If you see me at a trade show and notice that the company shirt I’m wearing does not fit too well around the collar, it is probably because it was bought at low cost from an outlet store by the embroiderer. The label suggests that this shirt is from a highly respected manufacturer and is of high quality, which is all true up to a point, but somehow the buttons and button-holes were mis-aligned during assembly, and so this item was sold off as a “second” or reject item in the manufacturer's outlet store.

Well, guess what? Somewhere out there is an outlet store for low grade, off-spec, SunPower® solar cells.

During manufacture, after solar cells have been tested electrically they are sorted into different “Bins” dependent on how they performed. Some will be over achievers and be put aside for research purposes, while others will simply fail miserably and be destroyed. Those remaining are the Good, the Bad, and the Ugly cells; Good being “Prime”, Bad being “Off-Spec”, while the Ugly cells will have visual or cosmetic defects.

The Prime cells are further graded into High, Premium, and Ultra performance categories, while the Off-Spec cells are

I've just come across yet another sailing magazine article giving inaccurate and misleading information on solar power for boats. (Why don't they bother to do some research and ask the real experts?) So here is a list of ten myths and busts in an effort to set the record straight.

MYTH 1 - Glass solar panels with aluminum frames are the most efficient

BUST - No, no, no! The type of cell determines how efficient a solar panel is, not how it is constructed. Coastal offers three types of panels all made with the highest available efficiency SunPower® cells:

1) aluminum-framed glass panels,
2) razor -thin walk-on panels, and
3) flexible panels for installation in canvas areas like biminis.

All three types enjoy the same high efficiency because they all use the same cells with 22.5% efficiency. Glass panels are more common and less expensive, but not necessarily more efficient.

MYTH 2 - You can't walk on solar panels.

The US Federal Government continues to offer a solar energy tax credit, applicable to your primary and second homes, i.e. your boat or RV! As long as there is a head and galley onboard and it is docked in the United States, your vessel or vehicle qualifies.

This federal tax credit, in place since 2005 (known as the Investment Tax Credit, ITC) has been extended yet again to its current expiration through 2034 for non-commercial installations. Best grab it while you still can!

While the claim may be that this type of panel has superior shade resistance, the results can be very different.

FACT: The smaller the cell size, the less shading it requires to be 100% shaded. The same amount of shade that completely covers a small cell might only cover ¼ of a larger cell. Larger cells are better for shade resistance.


FACT: If just one cell is 100% hard shaded, the output from that series string of cells will be zero, or close to zero.

FACT: Silicon solar cells consume power as well as produce power. If a cell is shaded, it will consume power from the other cells in the series string, resulting in diminished output and heating up of the shaded cell.


FACT: If several series strings of cells are connected in parallel without the installation of blocking diodes, the power from good strings will feed into a shaded string resulting in diminished panel output and the chance of cells burning.


FACT: Blocking diodes prevent back-feeding in parallel circuits, but reduce voltage output by 0.7v.


FACT: By-Pass diodes prevent cell burning ("Hot-spots") and do not consume any power or diminish panel output.

FACT: The more cells and electrical connections there are on a panel, the more output-reducing series and shunt resistance the panel will exhibit, and the more chance of a connection failure, particularly if the panel is flexed.

For best results, look for a panel with large, high efficiency cells, in one series string, with by-pass diodes protecting any string of 50w or greater.

Blocking diodes must be installed on circuits or panels connected in parallel.

Which type of Solar Panel is best for Marine Installations?

Monocrystalline; Polycrystalline; SunPower®

3 - 4 - 5 Remember these numbers. These are the factors by which you need to divide the rated wattage of a panel to give an estimate of the amp/hr daily yield, at 12v, that a panel might produce dependent on the type of cell.

• • For a panel with SunPower® cells, divide the watt rating by 3.
  • For a panel with regular monocrystalline silicon cells, divide the watt rating by 4.
  • For panels with polycrystalline cells, divide the watt rating by 5.

