DIY: The Solar Solution

A DIY real-life solution to your power issues.

By Brad Roberts

Solar Basics

Sizing Your Custom Solar System

So let’s say, for example, that you calculate that you’ll need 1500 kilowatts of power per day on your boat between the coffeemaker, lights, stereo and TV. (To learn an easy way to do this, use the spreadsheet at https://www.microgreen.ca/downloads/Load-Evaluation-Sheet.xlsx) That means that you’ll need to add 1500 watts of power back into your batteries each day. Except that the sun doesn’t shine each day, so perhaps you’ll want to size your batteries to have enough power to cover your power needs for two days (so you don’t have to run the generator if you have one), and you’ll want to size your solar panels to produce enough power on the days that the sun does shine to charge the batteries enough to store two days worth of energy.  In this example, you’d need to generate 3,000 watts of power. The sun shines on average five hours per day in the summer. So 3 x 260watt panels = 750 watts per hour x 5 hours = 3,750 watts – more than the 3,000 watts needed. (Two panels would produce less power than you need.)
Plus, you’d need an inverter sized to the maximum power draw you’d be using at any one time – usually 2,000 watts on a boat (enough to operate a small microwave or coffee maker, but not at the same time), and deep-cycle battery storage for 3,000 watts. 
To correctly size the battery bank multiply the battery system voltage by the amp/hr rating and see what the total storage watts will be. For example two 6volt batteries for a 12 volt system times the 428 amp/hr rating would be 5,136 watts. You can safely use 50% of this which would be 2,568 watts.  If you need more power then add more groups of batteries. 

Building Our System

Summary

There is no question that as the world looks for alternatives to its reliance on environmentally-damaging fossil fuels and an escape from high energy bills that solar power is a very viable solution. One look at what Greenline Yachts is doing by integrating solar power into their lineup, and what Toqeedo is doing as they expand the horsepower range of their electric outboards, or Volvo’s commitment to electrify their power offerings by mid-2020, and you’ll see that the solar solution is within our sights in the marine industry as well, and as prices continue to drop as technology improves, it’s also within the reach of our pocketbooks.