Here's a good little exercise I have to go through on my boat that maybe everyone can help out on. This subject, I am not 100% familiar with, so maybe between us all, we can figure it out.

I'm looking into a new Honda genset, OR... the thought occurred to me that for the same (or similar) money, I could just grab another couple solar panels!

The only way to know if the solar panels will work is to figure out the system. Anyone want to do that with me?

Here are the facts:

*I have plenty of existing solar (and wind) generating capacity.
*I have situations in the damn fog and rain up here in the northeast USA where I go for an entire week without seeing the sun (one of those is coming up again this week)
*I am doing a great deal of online work since chartering didn't work out. This takes up to 40AH per day or so running computers, networking devices, etc...
*I have a freezer and refrigerator that take up another 50 amps per day when it's hot out.
*I can sustain my power consumption no problem when it's sunny out, or if the winds are in the 15-20 knot (sustained) range

Here is the current setup:

*6 Trojan batteries providing a rounded down 600AH bank
*1 Air-X Wind Generator, with internal charge regulation, tied directly to batter bank (through proper fuses, etc...)
*2 BP Solar 3125J panels (125 watts each)
*1 Xantrex c35 Solar Charge Controller
*Link 10 Battery Monitor this is how I know my battery state of charge.

I don't have hard numbers on my consumption because the system worked fine in FL where I bought the boat. I only ran into issues one time in FL on some particularly rainy week when the temps were in the high 90's and I started to run low on battery reserves from the refrigerator and freezer running constantly to keep up.

Most other times it was fine. It's also fine up North because the temperatures are more moderate up here. The refrigerator and freezer don't run very often in these temps. However, there are more times that I end up in a deficit because of my heavy computer usage combined with seriously cloudy/foggy/rainy crappy days.

I need just that little extra kick to make up for all this computer use that the electrical system wasn't designed to take into account. Plus, a little microwaving of leftovers here and there (20 AH?) would be nice.

NOW... I need to figure out if the extra solar panels will keep me ahead of my consumption on these cloudy/rainy days, what will be required for the installation of extra panels and what the cost will be compared to a Honda genset both now and over time.

1) What are some of the best solar panels out there in terms of $ per Watt? I was looking at the BP Solar and they are more expensive $/W. Are they somehow better, or are all solar panels created equally?

2) If I add 2 more panels (of similar or larger wattage) to my setup, what will that mean for my Xantrex charge controller? Does that mean I need to buy another one of those that will take the extra power? Do I replace the current controller with a larger one, or do I have two smaller ones that will both deliver power to the battery bank? Will they interfere with each other charging?

3) What is the realistic power I will get, in AH, on cloudy/rainy days if I use 4 125 watt BP Solar panels?

4) How does all this compare to simply buying a genset and gas and oil for it?

5) I'm not familiar with installing solar panels. I see both of my panels are wired to each other, then a single pos/neg set of wires runs to the charge controller. If I add more panels, are they just daisy-chained together, like the two panels I have now are? Are there limits to how many you can chain together?

Lastly, I realize I haven't "done the math." I haven't, because the current system *almost* works fine. It's just a tad (25%?) short of keeping up with consumption. I'd like to add that 25%, plus a little more for a margin of error and some luxury like microwaving leftovers.

Have you though about reducing usage?

Fridge/Freezer: We have a number of 2 liter and 2.5 gallon bottles filled with potable tap water. We use them to keep the fridge/freezer full all the time. When we need space, simply take out 1 or more bottles. Definitly cuts down on compressor run time once it is all cold. Plus we have an extra 30 gallons of drinking water if we ever get stuck drifting!

Computer: I don't know what you have, but maybe think about downsizing? My laptop uses very little power. Even our Mac mini isn't too bad. By far the biggest user is the 24" screen. Maybe let the weather dictate your usage? Make do with the laptop screen on overcast days, etc. Also, try to keep printers and other equipment unplugged until needed.

If you need servers running, arrange to run them off-site and remote in. Or set up all your servers on a single laptop with multiple instances of various OS's as required. It'll be a hassle rebooting for sure, but power will be minimal compared to one or big boxes running.

