Adding Solar Panels - Looking for best practices

[mitiempo]

Originally Posted by RSB333

.......Would running the panels in series -increasing the voltage - through a single larger controller be advisable?

Only if there is zero chance of shading of one of the panels. On a sailboat that is very unlikely.

[Paul L]

We have a mix of hard panels and flex panels onboard. Hard panels on arch, flex on bimini. We are on our second set of flex panels as they don't last as long. First set lasted 3 years. For the second set we purchased aluminum backed panels. These have a longer life than the plastic backed panels. They are still working fine after 4 years.

[Mahayana]

Originally Posted by Ded reckoner

We have rigid panels, but an acquaintance indicated they were well into their third year using flexible panels mounted on their bimini. The panels were held down using Velcro. The panels had never been removed for any reason including high winds.

+1. We had four 100W semi-flexible panels hook/looped to our bimini in 2016. While they have some "sunburn" issues they still perform (inspected by solar engineer in Sept 2020). Only removed for high winds and at winterization. Planning to add two rigid panels to the aft lifelines. More solar is better, just have a hard time deciding where as we have a center cockpit with few choices for installation and prefer not to add structure to the davits.

[JamesPNW]

Originally Posted by bcboomer

A better alternator is available from these guys at a reasonable price.



http://www.all-tek.ca/marine-brushless.html



I've been using their 200 amp model for 2 years with a Wakespeed regulator with good results. The alternator was only $320 CAD.

Thank you for the ALT information

[antoha]

i have a 100 Watt chinese semi-flexible panel i bought from a fellow forum member in 2013. it's a 20 Volt open voltage panel / 17.8 Volt max current, and i have it connected via a PWM controller (Morningstar Duo, which allows me to charge both battery banks). per specs, this means 5.6 Amps and this is what it was when the panel was new. performance was probably deteriorating slowly but i got 7 years out of it with minimal degradation.

they are supposed to be step-on panels but i have been avoiding doing that. they are not kid-proof though, so after last summer with a bit more foot traffic on the panel i only get 3.6 Amps out of it, with the same controller.

oh well. it will be a maintainer panel now. still, given space and "looks" constraints (the boat is a 1968 plastic classic, with no davits or arch etc), i am pleased with this solution and quality of the panel.

anton

[antoha]

this is my install from 2013.
anton
p.s. sorry, not sure why it rotated the image and how to unrotate it.

[Lost Horizons]

Originally Posted by Paul L

For the second set we purchased aluminum backed panels.

What are they? Brand, model? How thick is the aluminum plate?

[Adelie]

Originally Posted by RSB333

We are adding flexible panels to our Bimini this year, and we're looking for the latest techniques and advice. Will also replace our FLA batteries with two T31 AGM's and plan to install a Sterling "Alternator - to - Battery" charger to boost the output from our 55 amp original equipment alternator. We haven't been able to run our Adler Barber refrig. in the past as the drain on the batteries was unsustainable. But with the new system we plan a 100 AH daily electrical usage. Your advice and comments welcome!

Why AGM? Realization that you won’t be good about checking water levels in FLAs or because of poor access or both? T31 is a Trojan I presume. Trojan FLAs are cheaper and will last longer. https://www.cruisersforum.com/forums...ml#post3316640

Additionally AGMs really need to be charged hard if they are drawn down near 50-70%. At the minimum they should be charged at 0.2C which is 40A for your planned 200Ahr bank. 0.3-0.4C would be a bit better for them. Your existing alternator could do 0.2C. If you increase your bank size in the future then the existing alternator will be undersized.

As you increase your alternator size at some point you will need to change the belt and pulleys to a serpentine system. The stock belt won’t be able to push the alternator without slipping somewhere. All the pulleys on the engine, alternator, water pump and whatever will need to be replaces so a wider multi-groove belt can be installed.

With your stock 55A alternator it probably degrades to 45-50A when it gets hot. Assuming you 200Ahr bank is discharged to 50% the alternator will run for about an hour before it becomes voltage limited and current tapers off for the next 4-6hr.

Let’s say you have a 120A alternator that degrades to 100-110A as it gets hot. Starting at 50% it will run about 30min before it becomes voltage limited and current tapers off for the next 4-6hr.

The higher output alternator is going to save you 30m engine runtime per day. Frankly, once the bank becomes voltage limited the engine should be shut down and panels should finish the long slow part of charging which is what they are really good at.

With an expected 100Ahr/d draw the 200Ahr bank size is very marginal. 300Ahr would be decent for long term, good if you were just staying aboard occasionally. 400 would be good off shore.

Regardless of bank size or battery type, the best time to run the engine alternator or a generator is first thing in the AM when the batteries are lowest. That’s when the highest amperage can be accepted. Late in the day is probably worst unless you run to power a specific high load task like a microwave, watermaker, water heater.

I’m inclined towards hard solar panels for the increased output per area. I would maximize installed wattage in the Bimini. Better cost and longevity are in their favor too.

