Solar MPPT or PWM controllers?

Yes it would be. My boat is a 12v setup too, but when I think about pumping in 2kw or more, 12v just can't handle it; I have to go to a higher voltage. I'll just have to amortize the cost over a few years.

The old barge is over 40 years old, well into her second lifetime...
 
I have a 48v panel (235 watts) and a 12v bank (315ah). Per Willie's suggestion I went MPPT. I bought a brand that was recommended by a certain decent company in Ft. Lauderdale that, like me, has found out that brand actually sucks (they don't sell them any more). A 5-year warranty is worthless when you have to buy a second unit to be sure you have one that works at all times. I replaced it with a Morningstar and it's been great. I highly recommend contacting Morningstar, Bill. 48v pushes the specs on this unit but their knowledgeable tech staff said it would work and it's been fine.
 
Willie good suggestion on upping the house bank voltage however everything is 12VDC in my vessel. I'm not going to switch everything out to get improved additional solar charging and capacity.
I do see your point though.
Bill
 
I wouldn't expect you to. This is more of a concept for a new system or complete rebuild. Even with a completely new system, the 12v loads have to be addressed. I'd like to upgrade my system to at least 1k, but that means nearly 100a charging current at 12v, with some really big and expensive wiring, heat, and fire risk. My old controller couldn't handle the amps, so I'd need a another one anyway, and I could use the old controller as the step-down controller. The only really big expense would be the new inverter/charger. I wouldn't use the charger part anyway, so I could probably save money with a straight inverter (if I can find one)

Considering what I spent on my existing system over several years as I cobbled it together, I could probably build a new 1k system for the same amount of money. Prices have come down that much.

Anyway we're getting WAY off topic.
 
Not really. Options are always available at every step.

For example, if I put 2 8Ds in series, and center tap off the one that has the ground, can I run the house at 12V and the inverter at 24 still? I think not because I imagine the battery connected "above" the grounded battery would be over charged regularly due to float voltage maintenance.
 
I'm sure you could, but I think you'd shorten the life of one battery or the other. I think the best way is to have a separate 12v battery and keep it charged from the 24v bank. It probably wouldn't have to be a big battery as it's more of a buffer; with most of the load being carried by the 24v system through the charge control.

If your total PV system isn't over about 700w there's no need as you can stick with 12v. To go more than that though you either have to double up on your controllers or go to a higher voltage. I can't see any way around it. My controller is already maxed out, though I could install a couple more panels on their own, separate controller and wiring.

Then there's the issue of installing a bunch of batteries in parallel.

I've learned the hard way that doing things in pieces gets expensive. I had to replace my controller a few years ago, not because there was anything wrong with it but because it simply wasn't big enough for the additional panels. I sold it and bought a bigger controller; the net cost was less than an add-on. I still had to upgrade the wiring. If I'd planned ahead the first time I wouldn't have had to do it at all. I don't want to make that mistake again.
 
Right now we are fine, because I can tap into the 4/0 cables that run into the bilge. That will keep our DC battery lines good and short provided I can get all the DC solar in place.
 
Same here; I've got 4/0 or maybe 3/0 from the engine room to the distribution panel in the bow, but I still have to run the 10' or so from there to the array. Replacing the wire is a small cost compared to the rest, but there's the labor, and simply finding a place to run them. With a higher voltage I can use the wires that are already installed.

But if I want to go to say 1kw or more I'd have to double up on the controllers, and it starts getting expensive.
 
I have 2 primary house banks one under the salon floor with 3 8D AGMs and another in the bow with 4 31 series AGMs. Both feed and meet in the ER. All primary battery wire is #4/0 marine grade. I have figured out a way to install 5 or 6 200 watt 24vdc panels but it would involve having a hardtop built over the cockpit of the boat.
It's nice to dream.
In that case I would probably treat the 2 battery banks and solar arrays as stand alone systems. Each would have it's own controller. The excess current could be sent to the starting batteries.
Bill
 
Bill 5 or 6 200 watt panels is a lot of real estate. Those things are large and heavy. Six panels is going to be 300 pounds up high and it will require adequate support for rough water.
 
I have the support on my hardtop over the upper helm now for the 3 that are already there, 2 are being upgraded from 130 watt panels to 200 watt units. There are pictures of it in the classifieds section where a guy was looking to have a hardtop custom made and I posted him my aftermarket custom made pipe work and finished hardtop. The additional 2 or 3 will go over new pipe work and a finished top over the cockpit.
like I said perhaps I'm dreaming?
Bill
 
Not sure why you would build a hardtop and then cover it with panels. The panels could BE the hardtop. You'd save money and weight. I think the panels would run cooler, too.
 
quote:
Originally posted by stmbtwle

Not sure why you would build a hardtop and then cover it with panels. The panels could BE the hardtop. You'd save money and weight. I think the panels would run cooler, too.

Click to expand...

I have a few reasons for wanting a rear hardtop some include blocking the sun, wanting to have additional space out of the weather, reduce the sun on the back double glass sliding doors (help keep cooler in the summer) and it would have to look good. I have seen hardtop only tops and they look unfinished to my wife and I. It would be like my larger hardtop over the bridge finished on both sides.
Willie I did say I was day dreaming.....
Bill
 
It might be tough to seal them up adequately. But I have seen it done on a Grand Banks.
 
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