Keeping batteries topped up is an ongoing problem for sailboat owners. That´s what makes solar panels such a great solution: they put out pure DC power, making them ideal battery chargers.
However, it can be a bit of minefields, especially for the beginner. So whether you´re starting from scratch or hoping to make most of the panels you already have, this guide covers the basics, from working out how much power you use and need, to installing the panels yourself.
Working Out How Much Power You Need
It´s hard to predict how much sun you´re going to get during every season in locations like the UK and Canada. How much power will your panel produce if it´s not aligned with the sun, you might be thinking? Don´t worry, you can solve this and other solar panel riddles with a statistical approach and some established databases.
Start by adding up the energy in Watt-hours used by each device on your boat. Take a look at your fridge, lights, computers, etc. Most devices have a badge on them that will tell you what the power requirements are in Watts. Multiply that number by the number of hours per day that the device is turned on.
If this all seems a bit confusing, or you´d like a template to work with, here is an energy usage estimator worksheet you can use to calculate your vessel´s usage at anchor, and at sail.
Working out What Proportion of the Power Requirement Should be met by Your Solar Panels
Are you a liveaboard sailor, or a weekend sailor? If you´re a liveaboard, you might want your panels to supply a large proportion of your overall power. If you are a weekend sailor, your panels can be charging your battery all week to supply you with enough for a day or a couple of days sailing, and producing more power than you need doesn´t make too much sense!
Panels are rated as the electrical power produced under certain strict test conditions: solar irradiation of 1000W/m2 at 25C and an atmosphere of a particular clarity. However, you´ll need to assess the actual solar irradiation levels over the course of a day in your chosen location (more on that later!).
Go to Part 2 to learn about how to work out what type of panel to buy, the different types of panel available and where to put them. See you there!