Off the Grid – Solar Power, part 3

The following article has been contributed by a fellow prepper named Mike. It has been published with permission of the author. It does not necessarily represent the views of PreppingToSurvive.com.

This is the final post in a three part series on solar electricity. In part 1, I discussed solar power and how solar panels work. In the second part, I showed how you can calculate how much power you’ll need and how many solar panels will be required to fulfill than demand. In this last post, I’ll describe how to mount and wire your solar panels.

Mounting Your Solar Panel

Now that you have your solar panel, where do you mount it?  As we said before, mounting the panel 90 degrees to the southern sun is optimum.  You will get the best energy production this way.  But on boats, finding a suitable location is tricky at best.  I chose to mount our panel on the top of the trawler sundeck hardtop in a horizontal manner.  Here it will get the best view of the sun and be clear from the radar arch shading as the trawler turns at anchor.  The angle toward the sun in not exactly at 90 degrees but it will have to do.  I chose a 195 watt panel so I have almost a 50% reserve capacity in my panel to make up for the slight inefficiency of the sun’s angle.

If you choose to install a panel on land, consider mouthing it on rooftops or you may design and build a platform solely for that purpose.

Wiring Your Panel

Electrical wiring is very technical and hazardous; if you are not comfortable in doing this part of the task, please consult a qualified electrician.  Your panel will be prewired for attaching to your boat/house but you will need to supply the connecting cables that will also be sold by your panel supplier; they are referred to as MC4 cables.  The cables will come in different lengths suitable for your needs with a male and female connector attached; you cut one connector off.  (The photo shows how we have our modified solar/wind turbine system wired.)

In addition, you will also need a controller.  The controller regulates the electrical flow from the panel to your batteries keeping your batteries charged yet preventing over charging.  Some controllers are simple but others have LED displays showing the rates of charge etc.  The more whistles and bells the more expensive it will be.  Your panel supplier will be able to recommend a controller that will meet your needs.

I chose a controller made by Specialty Concepts.  It is simple yet does the job.  And the folks at the company are a big help in helping you choose the right model for your desired panel.  When you contact them, the will need to know what size panel (wattage) you are buying and what the voltage is.  Check them out at www.specialtyconcepts.com.  I also bought my controller from the people at Sun Electronics in Miami.

And lastly, you will need the appropriately sized cables to run from the controller to your batteries and a fuse to hook the controller to the battery bank.  In selecting the correct fuse, you will need to find the short circuit current for your panel and rate the breaker at 125% of that number.  The short circuit rating will be found on the panel specifications.  This will give you the amperage of the breaker you will need.  Your controller operating manual will have guidance on these too.

Having a solar panel to maintain your batteries seems like a great idea but you’ll need to have a way to monitor your batteries.  I chose to also install a Trimetric 2025RV Battery Monitor; www.bogartengineering.com .This smart device is wired into your battery bank to give a real time measurement of voltage going into the bank, amps being used by your boat, the percent full charge on the bank, and the amp hours used since the last charge.

Panel Operation

So we have now installed a 195 watt solar panel coupled with an 1800 watt inverter and a battery bank with 443 amp hours aboard our boat.  We ran our tests at anchor with clear skies.

Using the worksheets attached I concluded that our power consumption is 112.5 amp hours per 24 hours.  The freezer alone is the biggest draw using 60 of the amp hours followed by the refrigerator.

On a clear Florida summer day, the solar panel can supply 100% of the boats needs from sunup to sundown; we only lose approximately 40 amp hours overnight, but the panel will bring it back to full after a few hours of sunlight.

When relying upon alternative energy, you must always be aware of your surroundings and how much energy you are consuming.  For instance, our previous anchor light consumed 20 amp hours in a 10 hour period; replacing it with an LED light uses only .2 amp hours.

When the SHTF, I think we’ll be able to maintain our lifestyles to a relative degree of normalcy.

In future articles, I’ll discuss how to choose an inverter and how I have supplemented the solar panel with a wind turbine.

Fair winds,

Mike

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