Shore Power vs. Solar Panel Help me Decide!

[mike]

As mentioned in a previous post, we're moving to a new marina in about a month. I'm trying to decide whether or not to pony up the extra $20/month for AC, or buy a 32 watt flexible solar panel setup for around $300.

In favor of the solar panel, I like the fact that the chances of the boat bursting into flames due to a faulty battery charger are pretty much nil, plus the power cord would be one less thing to have to do when taking the boat out. Also, the panel would supply a little bit of power when on trips. After about a year and a half, I'd be even in terms of money.

On the other hand, it's probably safe to say that my Xantrex TrueCharge 20 will do a better job at keeping the batteries in good shape. And, I like to run one of those West Marine "Turbo Dryer" things in the cabin, plus I have a small clip-on fan that helps circulate air through the aft berth when the boat is at the dock.

All of my tools (except the Dremel) are battery-powered, so, for the most part, working on the boat wouldn't be a big problem (and if I HAD to briefly use AC to get something done, I guess I could either bring my generator, or mooch off of a nearby slip).

I welcome any advice... yeah, I know, it's not THAT big of a decision, but I'm frozen.

--Mike

[baldbaby2000]

We use both options depending on where we're at. At our normal slip at Lake Granby in the summer we just use the solar panel and charge with the motor if needed. We also go to Pueblo Res. at times in the winter and need shore power to run our heater. When we're sailing we usually have our solar panel on the deck so it's even charging then.

[mike]

If the decision is either/or, I'd go with the AC power in a heartbeat. No question in my mind. It may take longer to break even if the panel is stolen and below your deductable.

Hmmm... hadn't really considered that, but that's a good point.

--Mike

[Frank C]

Two other factors to consider ....

• 1. how much time are you spending at the slip? It can be really convenient to have that AC for a weekend working party ... or just a party w/ friends or fam.
  
  2. How large is your outboard's charging capacity, and how much time do you run it? In my case, I use the Suzi 60 at least a half-hour per sailing day for running the 3 channel-miles to and from the marina.

That alone (3500 rpms on a 21-amp alternator) is ample to support my batteries. I can imagine that smaller alternators would need lots more run-time to recharge weekend battery drain.

[Chip Hindes]

Do a realistic survey of your DC electrical usage. Do a second survey or how often and at what speeds you run the motor, and how much you can expect to recharge through the motor alternator. The solar panel will have to make up the difference.

According to the West Marine advisor, you can expect about 7.5 amp hours per sunny day from a randomly oriented 30-watt solar panel. That's not very much, compared to a day's worth of electrical usage for most boaters, and it's equivalent to running the motor for less than an hour (per day).

Flexible or not, I don't believe a solar panel is something you would want to step on, and a 30-watt panel is, what, about 2x3 feet? That's a large chunk of fairly valuable real estate on the deck of our boat.

In your area, can you get away without running one of those driers all the time? My boat will mildew in less than a week if I don't, and there's no way you could power one of those off a small solar panel. So I'd pay the $20 per month for that reason alone. If I didn't need it, I'd skip the electrical hookup, skip the panel, and run my motor for a bit each time I use the boat to keep the batteries topped up.

[Moe]

I've never seen that West Advisor article, but their projected 25% of wattage in amp-hours/day is what most RVers get with horizontally mounted panels, at the summer solstice. In spring and fall, it's about 2/3 of that.

The amorphous silicon panels like the flexible Uni-Solars, while more shade tolerant, are less efficient, and thus larger than mono or polycrystaline panels. Their 32 watt is about 16-3/4" x 56-1/4".

Finally, they may be being discontinued. Northern Arizona Wind & Sun says,

Although not confirmed by the manufacturer, it appears that all Unisolar panels under 64 watts are being discontinued, including the flex modules. So far we have been unable to get a straight answer from Unisolar as to what will be available.

If this is the case, I'd be concerned about getting replacement under warranty.

--
Moe

[Catigale]

My MIldew problem in upstate NY as been 99% solved by the addition of two Nicro vents which push lots of air into her.

Your mileage in Louisiana may Vary, Mike.

[Tony D-26X_SusieQ]

I have a 2 battery system on my boat and have never had to use an external charger to keep them fully charged. I have gone the entire winter with the batteries hooked up on the boat and still have had plenty of cranking power for that first start of the season so you may be able to get by without either option. I just power up the engin and let it run for about 30 minutes on both batteries before returning to the marina and have no problems. I admit that I don't put a very heavy load on the batteries as a rule.

