Solar panel for motor sailer

I own a motor sailer with two 12v 110ah batteries in parallel i.e 12v 220ah. What size solar panel do you recommend and which regulator? The batteries supply all we need when fully charged so we are looking just to top up the batteries over a few days or so. Do we need to disconnect the panel when we use the engine and what else would we need.
regards Alan

Hi Alan,

If all you are looking for is a panel to keep the batteries topped up to keep them in good condition when you are away from the boat, then something like the Spectra 20 would be ideal, with a Sunguard regulator.

A 20W panel will give you about 8Ah per day in summer - although considerably less in the winter. So it will slowly recharge the batteries if you are away from the boat for a while. However, if you think you need to recharge batteries faster between uses, then you could go for a bigger panel. One of the Kyocera range of solar panels would be a good choice - they are available as solar panel kits with appropriate regulators included.

There is no need to disconnect the solar panel when the engine is running - the regulators are designed to work in parallel with other charging sources. Apart from the solar panel and regulator, all you need is some wire to connect them up! A fuse in the line is a good safety precaution - in many cases you can wire it up to an existing fuseboard.

Andy - Midsummer Energy