As for power, what about a bigger (or second alternator)? That would probably be the cheapest/easiest way to get extra power for what sounds like a relativly short time period.

Otherwise, I'm sceptacle that more wind/solar would help much on poopy days - they all seem to need a certain level of activity to be useful. It doesn't matter how many times you multiply zero...you still have zero.

Yes, I have thought about reduction in usage. None is possible if I'm to participate in this forum and do other work I need to do online.

Here's a little rundown of why I can't follow the suggestions. Your suggestions may work for some, but they don't fit my particular boating style or work requirements.

I only run a laptop and my internet connection. I'm not sure if you know my history from other forums, but I'm a serious miser when it comes to water and power. ha ha

I run *only* the computer and internet hardware (laptop). I live at anchor, so in order to eat, the freezer and refrigerator are essential while I am spending my time earning money. If I were just doing pure survivalist stuff, I could get by without a refrigerator, but I have a major boat loan to pay off, so I gotta work. This leaves no time for the extra effort involved in shutting down the refrigerator and preserving foods by other methods.

I don't use the alternators (either of them) that I have now. I don't use my engines while I'm at anchor, which will be for the entire summer, close to where you are. Idling diesel engines to create power is an exercise in expense. The replacement cost of the diesel engines (which only have 450 hours on them) would be hard to justify. They are only a couple years old. Plus, you need to buy fuel and oil and all that stuff just to make some power. Add to that the cost of the new alternator and regulator and you've got yourself a very expensive genset.

Currently, I get about 4 or 5 amps out of the panels on cruddy Maine days. Hey, do you guys EVER have nice weather?? ha ha

Ok, so I get 4 or 5 amps on cloudy days. If I double my array, I *should* get 8 to 10 amps on a crappy, foggy day. That's more than my computer uses and keeps my refrigerator happy if I turn off the computer while the refer runs. If I have to run both at the same time, I'd still be using the battery bank, but the quick recharge the next sunny day, or laying off the computer a bit would keep me from getting into a negative AH situation.

So... I gotta make more power somehow.

Either by expanding the solar array or buying a Honda genset for $1000 plus gas, plus oil, plus any breakdowns (not too likely from what I hear). Wind power up here is non-existent for the most part... just comes every once in a while... not a steady wind.

Make sense?

Sean

Just break down and get the Honda. most all the cruisers we know have some kind of generator whether portable or built in. There are just too many cloudy/not enough wind kind of days and if you are going to burn the power having a dependable charge source is a requirement.

Sorry

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Jon D
SV Sirius
Moody 47

Sully it is a tough call in my opinion.
Your solar is marginal on bad days and wind non-existant. So can you add more solar and get what you want? Yes you probably could and you could also do it with a new generator also. If you use your engines you can also generate enough to get you by. So what is the answer? Whatever you want. It's just a matter of where you want to put your money. You can spend another $1500.00 or so and get the solar which you need only occasionally, or you can spend $!000.00 for a genset which you will use occasionally, or you can pay for some fuel and use the alt. you already have on board.
As I understand it the solar can be daisy chained together and that's how it is done on houses. If you get to many for the charge controler then put in a second controler. The genset will provide all you need but will require some maintenince which is a new cost and extra work, plus the fuel and oil for it too. Or you can use the alt. you already have which will cause more maintenance and fuel and oil.
The real gain here is to by more solar since you will always have it at no added cost beyond the original purchase. But too, you will not always need it. It is necessary only on cloudy days.
To me Sully it is a toss up.
Where I used to work the guys would spend $15000.00 for a new more economical car because the gas went up and they didn't like spending the money. But then they had higher ins. and higher Registration to pay, plus the car payments on top of all of it for just a few more miles per gal. It didn't take me long to see for $15000.00 plus the extras I could get many gallons of gas and do tons of repairs and still not have any more expense than they did.
So here it is, to me for just limited use I would run my engines when necessary and boost my batteries that way. So maybe you use a couple of gal. of fuel, what does that cost and how much fuel would you burn over the summer. As I recall you tie to a dock in the winter so you have shore power then.
To me it is all a toss up. If you want more solar get it, but it will be a big expense all at once. If you buy a Genset, again it is a big expense all at once. If you run your engines it is a little expense each time which may be more affordable now and it will take a long time to add up to the solar cost.

