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

Solar panels for yacht in the Med

Hello
Can you help me with some advice on solar panels. I have a yacht based in the Eastern Mediterrian, it has 3x 155amp/hr domestic batteries and a seperate engine batterry. I'm looking to try and keep the domestic batterries charged whilst sailing and at anchor. The main power user is the fridge which uses about 50amp hrs per 24hrs.
Currently I have a Sterling Power Management system which displays the battery position and amps being used and total amps consumed. This system counts down amps when on charge either by engine or mains charge.
To start with I plan hang them on the guard rail.
What would you recommend? Regards, Martin

Hi Martin,

Fridges do consume a lot of power unfortunately, so you would need a reasonable array of solar panels to replace what the fridge is using. As a guide, in the UK summer you would need about 120 watts of solar panels to generate about 50Ah per day (assuming you have a 12V system). As on a yacht it is difficult to keep the panels always pointing towards the sun, you may get a little less than that.

I would recommend perhaps a pair of Kyocera KC65 or KC85 panels http://midsummerenergy.co.uk/buy_solar_panels/kyocera_framed_solar_panels.html. They should certainly deliver most of the power you need for your system - perhaps not all, but then again you will be getting some power from the engine anyway from time to time. Dimensions are on the datasheets linked from the product pages on the website. We can supply the most appropriate regulator and suitable cables too.

Alternatively, we can get in some Sunware solar panels which can be attached directly to the deck, and can be walked on. They are rather more expensive than the framed panels, but if they would be of interest do let us know.

best wishes, Andy, Midsummer Energy

Solar propulsion for yacht

I'm considering design and building a yacht using only solar and wind generated electricity including propulsion. Comments/advice.Thanks,Dudley

It's certainly possible. Your difficulty will be storing enough energy to make it worthwhile. A yacht can motor on a diesel tank for weeks non-stop; even on a big bank of batteries it's going to be hard to get more than a few hours at a good speed. If you are content with a small engine that is only used for manouvering into and out of a marina at the ends of a longer passage under sail, I think it could well work. But don't expect to be able to do much in the way of passage making!