Example: If we have one of each type of panel, all rated at 100 watts, then the one with SunPower® cells will produce somewhere in the region of 33 amp/hrs per day; the one with regular mono cells will produce around 25 amp/hrs a day; and the panel with poly cells will produce 20 amp/hrs or so a day. (Note: This is assuming a good solar day, using a MPPT controller, and with a full time load). So why the difference?

The Green Energy Revolution is well underway, with or without the assistance of subsidies offered by various world governments. Based on what we hear at recent boat shows, the drive for putting solar and wind power on boats is more and more a must-have. People are moving beyond simply installing LED lights and upgrading to energy-saving 12/24v refrigeration.

They are looking at maximizing the limited real estate on their boat with solar panels, whether those panels be home-style, heavy, glass panels, or the light weight, marine-grade, flexible panels that can fit on canvas or a hard top. Add a wind generator or hydro generator and your charging regime has just massively expanded beyond what your alternator or dock side battery charger can do.

Here at Coastal Climate Control, we talk to a lot of boat owners, at shows and in the course of daily business, and in general most of the people we talk to who have wind generators seem to be less than ecstatic about their performance.

We commonly hear gripes that what these device's specifications promise on paper seldom seem to materialize in real life application. And then the cost, complexity, and effort of installing wind generators apparently put a lot of people off, not to mention the unease of having sharp-edged blades whirling away within a daggers-throw of one's head!

Some wind generator owners report that their systems perform well on passage, when the boat is beating into the wind, although it is well known that gentlemen never go to windward ... but then when the destination is reached and the hook dropped in the sheltered anchorage of an island, the wind generator seems rarely to have the oomph needed to fully charge the battery, at a time when reliable charging is most needed.

So, have wind generators had their day?

Solar Tariffs - Feel the Pain?

When it comes to tariffs, you’ll have to go a long way to find anything to beat the 249% tariff we were recently charged on a couple of small, specialized marine solar panels imported from Solara in Germany. These smaller panels are not as popular here in North America as they are in Europe and around the Med, but we were selling one or two along the way, and needed to replace stock. It transpired that the cells in these panels were manufactured in China by a company that is not on the list of preferred solar manufacturers, and so we got walloped with the huge tariff.

There's a lot of talk of trade and trade agreements in the run-up to the election, but I've heard nothing of how the substantial anti-dumping and anti-competition tariffs applied to Asian solar products are protecting US interests.

Originally applied to just solar cells, these tariffs were expanded last year to also include complete solar panels made in China and Taiwan, and add a whopping 250% or so of duty to the imported price of all but a very few manufacturers of Chinese and Taiwanese panels.

The results of these tariffs are already being seen in the semi-flexible panels, popular in marine applications. Many of these low-cost panels suddenly shot up in price, and several outlets stopped offering them altogether, but the tariffs are not the only reason .....

Are you confused about the wording on some solar panel guarantees and/or warranties? Well, you're not alone, but first let's define what is a guarantee and what is a warranty.

Guarantee: A formal promise or assurance (typically in writing) that certain conditions will be fulfilled, especially that a product will be repaired or replaced if not of a specified quality and durability.

Warranty: A written guarantee, issued to the purchaser of an article by its manufacturer, promising to repair or replace it if necessary within a specified period of time.

So a guarantee looks to be more like a loose promise, whereas a warranty is in written form and contains a guarantee with certain time limits. In this discussion we'll assume we're working with written warranties, whether packaged in with the product, or more likely these days, posted somewhere on a manufacturers' web site.

Other than the strange and fruity wardrobe, Robin Hood and his Merry Men had a noble agenda in England back the middle ages, i.e. rob the rich and give to the poor. They probably kept a little back for themselves for expenses, i.e. something to make the men merry plus some bling for Maid Marion, but overall they fought a worthy fight for social justice and equality. Fast forward a few centuries to 2018.

Our modern-day Robin Hood wannabe comes in the form of Robert Lighthizer, the US Trade Representative (USTR), who recently announced that tariffs will be imposed on virtually all silicon-based foreign-made solar cells and panels entering the US effective February 7, 2018. This is a four-year program that starts this year with a 30% tariff, and which then decreases by 5% each year ending up at 15% in year four.

