diy solar

diy solar

Old Boater, new challenge

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Desperado

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Mar 25, 2020
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I've been living on and restoring a midsized motor yacht for several years and am ready to add some solar capability to my electrical system. Solar power is new to me and I have spent quite a bit of time on line watching videos and researching component parts. So far the current plan is to get a basic 24V system going and adding output capability as necessary. I have settled, I THINK, on the basics as follows;
1) Two series connected Oasis Firefly 12V/116A G31 (carbon foam chemistry) batteries.
2) Two Renogy 160W monocrystalline PV panels also in series.
3) One Outback Power 80A MPPT controller, and 4) the required switches, fuses, and busses as necessary.

The boat has a 13 X 14 ft unshaded flybridge roof with a projected vertical distance of 22ft from panel mounts to battery bank adjacent to engine room. There is a 30kva genset aboard but it's noisy as hell and drinks too much. I would like to get off the grid amap while retiring the genset to backup duties.

Would welcome any advice, input, suggestions etc on the above component parts, specifically compatibility.
Thanks to responders. Rodd
 
Id swap the controller for a victron 30A. 2 160w panels you will be lucky to see 20A. More like 15-17a. 80A is comically over the top. I would take the savings and go for 1-2 more panels.

I dont know anybody using firefly batteries so I just cant comment.
 
smoothJoey said:
Why did you go with carbon foam batteries?
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well i'm by no means a battery expert but I liked what I read about the construction characteristics in that its a new technology which somewhat approaches lithium features at less cost. Havent bought them yet however. Casting for opinion.
 
Ped said:
Id swap the controller for a victron 30A. 2 160w panels you will be lucky to see 20A. More like 15-17a. 80A is comically over the top. I would take the savings and go for 1-2 more panels.

I dont know anybody using firefly batteries so I just cant comment.
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The initial panel and battery count is just a starting point. I'm positive I'll want more power than a couple of 160's will supply and space is not an issue. I am however having some trouble arriving at a power usage number so I thought I'd start minimal to see what I got anticipating the need up build. That's why I am considering the 80A controller. Thanks for your input. PS. Carbon foam technology seems to minimize sulfation and thereby increase cycles. So they say...
 
Id still go with victron. You can parallel multiple controllers, fyi. You dont have to have one big one. In fact its better to have multiple strings due to shading issues and component failures.
 
Desperado said:
well i'm by no means a battery expert but I liked what I read about the construction characteristics in that its a new technology which somewhat approaches lithium features at less cost. Havent bought them yet however. Casting for opinion.
Click to expand...

If the cycle estimates are accurate Lifepo4 is a pretty good value.
www.mobile-solarpower.com

Raw LiFePO4 Cells

LiFePO4 BMS can be found by clicking here
www.mobile-solarpower.com
 
Ped said:
Id still go with victron. You can parallel multiple controllers, fyi. You dont have to have one big one. In fact its better to have multiple strings due to shading issues and component failures.
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Well you certainly make a good point about the use of multiple controllers and I understand the benefits of multiple strings. In my case I expect shading issues to be practically non existent since the arrays will be mounted at the highest point of the boat. So planning around shading issues is not a priority. Am I correct in the understanding that each string requires its own controller? And each string is limited to a value that will not exceed the rating of the controller?

I have considered a Victron controller (and others) but made the Outback choice in part because of the remote feature (the controller(s) will be mounted below two decks). Why do you feel Victron would be a better choice? Thanks again for your input.
 
Cause theyre a company making things no one else is and theyre all integrated.
 
Are you integrating with the boat's existing 24V DC house system or will the solar be used only for AC with an inverter?
If I understand it correctly the Oasis Firefly are AGM batteries. At this time I see no reason to go AGM versus lithium anymore. Not for price, performance or longevity. Only if you are dealing with a lot of sub-freezing temps does lithium (LIFEPO4) get troublesome. What type of climate are you dealing with?
You say you don't have a handle on your load but when is it that you have to fire up the genset? You realize that heating and cooling are out of the question with solar (or at least your size solar) -- right?
 
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Integrating with a 12v system. Significant AC on the boat. I know I can't run air but need that TV and microwave, probably instant on hot water on the AC side. Firefly is AGM but I'm not stuck on them. This boat won't be operating north of the Suwannee River, but most likely in the Bahamas. Been looking at LI's this evening and notice significant price differentials for a given rating (12v 100 to 170A). At this knowledge level I'm assuming that is because of incorporated features. I've looked at Victron, Relion, and Renogy batteries and it seems that their LI's don't like series connection. Am I correct about that?
 
As I mentioned the DC on this boat is 12V. But I understand that 24V bank(s) are more efficient and require less wire AWG than 12V. The Victron Smart 12/24V-30A controller looks suitable and surely would be compatible with a Victron battery bank. On the other hand Renogy has a smart controller which no doubt would be compatible with their 160W panels. Whatever components I decide to use I still would want to start small and add on over time.
 
Desperado said:
Integrating with a 12v system. Significant AC on the boat. I know I can't run air but need that TV and microwave, probably instant on hot water on the AC side. Firefly is AGM but I'm not stuck on them. This boat won't be operating north of the Suwannee River, but most likely in the Bahamas. Been looking at LI's this evening and notice significant price differentials for a given rating (12v 100 to 170A). At this knowledge level I'm assuming that is because of incorporated features. I've looked at Victron, Relion, and Renogy batteries and it seems that their LI's don't like series connection. Am I correct about that?
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W.R.T. the Relion batteries, If you go to the FAQ for their RB300 [ https://relionbattery.com/products/lithium/rb300 ] they answer your question about Series and Parallel connections for that series. Also, they offer an RB300-HP [ https://relionbattery.com/products/lithium/rb300-hp ] that are dual-purpose that can handle both starting (increase in peak amps) and cycling. So after starting, the battery can double as a house battery. I‘m considering using these for my boat.
 
Old boater, I’m also a newby but a live aboard sailor. Panels are fairly cheap. I’m currently running a 300 watt panel on the Bimini and four Trojan T105s. Yes, they are wet batteries.... I replaced failing AGM batteries with wet. I’ll stick with wet until the leading bleeding edge gets sorted out. The previous owner constantly drained them and they over charged them. (We found a custom setting on the Balmar floating at over 15 volts) I also have over banked my batteries. Im told that if we keep wet batteries above 60% and Keep them hydrated, they will last many more years. We as mariners have more options than most land based installations. The house I live in part time has an outback controller... I used them also in Africa. Land based they are awesome.... but not what I’d use on a boat. For the price of the outback, you could go with MPPT controller, and a Balmar 95 amp Alternator. (I have a balmar installed for cloudy days)
I'm not sure what your amp hour load is, mine is a small 12 volt refrigerator and lights. Water maker only runs when the engine is running. Electronics are minimal but I am likely to bump to two more Trojans making The two new ones the start bank while sailing and switch as part of the house bank at anchor. Cheers and good luck! You might want to check out sailors and cruisers forum. They have a lot of threads on solar. Cheers!
 
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