and not to much but just right (cost/benefit). Think cost of 12 kw versus 6 kw generator, which one do I need. Must consider safety margins...what is worst case so the batteries don't go below 80%.

Are you confident enough to spend $XXXX of your money on a system of your design? Did you miss anything?

The harder part is figuring out what the numbers are to put into the simple math.

[Mr B]

Originally Posted by Jimbo485

We have 970 W of solar panels, 880 Ah of wet cell bateries, Link 10 Monitor, no generator, a little 6A alternator on 1 outboard, no wind generator, mostly all LEDs, no electric anchor winch, no electric pumps apart from the watermaker, a fridge that can also freeze (because I threw out the thermostat), 1500 W inverter, a 12V computer, a flat LED screen with 12V - 18V transformer.

No problem. Had 40+ A pumping into the system today before I started shutting panels down.

Panels are so cheap these days that it is cheaper to buy more panels than to buy an MPPT controller. As long as you have enough real estate on deck to install the panels!

Our boat originally had 340 W of panels which still run thru the original controller. The additional 630 W runs direct to the batteries and I control them thru breakers in the cockpit. Shock, horror! No controller, no MPPT for them! Just common sense and attention. We live onboard full time and in the cockpit I can see the battery bank voltage and flick the panels on and off depending on what is necessary. Super simple. If we leave the boat, our loads decrease and I turn off some or all of the 630 W of additional panels and let the old 340 W panels and the controller look after everything.

Our 880 Ah of batteries cost about a grand. The additional 630 W of panels also cost a grand in 2010. We don't spend anything more on fuel, oil changes, controllers, MPPT (the only way to justify that scam is if you simply can't fit more panels on your boat) and we don't do the 1 hour of generator noise in the morning followed by another hour at night.

KISS!

Where are you down under and where did you get your batterys from, I need to buy new ones and those prices are cheap from the prices I have got so far,
And what sort of batterys are they as well,

[Azul]

Originally Posted by LakeSuperior

IMHO complexity is in the eye of the beholder. This is pretty simple stuff to an electrical engineer. To an person untrained in electrical engineering it may appear daunting. In fact, to the untrained, in many cases they don't know what they don't know (seemingly simple problem that is not.)

Consequently, precise communication needed to solve what appears on the surface to an untrained sailor (a person uneducated in basic electrical engineering) to be a simple problem will seem complicated. Only the statment of the problem is simple.

Consider that many smart CF posters are not purposely trying to give complicated answers as you have insinuated.

It is a complex world...there aren't always simple answers if you desire a good outcome.

This shows a good understanding of what is going on in this thread. It is very true that a topic that seems simple to you (if you already know the topic well) may be gibberish to someone that isn't initiated. Having a system that doesn't meet your needs is a problem, and like everything else on a (my anyway) boat one should understand the system or ultimately it will cause pain/excess expense etc. I doubt that anyone is going to find it a problem to have excess solar capacity, they will just find more items that become "necessities."

Sometimes the cognoscenti also forget that a newish sailboat owner isn't usually faced with one system to figure out, they may have dozens of projects each crying out for time/money/understanding simultaneously. To this person, a patronizing tone is not welcome.

Don, it is my fault that I expanded your simple question. I thought you were trying to help people get started in solar by providing some examples of real world systems that people are happy with and should have just kept reading or started a new thread. For many people, I think the topic has been made so daunting they will continue to run their diesel or a Honda generator to charge their batteries. My new to me boat is currently hooked up to shore power, next week I have to move it 300 miles down the ICW and I have no way to monitor the batteries yet, am not sure whether the alternator works or not (yes I read everything I could find about how to test this and may have only succeeded in actually frying the alternator ha) and now if I run my two new deep cycle batteries down on the trip and can't start the engine... Still, life is good because I have cheap waterfront property and only two fixed monthly bills totaling $39.