Now, unlike the anti-dumping and unfair subsidy tariffs that have been in place since 2012, these new tariffs are not aimed exclusively at one or more countries of manufacture. Those tariffs originally singled out China, but the Chinese manufacturers then started country-hopping and ended up producing solar panels in other countries to avoid the stinging tariffs when imported into the US.

Not to be caught out, Mr. Lighthizer has taken a different tack this time around and has herded all major nations world-wide (there are exclusions for certain “developing countries”) into the dock for judgment and punishment. This time there is no country-specific element and it’s the US versus the rest of the world.

The issue at hand here is whether foreign solar companies who are able to import solar products into the US at less cost than the available domestic equivalents have an unfair advantage in the solar marketplace. The plaintiffs: Two large US-based solar companies.

The crying started in May last year when Suniva, which was 63% Chinese owned and now bankrupt, petitioned the International Trade Commission (ITC) that “increased imports were a substantial cause of serious injury to the domestic industry”. Suniva was later joined by SolarWorld Industries Americas, then a subsidiary of German owned and now reorganized SolarWorld Industries AG.

After much deliberation, our Robin Hood of Washington Forest has decreed that US solar manufacturers must have some sort of “safeguard” in order to compete fairly against foreign solar manufacturers, and these latest tariffs are the result. Whether this is a correct and/or fair judgment is up for debate, but I for one don’t quite understand how this is going to help the US solar industry much, if at all.

Paradoxically, those foreign solar manufacturers will not be paying any penalties, and our Robin Hood will not be robbing them and giving the proceeds to the now defunct plaintiffs. No, the tariffs will actually be paid by those US companies that import foreign solar products, and the burden will then be passed on down to the end user.

I had a bit of hard job the other day trying to explain the workings of a solar panel to a colleague, and it got me searching for a suitable analogy. Yes, there is the well-used comparison of water to electrical flow, but that’s a tad drippy and wishy-washy in my view, and I was looking for something more illustrative and fun.

So, how about this:

The owners of the Hylas 54, Genevieve, have a clever and beautiful solution for installing solar panels on their yacht that compliments her elegant lines, makes aft boarding via the swim ladder easy, and provides shade for the dingy when stored on the davits. All without adding extra weight on the back end.

Below is what they've shared on www.cruisersforum.com:

We wanted to add significant solar area but we were not keen on putting panels on deck (shading, slippery), on rail “wings”, or on the canvas bimini top (shading, dynamic substrate, complex wire routing, not useable when boat stripped bare for storage). We wanted a solution that looked in keeping with the existing boat structures and we did not care for sharp-cornered aluminum flat frame panel solution often seen.

We often get asked about the latest developments in solar technology, and when will they be available, if suitable, for boat applications. I am by no means a solar expert, geek would be more appropriate, but I do keep my ear to the ground and try to keep up with the latest developments.

The people at the National Renewable Energy Laboratory (NREL) make this a lot easier by publishing their chart (below) of research cell efficiencies for various solar technologies. This shows the state of play of the very best of the best cells available of each type of solar, measured by their efficiency, i.e. how much of the available solar irradiance is converted into electrical power. Here's a quick synopsis of the chart.

You and your boat are ready to join the solar revolution. Even a small solar panel can trickle charge your battery to keep it topped up. It is known that a battery kept fully charged has a longer life than a battery left semi-charged for an extended period.

When a manufacturer states their solar panel's power ratings, one must bear in mind that this is only a nominal reading. Unless power tolerance data is shown in the specifications, there is likely to be quite a range of possible power outputs.

Several of the solar panels we offer are made with genuine SunPower® cells which are only sold by SunPower®, directly to known manufacturers, who have passed their scrupulous inspection. And like many manufacturers, there are different grades of SunPower® cells - the higher the grade, the higher the price to the manufacturer, however the better the output. Solara and Solbian use only the geniune, high grade cells themselves on their SunPower® solar panels.

