Solar Panel Setup on a $500 budget for small Motorsailer Weekend Trips

For what it's worth, I have done multi-week trips including overnight sailing, running all those loads plus a tiller pilot, charging with a 60W panel and MPPT regulator (and of course the diesel), and about 100Ah of house battery capacity (was originally 150Ah but a few years old now). Battery voltage never a problem once I got things sorted.

So I'd say your 160 - 200W is very conservative. You don't mention your battery capacity, but I'd allow at least 80Ah to get you through cloudy weather.

Cheers, Graeme

I can most of the time get along very nicely with 300w solar and 140 ah battery, with no need for engine alternator input. I don't have a tv but run all you have listed & a fridge, charge battery tools etc. the trick is to go for led lights & other economic amp wise accessories. When cruising with the addition of vhf, nav gear & maybe a pilot, the above isn't enough, without engine charging as well. So perhaps your Diesel engine can help with the charge regime ?

Regarding the regulator, an MPPT will provide 30% more charge than a PWM from the same panel. Hence, given your boat is a small one, consider the weight and space benefits of being able to install 30% less panel capacity if you go with an MPPT.

The 30% figure is not just theory - I confirmed it when curiosity once got the better of me. I temporarily wired both on my boat with the ability to switch between them. Whether full sun or dull cloud, the MPPT consistently provided 30% more charging current.

Cheers, Graeme

I've never had much luck with flexible panels. Despite being very careful, they have died after 6 months or so. My rigid panels have been fine.

Mate, 300w of panels ( 150wX2) and a regulator for both batteries worked well on my boat to keep batteries full even I would often put my coffee mashine on. Coffee mashine was powered by 8000W inverter but alternator wasn't working. The best deal i Could find was at Jaycar.
Currently I have only 4Ah of charge on each batteries because I am not using inverter any more, and they are full as, always in floating state. Don't spend an enormous amount of money, I think that 5Ah on each battery = 10Ah x12 = 120W will be sufficient. So a solar panel of 120W and a regulator with dual exit ( 2 batteries) will do for you. A regulator is 39 bucks and solar is 140 in jaycar. Please don't buy nothing of internet or withworts ( claimed warranty 3 times on panels and regulators) till I left them there so they can have it. Honestly 180 bucks will charge your batteries and keep them full all the time. Alternator from your engine will also keep them sexy and panels will just keep them in floating state unless you are constantly using 10Ah and that is a lot for LED lights and bilge pump occasionally.

Use all the above info to buy a $410.00 system then use the other $90.00 to buy a lithium jump start battery. It's easier and quicker than push starting a boat!

In a nut shell Gazer, power generation and storage is measured in amps. Your 3x 120ah batteries = 360 amp hours, and I would suggest a nice moderate battery bank. Now to charging, if your 15 amp controller was able to supply at consistent full charge, every hour I would but in 15 amp hours, so if on a theoretical 10 hour full charge you could put in 150 amp hours. Now you need to look at the solar panel and see its theoretical output then the wind genys output. It gets a bit messy here so stick with me, solar panels and other charging devices are usually described in watts, without getting into math a 120w 12v panel = 10 amps and in 1hour it's possible for that panel to produce 10 amp hours. The problem with solar and wind is it's hard to calculate because the stats are for Goldie locks and reality is often less. Another thing to note is big batteries need big charging otherwise under charged batteries will have a shorter lifespan. Hope some of that makes sense

This is such a variable issue. Everyone who has a system will chime in and say it's the ducks nuts, but tbf, there has been some good info in the replies.
Here's my 2c worth having used 4 or 5 different solar setups over the last 15 years for camping and boating. 1. first thing is use LED globes or lights for everything; anchor light, steaming, nav, stern and cabin lights. Incandescent and flouro lights chew loads of juice.
2. Be wary of lithium on boats for two reasons. a) they don't have the CCA needed to start engines (but may be ok on smaller outboards) and b) the fire/explosion risk. I've used Lithium batteries for camping and they're great, but on a boat, I feel the risk is too much especially if you go offshore. I sell lithium powered skateboards and bikes and I have a healthy wariness of them from my experiences over the last 10 years +.without running a fridge, your biggest guzzlers of amps are VHF and Chartplotters. Mine pull about 1.3 amps each. 3. Batteries are important. Have enough capacity to not need top ups if you use all your loads for 5 odd hours over night. 4. When figuring out your load requirements, you need to assume the amps produced from your panels are at 90deg angle to the sun in the middle of the day on a clear day. Factor for low angles of sun on the panels, as well as cloud and part shade.
5. Use MPPT controller if you can afford it, they're just more efficient but cost way more than PWM controllers. Imho, they're still way worth it. 6. wire multiple smaller panels in parallel so if one panel gets shaded for any reason, the others continue to produce power. 7. Go with glass good quality panels, they maintain high performance and efficiency long after your third flexible panels have given up the ghost. I think flex panels are fine for emergency back up, but not as a primary use if they will remain on the boat out in the weather. I've just replaced lightweight cheap camping panels with quality glass ones. The lightweight cheapies last sbout 12 months before I had to spray them with a clear coat to make them translucent again. 8. search the Google for a solar calculator and be conservative in your estimations. Summer is a different beast to Winter in terms of solar power.
I have recently installed 390w of (3x 130w) high grade glass panels parallel wired through a 30amp MPPT controller feeding 2 x 105 AGM HD batteries. My boat is 28' and I can run tiller pilot, plotter/sounder, VHF with AIS, stereo fridge and nav lights on a partly cloudy day no problem and it is setup for weeks away from ext power.

FWIW hope this helps

DM

Done some digging and my current Steca PR1515 is not an MPPT. So at this stage am looking at a Victron BMV-700 Battery Monitor and 30 -40a/h MPPT controller so i can visually see SOC & other options. When i fly home from work I'll find out about the solar panel/ wind genny & their capacity.