‘Green power’ is climbing up the priority ladder to such an extent nowadays that some predictions of fossil fuel costs (scorned at a few years ago), are coming home to roost.
We have chosen to be proactive and endeavour to be as reliant as possible on solar power as we possibly can. Our yacht carries a few more items such as additional solar panels and batteries which will surprise some and be talked down by others.
The electrical system has Solar Panels developing sufficient energy to charge three of the four Batteries to provide 12Vdc power to the vessel. Before embarking on its make-up a few things need to be clearly understood.
There is a reason that the Electrical Trade is a 4-year course in most countries and one can't read a 2-page document and be versed on all-things-electrical.
For the 'purists-in-electrical-know-how’, this may not be for you as there are phrases and words used here which may not be strictly correct in the your eyes.
We also strongly recommend that a qualified electrician be used in the connection of your vessels appliances. Your State legislation may require certification for systems over a certain voltage (or amperage) and some Insurance companies carry caviats against DIY Electrical.
If it all gets too heavy in reading, scroll down to 'POWER SUMMARY'
Replenishing energy (electricity) purely with proven techniques of small vessel power generation, comes with some form of ‘calculated risk’. A genuine decision has to be made on what we were going to use the boat for as this dictated the requirements and then build that into this 'Replenishment Risk'.
The most common forms of power generation on yachts include solar panels, generator/s (separate portable generator units), alternators (units making power from available and/or separate motors, usually the motors powering the boat), wind generators and water generators.
Why is it that one cannot locate a generic electrical system/diagram that can be used for their own electrical system on a boat? Its simple - 'Ask a butcher ‘how to plan Christmas day’. They could easily sell cuts of meat and sausages, but would have no idea on presents to buy, who to invite, ovens to use or even how to make a Christmas cake.
In the same way, each boat is different and all electrical setups are different and require different needs.
To calculate the initial electrical budget we jotted down all the components (including wiring) and tried to get an accurate honest figure. The result was not good. We bit our tongues and started to cut-down, after-all this was a yacht being built on a budget. It was either this, or build a bigger yacht to carry the energy and energy-makers.
Power Requirement Matrix
So, where do you start?
A 'Power Requirement Generator' (an App we hope to release shortly) allowed us to quickly change and modify (or more correctly, teach us) how to conserve energy and make best use of the power throughout the various parts of the day.
More importantly, the Electrical Matrix (a list of appliances with their associated volts, amps and wattage), gave us the power needed to meet our newly planned energy budget during various times of the day.
A good example can be found in our book, A Catamaran Building Adventure.
A clear understanding of Basic Electrical Jargon has saved many hours
of frustration in problem-fixing.
One of these understandings was the vessel power voltage of 12V DC over 24V
DC, as many more appliances and components are available that utilise 12V,
lowering building costs.
We jotted down everything that we thought would require power, even if it sounded silly and then went through a process of illumination, coming up with a ‘U-beat-wish-list’.
We say ‘wish-list’ as this is normally well over the top and some severe culling was required.
The advantage with 12vDC or 24vDC (in Australia), is that they do not require 'electrical certification' for the amateur builder. Other voltages need to be checked.
Bus Bars and Busses
So, what is a BUS BAR? A BUS BAR is a point of distribution, normally made out of a good power conductor, most commonly copper. Units are sometimes made from copper pipe however, in all instances, the greater the surface area for heat dissipation, the better.
In our build, we mainly utilise these on the negative side, providing a single (appropriately sized) cable directly to the negative side of the battery. In these lines there are no fuses/circuit breakers and also no switches. The positive side Bus Bars are the purpose built ‘Switch Units’ with their linked fuses/circuit breakers. We are no specialists in electrical design but have had our Bus Bars checked and rated for the ‘amperage’ given their dimensions and hole positions.
Or ‘best amperage guess’ fell within that calculated as ‘maximum rated’ and we deducted and additional 25% for peace of mind. We made two types, one to be used at the Main Bus point and the second smaller one to be used at the Nav station both rated at 300Amps for our 12vDC system. An abridged version of our 12vDC Electrical Diagram from our Books is shown below. Their names derived by the type of bus and position of the bus.
How many Busses should you have?
We ended up with 5 main Busses:
- Hot Battery Bus or HBB (linked directly to the battery and can be left on to certain essential switchable components at all times),
- Main Bus ('THE MAJOR BUS', where all the yachts DC electrical busses and DC electrical cables have their source – except the HBB above),
- Starboard Distribution Bus (distribution point for all DC starboard electrical)
- Port Distribution Bus (distribution point where a majority of the port electrical DC, Nav bus power, radios, hot water system and ships pumps have their source), and finally
- Navigation Distribution Bus (distribution point for all the navigation gear).