Where To Put Solar Panels?

[RaymondR]

I started with 2 x 80 watt panels and 1 x 120 amp hour house battery and then went cruising. I now have 500 watts of panels and 1000 amp hours of batteries. There are a number of things I have noticed about panels:

You never seem to have enough of them.

They definitely do deteriorate with time.

They do break fairly easily so do you go for the expensive ones and hope you never break them or the cheaper ones so that they are less expensive to replace if you do.

You cannot buy the same size panels as the manufacturers change models and sizes all the time.

The last item is important if you don't want to have to rebuild the support structure every time you change or increase the size of your installation. My first support was made from SS tube and had to be thrown away when I expanded the wattage of the installation. It's replacement is alloy, which does not look anywhere as nice as the SS but since it is bolted together and alloy is both easy to work with and inexpensive I am able to very readily make changes to it if required.

You will be amazed at the amount of stuff - antennas, cockpit HiFi speakers, wind generator masts, junction boxes, anchor, stern and port and starboard lights etc - that a solar panel support structure will attract once you have one.

[D&D]

Originally Posted by RaymondR

There are a number of things I have noticed about panels:

You never seem to have enough of them.

Agreed!

Originally Posted by RaymondR

They definitely do deteriorate with time.

Perhaps, but newer cells are proving remarkably more long lasting. At the risk of ...and again admitting our bias toward SunPower, it needs to be said in this context that SunPower's 25yr warranty is also the best panel warranty in the market, reflecting unmatched confidence in their panels. While the SunPower warranty excludes use in salt water, cruisers can still be comforted by;

• SunPower panels powered the global circumnavigation (on solar power only) by Turanor Planetsolar Sep 2010-May 2012 with no signs of corrosion, nor any efficiency loss whatsoever...and Planetsolar continues to cruise today as an ambassador for efficient marine solar power
• SunPower panels perform brilliantly on our CatNirvana...with many (!) instances of contact with salt water; and
• SunPower assure us that, for panels installed on vessels, any problems with a SunPower panel -- So far, we have seen none -- will be backed with the full SunPower warranty unless the problem is fully attributable to salt water exposure.

Originally Posted by RaymondR

They do break fairly easily so do you go for the expensive ones and hope you never break them or the cheaper ones so that they are less expensive to replace if you do.

You cannot buy the same size panels as the manufacturers change models and sizes all the time.

A good point, although it strengthens the argument for buying the best available panels in the first instance.

[Mariner62]

Originally Posted by GILow

Are they the Mitsubishi mono crystalline type?

They are Suntech STP225 - 20/Wd.
Polycrystalline.

[Mariner62]

Since this thread seems to be all-encompassing - here's another question for the experts :-)

I have two panels side by side over the bimini. Sometimes one panel is shaded, by the sails for example, and the other is in full sun.
I have a MPPT controller which can handle panel voltage up to 150V.

Would I be better to wire them in parallel or series, and should I install external blocking or bypass diodes?

Seems to me that parallel wiring would incur four times the cable loss of series wiring, so would need much more copper in the wiring to get the losses back to something acceptable. So series connection is best from this perspective?

But what about partial shading effects - series connection means a shaded panel severly limits the output of the unshaded panel. Can this be solved by installing external bypass diodes?

I can understand how bypass diodes work on an internal cellular level, as the cell voltages are similar to the diode drops, but its not so clear to me how this works at the panel level when the fully insolated panel produces 28V.

Or ... Have I taken this too far ???

[GILow]

Originally Posted by D&D

We believe you might indeed be wrong. .

Yep, you are right, I am wrong. I just looked into it a bit more and was surprised to see figures ranging between 16% and 21% efficiency between poly and mono crystalline.

Geez, this stuff changes SO fast! Hard to keep up. Suddenly my very efficient Kaneka's on the house are looking very old fashioned! (Though thankfully the area on the roof is not needed for anything else and I still believe they have a good reputation for long life near the sea, and we are only 150 meters from the beach, so that is important.)

I will have to do a lot of research before I replace anything on our boat, but thankfully that is a way down the road yet.

[GILow]

Originally Posted by RaymondR

They do break fairly easily so do you go for the expensive ones and hope you never break them or the cheaper ones so that they are less expensive to replace if you do.

This is my concern about all the eggs in just two baskets. Although it is neater to put up two big panels, I wonder if it might be safer to put up four smaller panels if mounting space is not an issue.

Ah, so much to think about... Must stay focussed on more mundane things like skin fittings this Friday. Focus... focus..... .... ..... hmm... solar... hmm..

[foolishsailor]

I am curious about the SunPower panels and their ability to deal with partial shading?

[mbianka]

My life on board is working out quite nicely thank you with just two old 75 watt 12 volt Siemens panels for my house bank and two 48 volt Kanaka panels for my electric propulsion bank. They have been incorporated into a solar bimini :
THE BIANKA LOG BLOG: SOLAR BIMINI PROJECT CONTINUED
Yes, there are some shadows from the boom but, that does not stop me from running an Engel cooler in freezer mode 24/7. Using the the panels as cover over the cockpit also means no repairs or replacement of Sunbrella fabric ever. The dodger has also stood up to the winds of Superstorm Sandy. If I was more anal I could move the boom off to one side or another but, since the system meets my needs as is I just open up a beer and relax in the cockpit.

