Solar for round-the-world in three years

[TheOnly]

Dear all,
I have been a frequent reader of this forum for quite some time now, and I have to admit it is really awesome. I tried to get by with some local forums in europe, but no way to get the information one is provided with here! Thank you!!

However, even after some weeks of extensive digging (still chewing on HandyBob's Blog « Making off grid RV electrical systems work though), I still have some questions left over for my project-and I hope you can help me.

I have to set up a 47 feet sailboat for a 3 year trip for 2 people (as far as possible without staying in harbours) by myself, and want to install some solar.

The basic (planned) system is now as follows, after some calculating and estimating and extensive reading:
-4-5 230W solar panels mountet on a rack (simple setup, just a bar so you can turn them around it in the back of the boat-never seen this anywhere-why??), set up parallel to avoid shading issues. More specifically: 230wp 7.22 Imp, 18Vmp).
-500AH AGM Batteries, split up in two 250AH set parallel
-the built in engine (Volvo Penta D2-55)
-lead batteries (last owner) of about 300Ah

Where I get stuck is the setup of the charge controllers...at least (who knows what else I forgot-oh yes, a fuse (behind, as they say) the solar-battery circuit).
I figured MPPT might make some sense here. But how?? People say a controller for every panel is best (or maybe every two might suffice). But:

-If I hook up the chargers all seperately to the battery bank, is that the right thing? Or do I have to join them before?
-But then how do I charge the lead batteries and the AGM batteries, with a switch to charge only one type at the time?
-And how do I get the engine to charge if I have to add some juice when in lack of sun? Just join it's outut it in the solar charge controller?

I would really appreciate any help-and promise to contribute back, maybe even opening a project with full documentation once it is done.

Thank you so much in advance,
TheOnly


Ps: Hope I didn't overlook some other awesome post that already explains this all-tried to google, tried to follow every link, but didn't nail it down yet.

[Stumble]

I am only moderately familure with solar panels so I will let the experts chime in on that. But there are two things that struck me.

1) the old batteries are going to be at least three years old plus their existing age. This is the point at which batteries become prone to issues, so I would probably plan on tossing them right before leaving, and replacing them with matching AGM's.

2) there are a lot of good reasons to have a seperate starting battery for the engine, but almost no good reasons for having multiple house banks. Ideally I would only have two banks onboard. A starting and a house set. Since the larger the bank is the lower the discharge percentage.

I would also install a permanent jumper cable system like I have on my fishing boat to allow me to start the engine from any bank on board if the starting battery dies for some reason.

[Chasing Summer]

I've purchased the solar panels for my Spencer 42. I'm going quite simple. I'll carry an alternator but won't even have it installed on the engine. I don't plan on running the engine for charging.

I would discourage you from hanging them off the stern especially on a flimsey able-to-rotate setup. What happens in a strong following sea when, and you will, take a wave over the stern?

--If I hook up the chargers all seperately to the battery bank, is that the right thing? Or do I have to join them before?
The solar array has one charge controler that handles all the charging amps. Carry a spare or two.

--But then how do I charge the lead batteries and the AGM batteries, with a switch to charge only one type at the time?
I would only have one type of battery and all of the same age and amp rating.

--And how do I get the engine to charge if I have to add some juice when in lack of sun? Just join it's outut it in the solar charge controller?
Correct, the solar charge controler will see a high than battery voltage and shut down the controler.

Check out these guy's web page: Aurinco solar start page
You mention Europe so I presume you're there. The USA team goes to all the boat shows. They're very knowedgable and friendly. Call them on the phone. They helped me with my system.

If you scroll down on my blog you can see how I have my panels on my cabin top.

[Nicholson58]

Why in the world would you not plan to be able to charge from an alternator? Always plan for multiple back-ups 'cause **** happens. I put Balmer alternator multistage battery charger/regulator on the engine so the alternator performs as a multi-stage charge controller. This, I consider a must have. There is also one on my generator so that the generator alt can charge.

There are charge controllers that can manage multiple inputs from wind/solar/gen/alt. There can also manage multiple battery banks.