[LakeSuperior]

Originally Posted by Azul

Sometimes the cognoscenti also forget that a newish sailboat owner isn't usually faced with one system to figure out, they may have dozens of projects each crying out for time/money/understanding simultaneously. To this person, a patronizing tone is not welcome.

This statement doesn't seem to gype with your earlier post requesting for a simple upgradable solar system design.

[noelex 77]

Originally Posted by Azul

This shows a good understanding of what is going on in this thread. It is very true that a topic that seems simple to you (if you already know the topic well) may be gibberish to someone that isn't initiated. Having a system that doesn't meet your needs is a problem, and like everything else on a (my anyway) boat one should understand the system or ultimately it will cause pain/excess expense etc. I doubt that anyone is going to find it a problem to have excess solar capacity, they will just find more items that become "necessities."

Sometimes the cognoscenti also forget that a newish sailboat owner isn't usually faced with one system to figure out, they may have dozens of projects each crying out for time/money/understanding simultaneously. To this person, a patronizing tone is not welcome.

Don, it is my fault that I expanded your simple question. I thought you were trying to help people get started in solar by providing some examples of real world systems that people are happy with and should have just kept reading or started a new thread. For many people, I think the topic has been made so daunting they will continue to run their diesel or a Honda generator to charge their batteries. My new to me boat is currently hooked up to shore power, next week I have to move it 300 miles down the ICW and I have no way to monitor the batteries yet, am not sure whether the alternator works or not (yes I read everything I could find about how to test this and may have only succeeded in actually frying the alternator ha) and now if I run my two new deep cycle batteries down on the trip and can't start the engine... Still, life is good because I have cheap waterfront property and only two fixed monthly bills totaling $39.

I still think its complicated.

It is a bit OT but if Don does not mind a brief answer.( a new thread is usually the best way for new topics like this)
A simple test and crude test for the alternator is to turn off shore power and start the engine with multimeter probes on the battery. If the voltage rises you know the alternator is at least putting out something.
A clamp on multimeter is a great bit of gear and will tell you how many amps the alternator is putting out, which is a better quantitative test.

[Maine Sail]

Don,

Knowing your boat is on a mooring I will give you a run down of how I size for mooring re-charge systems. If you want larger for "cruising" then you'd need to go larger.

For mooring charging I size like this:

Ideally you want the alternator, or generator, to handle "bulk" and some absorption charging and bring the bank back to 80-85% state of charge. From there you can let the solar panel do the rest and bring the bank back to 100% SOC, when you're not there during the weekdays.

If you want to satisfy cruising needs such as refrigeration, instruments, AP etc. then your array can get quite large. You did not specify so I will give an example of hos I size for a mooring re-charge.

The faster you can bring the bank from less than 100% to 100% the less sulfation you will have and as a result the longer battery life you'll get.

I'll use an example of a bank of 300 Ah's for a "mooring recharge".

The last 20% of capacity of a 300Ah bank is 60 Ah's. However, you ideally need to take charge inefficiencies into account too so you'll really need to put back in about 70Ah's +/- to get back to that elusive 100% state of charge that boats on moorings need.

For moored boats the panels are usually left flat when you're not there so that you can capture "most" of the sun. In a land based solar array the panels are fixed, the property is not moving like a boat does, and can be angled at the sun for the best performance. For this reason alone land based solar calculations rarely if ever apply or translate well to boats. On boats the panels are rarely oriented at the sun for optimum solar gains and the stick, rigging and other appendages get in the way on swings or at different times of the day causing shading which can drastically limit array performance..

Having the ability to "aim" the panels at the sun, on a boat, is not usually a workable solution when swinging on a mooring, or at anchor if cruising unless you are there or are attentive to it, so, panel position is very often a compromise and most leave them flat.

If you are at a dock you can rig the panels and aim them more appropriately but not on a mooring, like you are, or off cruising where your boat will swing at will unless you pay really good attention or the wind & tide always come from the same direction, not so with 10+ foot tides... If you might someday wind up at a dock then articulating panels can help the output.