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What the hell did I just do

Do the math. How much does it cost per watt for a gen set over say 3 years with fuel and all.

I can't stand the noise from a generator and you need to buy and store dangerous smelly fuel and they things break.

Solar makes no noise, needs no maintenance, but you need a bunch more to get some decent power from them.

When I did my systems I figured on a gallon of diesel per day which is about $3. Some of that use is normal motoring such as using the windlass, entering and leaving a harbor or fuel dock. So the $3 per day is not JUST for energy generation.

Our frig runs off the auxiliary and we make hot water as well a pump out amps. So let's call it $2/day and that's $700 yr for frig, and hot water and general power generation. Our solar helps a bit, but that is affordable for us when we live aboard.

If I had the real estate I would have a solar farm. It's quiet and reliable.

sully
if you get 4-5 amps from your 250 watts on a crummy day how many amp hours a day is that? How close is it to your deficit for the day.
If its close I would double the solar and use the diesels when they get near 50 discharge and just get them back up to about 80%. In this range the batts accept a charge faster so it minimises the run time of the diesel.
When your back in better conditions you will have power to spare. 250 watts is not a lot even in sunny places, thats only about 80 or 90 amphours per day. I am going for 650 watts and another 450 if i can accomodate them.

the connection scheme depends on your panels and controller. if the panels output a higher voltage and your controller can't accept the high with them wired in series then they will be in parralell. The benefits and downsides of series or parralell probably deserves its own thread.

Mike

If I understand you correctly, this is the first time to tend to run a sustained deficit is where you are now. Let me know if I am wrong on this.

It seems if you have enough for this situation, you should definitely have enough for any other. That might encourage you to use more power. Or you will be paying for amps you don’t use. So, it’s for this reason I think you should go with the generator. Hauling it around is going to be a pain unless you intend to secure & shield it on deck. On the plus side, you can be reasonably assured you will get the power on demand without fail.

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Regards,

Maren

The sea is always beautiful, sometimes mysterious and, on occasions, frighteningly powerful.

A very interesting and varied set of replies. Thank you to all.

I am just learning about solar in many ways, so a lot of this reading was helpful. I didn't know if the panels could be daisy chained, now I do - knowing I have to watch out for over voltages on my charge controller. I'm learning.

Also, Whimsical has a good overall idea there that I hadn't even considered. I wasn't considering breaking my idea of how to charge into bulk, absorption and float stages. Genius! This is probably the best way to think about it. It make perfect sense to allow the batteries to drop to 50% on the worst of the worst weeks and use something with more heft to charge them at that level because they will accept a charge faster. This is brilliant! Thanks!

Thinking along those lines, I don't need a Honda at all. All I need is (didn't scallywag say this??) a cheap bulk charger hooked up to my current genset to dump any/all power from it right into the batteries.

My boat is set up as a 12V boat (12v refer, 12v everything), so I have to go with keeping batteries topped off rather than say, an engine driven refer.

Maren, you did interpret the post correctly. I had only run into a little spot of trouble in FL one week where it was very cloudy and hot. Other than that, I haven't had to use the current generator at all. Also, this year we will be going South. We're not wintering over. The wife wants to be warm.

I will give this some more thought... I enjoy keeping my batteries topped off at all times because I don't like buying new batteries. The extra solar would keep them topped off. I'm also with SanderO on not liking the noise of the genset or the gas, oil, used oil, etc... you have to store. We won't be tying up to any more docks for at least a year, since we are going South.

Guess I have to keep noodling this one out...

For myself. Since I do not have any solar at this time I will be getting some when I can afford it. Untill then and after if necessary, I will boost my state of charge with the onboard eng/alt. which makes more sense to me than spending a lot of money on something I do not normally need.

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What the hell did I just do