Read over Bob's stuff again. there is a lot of advice regarding charge management. You will need really good battery monitors as Bob notes. Personally, I am nervous about overly complex systems and would be tempted to use selector switches to control where & what is being charged. You will gain benefit from MPPT if the open circuit voltage of your panels is substantially above your battery voltage. Panels should most often be wired parallel to minimize shade losses. Good panels today are about 20% efficient or maybe more. You can get a lot of cut-rate panels that yield 12 to 15 % efficiency but your space is premium.

[Chasing Summer]

Nicholson58 ... I lived over 2 years in my 33 ft motorhome dry camping and only used my generator one day. That was during June Glume in San Diego. I had almost 200 watts and all the electrical loads of a modern motorhome. The only thing my inverter wouldn't run well were the hair dryer and microwave. My boat has far less electric load than my motorhome. Besides, I plan on having a belt driven sea water pump mounted where the alternator mounts. Like I said, I can always change it out and charge from the alternator / engine.

I agree with you ... read, no study Bob's stuff again. There is a design for every application. There are charge controlers for every setup conceivable.

[Horror Hotel]

It's silly to have the engine run for even 10 minutes and not have a alternator spinning. If only to replenish the starter load that was used. Getting rid of something already in place and functioning, but still carrying it around is beyond weird. It flat out makes no sense. I doubt you will find anyone here ever to agree that it's any sort of reasonable plan. Please heavily rethink this. Just stating it as a plan makes me think you cruising plans are based out of speculation rather than reality. This comes from a guy with freezer full of steaks and 5 solar panels.

[Chasing Summer]

Well, see, there you go ... I have no steaks, no freezer, not even a fridge. I'd rather have a bronze pump turning in it's place than to start up my engine only to find out the rubber saltwater impeller has given up the ghost and my engine overheats while I'm trying to run against the tide to an anchorage. Just my personal preference ... which is subject to change at any time in the future.

[Horror Hotel]

It really isn't better with warm water and dried foods, it's not the 60's anymore. Have huge solar is great, just don't shoot yourself in the foot to be off the grid. I'm very off the grid.

[roetter]

4-5 times 230W is 920 to 1150W at perfect conditions.

That would mean full sun at freezing temperatures. When the panels get hot they loose efficiency. So you will be around 950W max. At 14V that would be 67A peak. An Outback Flexmax 80 will handle that easily. It is fully programmable and gives you statistics for the 120 days. So just one MPPT charger for the lot.

From the panels to the charger you need a fuse rated at a little, over the max A the panels produce combined. See here for size of fuse.
http://www.bluesea.com/resources/1441

From the charger to the battery use another fuse.

You can use fuses like this one

http://www.bluesea.com/products/cate...uses/ANL_Fuses

Other recommendations:
-Combine both house banks into one. Gives you better live
-Keep the alternator.
-make sure you can secure the panels for stormy days. That may be as simple as running lines from the corners down so they can not rotate.
- inspect all cables on a regular basis. Touch them at their ends. I use an automotive infrared temperature gun. I have seen many bad connections with cables getting so hot that they melted, close to causing a catastrophic fire. Just had one brand new one on my boat (only hot to boiling water) and on a friends boat with a fuse holder melted to disconnect and another cable so hot I burnt my fingers.

[TheOnly]

Thank you for all that information! Much more than I expected-really great! Sorry for the late reaction, but I was sleeping over in Europe (as ChasingSummer guessed).
As you probably noticed from the Imp value, I screwed something up-it had to be 130W, not 230. And I even read it over four times....
I will just reply to one at a time:
@Stumble:
I agree with you concerning the two house banks-but the lead batteries are already in there, so I think I will just use them up until they are all gone. They are still in pretty good shape, so why waste them? I will adhere to your advice concerning jumpers, good idea that!
@Chasing Summer: Thank you in particular for answering step by step to all my questions. The alternator is already built in-I just guess it could be a good idea to have a way out if - for example during the atlantic crossing - there is a problem with the solar panels (whashed away, e.g. ).
Then instead of having to take over from the autopilote 24/24 with just two people on the boat, I would prefer to bea able to charge for the night by engine. And as I said, it is already there, so... And it would still be nice to be able to use the watermaker. (I think that answer should make Nicholson58 hapy too-lots of stakes with me!!).
@roetter: Combining the two house-banks would be nice, but combine lead and AGM - i think to remember - is considered not a good idea. As I just want to use up the leads (they are from last year), I would think that is not a way to go for me. But thanks for the link, and the hint concerning cables - I will look out for that.