Because of these aiming restrictions I find, after lots of monitoring here in the North East, you can figure on about 3.5 - 4.5 hours of full rated output per day on average. In the summer our insolation numbers are actually pretty good up here.

Some folks use 5 hours per day in the Northeast but after lots of monitoring of my own panels, and customers, I found that to be a little to generous. Some days it will be more some less but here in Maine 3.5 - 4.5 hours at full output, is an average sizing number that seems to work best.

So, a 300 Ah bank @ 20% down = 60 Ah's that need to be returned + charge inefficiency = 70 Ah's total needed for a "full" bank. Note that I don't care what your load calculations are because you are doing this with no loads, when you;re not even there, other than some parasitic loads. if you were a live abord this would be different but I don't think you are as you live in Merrimack, NH which is about an hour to your boat..

A 2.5A output panel X 4.5 hours = roughly 12.5 Ah's/Day returned to the bank. If you have phantom/parasitic loads, like a propane sniffer or other "always on" loads, subtract those and this is your "net" average/day.

Next divide 70 amp hours (or what ever your bank is) by 12.5 and you can see that it will take approximately 5.6 days to go from 80% SOC to full on a 300 Ah bank with a panel capable of 2.5A. This is in PERFECT conditions though.

I personally feel that's a little long, especially accounting for weather, so would prefer to see a panel in the 3.5A minimum range on the example 300Ah bank. Bigger is always better but this becomes a "real estate", budget and let's admit it, an aesthetic compromise with many boats and boat owners. A 3.5A panel shaves a full day off the time it takes to hit full when compared to a 2.5A panel, 4.5A faster yet and a 7.5A panel you're full in just about two days from where the alternator stopped..

For cruising figure the maximum amount of time you want to run the engine or gen set per day, or every other day, then base your array size on the difference needing to be made up while accounting for loads. If you only want to run your engine for an hour per day, when you hit 50% SOC, and your alternator can get you from 50% to 70% in an hour then you have a 30% deficit to make up plus charge inefficiencies. You can size your panel to make up this deficiency if you know your average loads, which you do. There are always worst case and best case scenarios too and a best case is not always going to happen..

For your bank I would think a single 140W Kyocera, or other comparable panel, (AltE has great prices, are in Webster, MA and can ship one to Maine UPS for $23.00 in one day at ground rates BTW) would be a good base to start with. Going with two 140W panels would be really nice but a single 140W should top you up fine during the week. I just ordered two Kyocera 140's last week from AltE and they were here the next day (with ground shipping) for short money and it they are a premium panel..

It's all in what you want the system to do and you really did not specify, so I answered with what most boaters here in Maine want to do with mooring stored vessels, and that is get the banks back to full, within a few days, from about 80% SOC...

I'll pre-duck now to avoid Don's lecture on why my input may not have been appropriate to his original question...

[sailorboy1]

No need to duck!!! Of course I never said my goal was to recharge my batteries while on my mooring while gone for the week (I never asked for any sizing help at all. But thanks, really because I know threads get used by others in lots of ways,not trying to be an a-hole)

I am an engineer and already fully understand how to size my system and was really just looking for what people in real were using, not how to size my system. Pretty basic math etc.

Now I expect all the smart CF experts to start telling me how stupid I am even though all I asked is what they were using.

PS - I figure the chances of keeping the thread from going down the system sizing cals are long gone. So for those that what to do so, go ahead but there isn't any need to address it to me personally. To others that just want to answer the question in terms of: I have 360W solar, 100AH daily loads, feel my solar is enough - thanks)

[Azul]

Originally Posted by LakeSuperior

This statement doesn't seem to gype with your earlier post requesting for a simple upgradable solar system design.

I think you just want to argue? I made it quite clear I have a time issue, not to mention temporary budget issues. Once I get to Beaufort I will have ample time to figure this topic out on my own.

Don, I love reading your posts. They often make me laugh, and you are so NOT pretentious which is refreshing! Noelex77 and a few others, I have benefited from reading your posts which illuminate just how complex the finer points of this subject are.