[Chip Hindes]

Well, OK, I'm sure they work fine, but aren't two Nicro vents a $100-200 additional expense compared to the AC heater/circulator? You also have to cut additional holes through the topsides and consume additional valuable topsides real estate. And watch your step.

In my case, the shore power's already there for free (though I'm sure I'm paying for it indirectly). Whether I use it or not is up to me, so I use it.

[mike]

Two other factors to consider ....

• 1. how much time are you spending at the slip? It can be really convenient to have that AC for a weekend working party ... or just a party w/ friends or fam.

Aside from me working on the boat every now and then, we don't spend any time at the slip.

Do a realistic survey of your DC electrical usage. Do a second survey or how often and at what speeds you run the motor, and how much you can expect to recharge through the motor alternator. The solar panel will have to make up the difference.

I've thought about that quite a bit, and I don't think the panel would have a problem making up the difference. We'll probably be running the motor for only a half hour or so on the way back in on weekend trips, but there will be at least a few weeks between trips, which I'd imagine would be plenty of time to get the batteries charged back up.

Flexible or not, I don't believe a solar panel is something you would want to step on, and a 30-watt panel is, what, about 2x3 feet? That's a large chunk of fairly valuable real estate on the deck of our boat.

Actually, the spot I had picked out for it was on top of the bimini. If I were to position it at the aft end of the bimini, it wouldn't be directly shaded by the boom (though I'd need to confirm which direction the slip faces).

In your area, can you get away without running one of those driers all the time?

Hmmm.... probably not. I do have one Nicro solar vent installed in the front hatch, but I found that, although it helped, it didn't totally solve the problem for me.

I have a 2 battery system on my boat and have never had to use an external charger to keep them fully charged. I have gone the entire winter with the batteries hooked up on the boat and still have had plenty of cranking power for that first start of the season so you may be able to get by without either option. I just power up the engin and let it run for about 30 minutes on both batteries before returning to the marina and have no problems. I admit that I don't put a very heavy load on the batteries as a rule.

That wouldn't work for us, especially being so close to our cruising grounds now. The amount of power we draw from the batteries would not be put back by just a half hour or so of motoring.




Thanks for all the comments. At this point, I'm leaning towards shore power.

--Mike

[Chip Hindes]

We have the smaller bimini. It's useful as a sunshade, but that's about it. We never leave it up when the boat's not in use, and we fold it down and out of the way whenever we dock, swim, or otherwise need to move around in the cockpit; even when we're doing serious sailing. Having to leave it up permanently to support a solar panel wouldn't work for me.

I believe the flimsy aluminum frame would be problematical in a stiff wind, let alone trying to support something as heavy as a solar panel, and (at least if it were the one I have) I would be concerned about losing both the bimini and the solar panel. Even if your bimini's a lot better than mine, you certainly wouldn't attempt to trailer with it up, and a solar panel mounted, would you?

[mike]

I believe the flimsy aluminum frame would be problematical in a stiff wind, let alone trying to support something as heavy as a solar panel, and (at least if it were the one I have) I would be concerned about losing both the bimini and the solar panel. Even if your bimini's a lot better than mine, you certainly wouldn't attempt to trailer with it up, and a solar panel mounted, would you?

Our is plenty big enough, and seems sturdy enough to handle a flexible solar panel. I've only trailered the boat once, and I lowered and secured the bimini beforehand.

--Mike

[Moe]

I see Chip already covered one of my concerns, and that's the lightweight MacGregor bimini. I don't think I'd leave it up with the boat unattended, even without a panel on it. Even the heavy-duty stainless one on our Whaler is only rated for 45 mph, and storm winds can often exceed that.
--
Moe

[mike]

I moved the boat to her new home this weekend... the new slip is oriented east-west. I'm guessing this would reduce the effectiveness of my solar panel on the bimini plan, since the panel would be partially shaded by the mast/boom for half the day.

On top of that, as Moe alluded to, something is indeed up with Unisolar... their flexible panels are in extremely short supply (no one seems to have the 32 watt panel). While no one has told me they are no longer being manufactured, several dealers told me they don't expect a resupply until next year.

But hypothetically speaking, does the east-west direction of my slip render this solar vs. shore power decision moot?

--Mike

[baldbaby2000]

That's too bad if the Unisolar flexible panels are being discontinued. I've used them for years without a failure. They have been stepped on without noticable damge but I try to avoid it. I put a bungee cord in each corner and I'm able to move them around depending on where the sun is. I usually just have it on the hatch under the boom. Between weekends seems to be fine for a recharge.