[TheOnly]

I will just nag you once more concerning the problem with hooking up the alternator (I did get one answer, but I think I have to misunderstand it).

-Do I really just plug the alternator into the solar controller (say the flexmax suggested by roetter) as Chasing Summer suggests? I don't quite get this-he says the solar cotroller will then shut of-but then the alternator wont charge, so WHY? I have a feeling he meant to say I should just hook up the alternator to the battery-bank... But maybe I would even like the solar and engine to charge at same time-for example motoring on a sunny day. What then? I'll go and try to find something at Bob's....

-Concerning the two different charge controller: Many say this is better because the panels are independent this way. You all disagree?

I think it all comes down to the question: What happens if two much Amp arrives at the battery? (Say, two MPPT's charging and motor running)? The batteries wouldn't be able to take it all, so where does it go? Blow up, disappear?

Thank you once again!!!

[roetter]

Originally Posted by TheOnly

I will just nag you once more concerning the problem with hooking up the alternator (I did get one answer, but I think I have to misunderstand it).

-Do I really just plug the alternator into the solar controller (say the flexmax suggested by roetter) as Chasing Summer suggests? I don't quite get this-he says the solar cotroller will then shut of-but then the alternator wont charge, so WHY? I have a feeling he meant to say I should just hook up the alternator to the battery-bank... But maybe I would even like the solar and engine to charge at same time-for example motoring on a sunny day. What then? I'll go and try to find something at Bob's....


-Concerning the two different charge controller: Many say this is better because the panels are independent this way. You all disagree?

I think it all comes down to the question: What happens if two much Amp arrives at the battery? (Say, two MPPT's charging and motor running)? The batteries wouldn't be able to take it all, so where does it go? Blow up, disappear?

Thank you once again!!!

Misunderstanding. The alternator, the solar controller and anything else that might charge go to the battery directly. All will charge at the same time if they can produce energy.

No blow up or magic disappearing.
Lead acid batteries are self limiting in their acceptance rate, and since the charge controller are all voltage limited nothing bad will happen. You can put a 1000A charger on it. All that will happen is that the battery will immediately reach the absorb voltage (usually 14.6V). At that point the charger(s) will throttle the amps down to maintain this voltage as the batteries get filled.

[noelex 77]

1000w of solar should mean you have loads of energy.

One good quality controller like the outback fleximax is probably the best option. Multiple MPPT controllers offer the promise of slightly better output, but the potential gains small when the self consumption is factored in. However, for redundancy and slightly better effeciency two outback 60 are a possibility

Two house battery banks are an asset on crusing boat. You can combine different types of batteries, or different ages of batteries without any problems. Most of the time the banks can be parrelleled.

For a bit of extra wiring and a an additional battery switch you gain a lot of versatility.

If nothing else when embarking on long voyage to remote places you can keep the best batteries from your old bank and add a couple of new ones in a separate house bank. This is cheaper than throwing away all your batteries that still have usable life and having batteries of different ages means that all batteries are unlikely to fail together.

[leftbrainstuff]

Evolution of current best practice is the key to success. We have wind, solar, generator and engine charging. Having options, a robust collection of proven marine grade technologies works for us. We live and run a startup and a consulting business from our boat.

[noelex 77]

Originally Posted by TheOnly

I think it all comes down to the question: What happens if two much Amp arrives at the battery? (Say, two MPPT's charging and motor running)? The batteries wouldn't be able to take it all, so where does it go? Blow up, disappear?

Multiple charge sources (more than one solar controller. Solar an alternator, solar and wind etc) are not generally a problem. Each source will regulate.
The solar controllers gereally regulate by turning off the solar panels briefly. No power is produced when the solar panels are disconected. You can leave a disconected solar panel in full sun. They will only produce power when a circuit is formed.