[Mariner62]

Originally Posted by GILow

This is my concern about all the eggs in just two baskets. Although it is neater to put up two big panels, I wonder if it might be safer to put up four smaller panels if mounting space is not an issue.

Yeah, that was something I thought about. But these panels are standard 'house' panels, a couple of hundred bucks each, and the mounting structure, which is designed to handle different panel sizes with minimal hassle, cost 4 times the cost of the panels. The controller and wiring infrastructure cost more than the panels, so the panels are not the big ticket.

The other thing about more panels, is the weight gain. I have two panels, less than 40kg. I struggled to find a 3 or 4 panel solution which was less weight. (Without going to flexibles, which blew the budget entirely).

The other advantage of the cheaper 'house' style panels is that they tend to be higher cell count than marine panels, therefore operate at higher voltage and lower current. Makes the wiring easier and cheaper.

Now, get back to those skin fittings :-)

[The Garbone]

Originally Posted by o_q

Hey, don't you work for these guys?


Are you well acquainted with marine solar panel installations? If so, given your knowledge of your brand, what do you suppose I can reasonably put on a Catalina 27?

On our C27 we have one of those low cost 15watt panels and charge controllers bought on Amazon. Being weekend sailors it is more than powerfull enough to keep my 300ah (2 deep cycle cells) of batteries sitting above 13.5v. Attached it to the stern pulpit with Magma grill brackets.

For weekend use we would be hard pressed to drain our batteries. When out for a week or more we usually stop a night in a Marina every few days to get a shower not from a bag and top off our batteries and water. We could probably get by without the top off batteries.

Usually we run a handheld VHF when moving, turning on our depth sounder and real vhf only when needed. We use an O2 cool fan at night, designed for tents it is 10", moves a lot of air and burns less than .85amps, and of course our anchor light. We also keep our phones, Ipod, kindles charged.

If our outboard were hooked up to charge things would be even better.

In the next few years we plan on spending a month in the Keys and another in the Bahamas. If we do that I may go up to 40watt and a better grade of controller.

[familycruisers]

Guess that does pose a question, what are you trying power?
We are living aboard, have refrigeration, laptops, Long range wifi, tv, bluray, tablet, three phones. I pull the freezer down during the day, and let it come up some at night. Puts less strain on the battery, and stol keeps everything frozen.
510watts gives me plenty to spare, and as others have said, the panels were the cheap part. I paid .85 per watt.

[bratzcpa]

We have a 1973 Catalina 27'. I mounted two full size panels off the stern rail. They had to be offset to the side (starboard) a bit because of the outboard motor mount in the middle.

These are older panels (probably NOT super efficient), but they worked great for us. We were on a two month cruise in the Bahamas and NEVER hooked up to shore power. We alternated the charging between two different batteries day to day. In other words, on Monday, we would be charging Batt 1, and use Batt2 (lights, gps, VHF, radio, computer, etc,). Then on Tuesday, we'd switch and charge Batt 2, and use Batt 1 for the load. Two simple Perko selectors allowed us to easily swap back and forth.

During the entire two month trip, we had one 5 day dark/rainy/dreary period where we got things pretty low on both batteries. But other than that, it worked great.

We also used a small Morningstar controller.

If you want pictures of the install and/or components, just let me know.

~markb

[o_q]

Originally Posted by bratzcpa

We have a 1973 Catalina 27'. I mounted two full size panels off the stern rail. They had to be offset to the side (starboard) a bit because of the outboard motor mount in the middle.

These are older panels (probably NOT super efficient), but they worked great for us. We were on a two month cruise in the Bahamas and NEVER hooked up to shore power. We alternated the charging between two different batteries day to day. In other words, on Monday, we would be charging Batt 1, and use Batt2 (lights, gps, VHF, radio, computer, etc,). Then on Tuesday, we'd switch and charge Batt 2, and use Batt 1 for the load. Two simple Perko selectors allowed us to easily swap back and forth.

During the entire two month trip, we had one 5 day dark/rainy/dreary period where we got things pretty low on both batteries. But other than that, it worked great.

We also used a small Morningstar controller.

If you want pictures of the install and/or components, just let me know.

~markb

How many watts?

[o_q]

Originally Posted by familycruisers

Guess that does pose a question, what are you trying power?
We are living aboard, have refrigeration, laptops, Long range wifi, tv, bluray, tablet, three phones. I pull the freezer down during the day, and let it come up some at night. Puts less strain on the battery, and stol keeps everything frozen.
510watts gives me plenty to spare, and as others have said, the panels were the cheap part. I paid .85 per watt.

I figure I'd want to power a laptop, a fridge, and up to 150 watts of stereo (probably mostly at medium-low volume). But I don't own a boat, so I don't know what else I'd need besides lighting and VHF.

[jared1048]

as discussed on a different thread is getting sunpower panels. Local distributor's in my area won't sell them to me( marine install) and even if they did they were something like $1200 and you need to use their specific controller. So yeah. If you got the $$$$

I'll stick to the tried n true Kyocera