On the Bimini the panels should be split port and starboard since shading tends to be on one side or the other. Each panel should get its own small controller to minimize shading effects.

My rule of thumb for consumption is 50Ahr/d per fridge and the same for an autopilot run 24/7. On a larger boat it’ll be more like 75Ahr/d.

Regarding your fridge. If I was running the engine I would turn the temperature as much as possible while it was running then reset when the engine shuts down. I would turn down the temp late in the afternoon when batteries are full or almost full and there is excess power from the panels then reset the temp about sunset. There are some fridges that have voltage sensors to know when power is plentiful and automatically drop the temperature setting.

I’m not real clear what the Stirling thing does. It looks like it controls a stock alternator with internal regulation by manipulating the voltage the alternator sees rather than replacing the regulator. It’s not going to get extra power out of the regulator.l than it’s rated at. If it tries to it seems likely the alternator would get burned out.

What I would do is add solar and see if your fridge work right with that in place. Depends on how big the current house bank is. If you already have 200Ahr of FLAs indecent condition you might be fine with just that.

[Paul L]

Originally Posted by Lost Horizons

What are they? Brand, model? How thick is the aluminum plate?

Just a no-name brand ordered off Aliexpress and shipped from China. Cheap. For flex panels I think you are better off buying the cheap ones. You can replace them twice over 8 years and still be way cheaper than the high end flexpanels.
The aluminium backer is maybe an 1/8 in or so.

[bcboomer]

I went high end with 2 faced Gioco because there was a deal here on CF.
The panels were only part of the overall cost. If I were to do it again I'd probably go with cheap.
I put a curve in the frame for the panels so they don't flutter. That should make them last.
A bigger, robust alternator will solve any charging issue and, if the budget allows, seriously look at Firefly. Less expensive on the long run.

[hlev00]

Here's a post I made about installing Solbians on our bimini.
https://www.cruisersforum.com/forums...no-238690.html

The amount of velcro we used holds them in place quite well, but also are pain to mount in the Spring. If you do lapel / flaps like this try to have the flaps be either all hooks or all loops to prevent them from grabbing each other.

I would be concerned about cheap flexible panels. There have been a few fires started on biminis expected to have been caused by shorts in the panels. I suspect any panel is subject to this sort of failure but I feel more confident in the Solbians.

harry

[David B]

Originally Posted by RSB333

We are adding flexible panels to our Bimini this year, and we're looking for the latest techniques and advice. Will also replace our FLA batteries with two T31 AGM's and plan to install a Sterling "Alternator - to - Battery" charger to boost the output from our 55 amp original equipment alternator. We haven't been able to run our Adler Barber refrig. in the past as the drain on the batteries was unsustainable. But with the new system we plan a 100 AH daily electrical usage. Your advice and comments welcome!

We have semi-flexible panels on our curved equipment arch.
They are now in their sixth year of service and still going strong. I suspect the issues some have with semi-flexibles is cooling. When they are fixed straight onto a deck, they are going to get very hot!
Having the underside exposed (free on an arch, or nearly free on a bimini) is the difference.
Our panels are aluminium rather than composite backed, and that no doubt helps.
We intend extending our system to two large semi-flexbiles on the bimini, but just waiting another year or so in the hope we can get 400-500W per panel

Also, regarding your battery move, have a look at this before you go for the AGM's. We are staying with FLA's, and this video confirmed our decision for now.
https://youtu.be/LPPUqLZOqCQ

[RSB333]

Originally Posted by bcboomer

A better alternator is available from these guys at a reasonable price.

http://www.all-tek.ca/marine-brushless.html

I've been using their 200 amp model for 2 years with a Wakespeed regulator with good results. The alternator was only $320 CAD.

Thanks for the reference. 200 amps of output seems like a lot for my little 21HP diesel.
What size is your engine?
RSB333

[bcboomer]

I have a Westerbeke W46 - 43 Hp I think.
They have lower output alternators available and the WS100 regulator gives lots of options to reduce output when you need more engine power.
You can select 90, 75 or 50% output an it has a delay on start up so the engine isn't loaded up right away.
They have a more sophisticated one now too for more $$$.

[Andrew Lippman]

I added Solbian flexible panels two 78W and one 118w with Victron controller. Since this is an MPPT controller, the panels are in series to get high enough voltage for my 24v system. They provide enough energy to keep the refrigerator running all season in New England.

These flexible panels are ungodly expensive. No idea of longevity but at their prices I am hoping for the best. Victron is top grade.

A friend has a more elaborate system with a controller/panel. That is clearly better but entails more wiring and more money.

Of course you understand that batteries do not generate energy, they just buffer it. If you need to run the engine two hours to charge, a bigger battery just means two hours once a day versus one hour twice a day. (This is not quite true, since charging is not linear, but close enough...)

There is no doubt that hard, fixed panels are far better, but I generally see those on boats with davits and fixtures on which to mount them.

Best, Andy