Saturday, 29 November 2014

Boat Improvements (2)

As always things in life undergo gradual change. This started me thinking about what changes I could make to the boat to improve life aboard.  Because our requirements have changed with retirement. From long weekends and occasional holidays. To spending a great deal of time on the boat but not quite as live-a-boards. 

My old boss had a rather interesting question that he put to the staff meetings. It would go something like this - "I know that we may not all be happy working here. But if there was one thing that you could change to make things better what would it be." Over the years some changes were made to working practice as a result of ideas being expressed.

Like my old boss, I would never make a change just for the sake of it. There would always need to be a tangible benefit from making any change. Since we purchased the boat, we have made a few small but significant changes. In this instance because of the readily availability of a new technology. 

Following on from Boat Improvements (1)  I shall describe some other changes that we have made to Rosie while we have owned her. 

Sometimes when we were out but moored up for an extended period we would have to run the boat engine to recharge the leisure battery bank. Wherever possible we would try to synchronise our boat movements to the need to charge the battery bank. I this respect we were fairly successful in our endeavours. Now that we are retired and there is less impetus upon us to move. We needed to look at alternative ways to charge the battery bank.  

Three very different methods came to mind. We could use a separate petrol generator. There was also the possibility of wind generation as well as solar generation. I spent a great deal of time exploring each one. I eventually settled upon solar generation as the best way forward. Each system has its own benefits and pitfalls. Solar gave the best alternative option in our particular circumstances. 

Solar panels  are improving their efficiency almost daily and come in several different types.
Monocrystalline and Polycrystalline Solar Panels are the most easily available.

Typically solar panels also have a long operational life. Plus they have no moving parts. A long warranty period is typical for most solar panels. Reputable solar manufacturers produce solar panels with a 25-year long warranty. 

Monocrystalline: Monocrystalline solar panels have the highest efficiency rates and are in the region of 15-20% conversion efficiency.  Last but not least they perform better than other solar panel types in low-light conditions.
Polycrystalline: The efficiency of polycrystalline solar panels  are improving almost daily and are typically around the 13-16% mark. These are the cheap as chips panels to purchase.
To all intent and purposes you can ignore the information above as panel manufacturers build their panels to conform to certain output ranges. the main difference being the physical sizes of the panels. Usually described in watts  typical panel values being 80 and 100 watts.  The anticipated output will vary depending on the amount of sunlight falling on the surface of the solar panel. In over cast conditions the panel output will be reduced when compared to bright sunshine on a cloudless day. 

Panel Wiring Diagram.

At the time we purchased 3 80 watt solar panels. This gives a theoretical top figure of about 20 amps. However, because we are well north of the equator, in good conditions the three panels tend to peak at around 12/15 amps.However, on a typical summers day the figure is around the 8 amp mark. In the winter months the typical clear winters day figure is around 2/4 amps. Another point to remember is the length of daylight hours varies from summer to winter.

Controller Connections

The next important bit of kit that you need is a device to control the panel. A solar charge controller or solar panel regulator is an essential component of most solar charging systems. This device sits between the solar panels and the battery bank.  There are standard PWM (Pulse Width Modulated) controllers and the more advanced MPPT (Maximum Power Point Tracking) controller. The MPPT controller improves the charging efficiency of the solar system by up to 30% so it is an easy choice to make.

Its almost three years (February 2012) since we installed the controller and panels.  The MPPT controller has in that time recorded adding 18723 Ah (Ampere Hours) into the battery bank, averaging 19ah per day.

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