When looking at solar panels, ask to see the specification for the panels themselves. For example, Solara's Ultra glass panels show a power tolerance of -0%/+4.99%, so they are guaranteed never to be less than the nominal rating.

An essential component in the installation of solar panels on your vessel is a solar charge controller or regulator. This will regulate the voltage and current coming from your solar panels going to your battery. Most solar panels are 16-25 volts, so if there is no voltage regulation the batteries will be damaged from overcharging. Bear in mind that a fully charged 12v battery is around 12.7 volts at rest, but needs around 14.2 to 14.8 volts under charge. A solar panel has to put out at least that much voltage to be of any benefit, but if the panel voltage is not controlled and reduced it will cause serious battery damage.

Another point to keep in mind: solar panels provide power best when cool, under a clear sky, and in full sun; in other words in perfect conditions. But one can't count on that type of weather day after day, so solar panels have to be built to provide that extra voltage for when the sun is low in the sky, there is cloud cover, high temperatures, or heavy haze to ensure your solar output is not compromised. The truth is a 100 watt panel rated at per industry Standard Test Condition (STC) of 77oF and 1Kw/sq m irradiance will put out less watts when its surface temperature is 100oF degrees and when only 800 w/sq m irradiance is available, i.e. when it is in non-standard conditions.

So this is where the right solar charge controller can help. There are basically two types – PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking).

Coastal Climate Control now offers the very best in solar cable. But what does this mean?

Most solar cable available contains just 7 untinned copper strands, whereas ABYC requires a minimum of 19 tinned copper strands. The solar cable that Coastal offers is UV, sunlight, and ozone proof, and is extremely flexible due to the high number (100+) of tinned copper strands.

Minimum outside diameter and maximum flexibility are the keys to reducing the hassle of installing solar cable between the panel(s) and controller, and these cables are the very best we could find after an exhaustive search.

Available in AWG 12 and 5mm2 (AWG 10 equivalent) by the foot, or in cable sets with MC4 connectors already installed to connect directly with most types of solar panels.

Another great new solar offering from Coastal is the Philippi range of waterproof plugs and sockets. We are stocking a three-wire socket for attachment to the end of the cable from a solar panel, plus a corresponding three-wire plug to make a cable-to-cable connection. There is also a surface-mounted plug to make a cable-to-hard surface connection. (NOTE: Plugs and sockets are opposite to those found in homes, with the socket being on a flexible cord. The live, power-bearing component needs to be a socket for safety reasons.)

There seems to be many misconceptions regarding solar panels, particularly concerning marine installations on vessels. I’m thinking that maybe it’s because we all see solar panels on houses and assume that what applies to roof-top installations also applies to boats. Wrong!

Here’s some solar facts. Typical solar panels with silicon cells will:

• Produce electrical power whenever they are exposed to light, and this is proportional. Small amount of light - small power output.
• Produce full voltage even in very low light, often even indoors, but only if they are disconnected and not being asked to produce any power. Potential voltage output depends mainly on the number of cells. Each cell typically produces around 0.6 to 0.7 volts.
• Produce full current output only if there is a big enough load, the sunlight is good enough, and shading is non-existent. Potential current output depends on the size and type of cells.

In general; the quantity of cells determines voltage; the quality of cells determines amperage.

Now, what we are after in a boat solar application is to grab whatever power we can whenever there is available sunlight, and that means from dawn right through to dusk, not just at noontime. I often hear customers say that there is absolutely no shading at the back of their sailboat, but then when it is suggested that maybe in early to mid morning or mid to late afternoon, the presence of a humongous mast and associated rigging might shade a stern-mounted panel, they will humbly agree. From that sort of response one could deduce that many boaters are under the assumption that solar panels will really only work for a couple of hours each side of noon. Not so Horatio.

A while ago I debunked some common misconceptions about solar panels in another blog here, but it seems I missed one that has come to light several times recently, i.e. the myth that to have proper, serious, useable solar power on a boat one must use residential panels, as marine solar panels are just itsy-bitsy wimpy battery top-up trickle-chargers.

Nothing could be further from the truth!