Insist on only genuine, high-grade SunPower® back-contact solar cells
- Category: Solar
SunPower® back-contact solar cells are currently the highest efficiency cells available for use in everyday applications at 22%+ rated efficiency. But they can be expensive and difficult to purchase. Genuine high-grade SunPower® cells are only sold to prestigous manufacturers in a few select markets, and significant quantities, a minimum 10,000 cells at a time, must be purchased by the manufacturer to ensure a workable price for their customers.
It has recently come to light that some back-contact cells made by SunPower® have found their way on to secondary markets and into panels originating primarily in China. Rejected by SunPower®when they failed their rigoroustesting, these faulty cells cannot carry the prestigious SunPower® name due to their substandard quality. Unfortunatley, some promotional material we’ve seen brazenly disregards this fact.
Be wary of any solar panel with back-contact cells that does not explicitly make reference to the cells as being genuine, high-grade SunPower® cells.
Be wary of solar panels with multiple circuits!
- Category: Solar
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.
Solar charge controller, what is it and do I need one for my marine solar panel installation?
- Category: Solar
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).
Solar Tax Credit and Your Boat
- Category: Solar
The US Federal Government offers a solar energy tax credit, applicable to your second home, i.e. your boat! As long as there is a head and galley onboard and it is docked in the United States, your vessel qualifies. This tax credit, extended to December 31, 2019, is a 30% credit on qualified expenditures to purchase and install solar panels, with no maximum limit for equipment placed in service after 2008. In the last few years, we hear at different boat shows the success stories from boat owners getting that 30% tax credit. This credit can be retroactive – as long as the solar system was placed into service after January 1, 2006.
Check out this updated link to the Dept of Energy's website that gives a simplified description of the energy tax credit: http://energy.gov/savings/residential-renewable-energy-tax-credit. Want to see how simple the actual IRS form is to fill out: http://www.irs.gov/pub/irs-pdf/f5695.pdf. Your state government may also have a solar tax credit. It may be worth investigating.
Life has become so much easier for so many people since they took advantage of this tax credit. If you want solar power on your boat, it may have just become more affordable. There is still time to plan and implement your solar power project, but I wouldn't suggest waiting too much longer – December 31, 2019 will be here before you know it! Contact us at www.CoastalClimateControl.com about your marine solar system.