how to do solar on a sailboat that has limited space and shading issues @48vnom

[HarryN]

I guess another possible pathway would be to use nominal 24 volt panels.

Charge a small 24 volt battery pack near them with a pwm controller.

Use a 24 volt in - 48 volt out DC - DC charger to feed the main pack.

Seems more complicated but it is a pathway.

 

[Ohms_Cousin]

Use a 24 volt in - 48 volt out DC - DC charger to feed the main pack.

There are losses in this approach as well - seems to be no easy way right now if one wants to charge 48vnom batteries.

 

[yabert]

charge 48vnom batteries

What will be the capacity? Do you plan big battery?

 

[HarryN]

There are losses in this approach as well - seems to be no easy way right now if one wants to charge 48vnom batteries.

The genasun approach is easy - it is just a money question.

 

[yabert]

The genasun approach is easy - it is just a money question.

Not just a question of money.
Genasun at 8A max is quite limiting when today 400-600W solar panels output 13-16 Amps.

 

[HarryN]

Not just a question of money.
Genasun at 8A max is quite limiting when today 400-600W solar panels output 13-16 Amps.

Smaller panels, more of them. The only issue is money.

 

[yabert]

Smaller panels, more of them. The only issue is money

Sorry, but no.
Smaller panels imply:
-More surface area for same output (caused of extra framings and lower cells efficiency)
-More weight caused by frames/supports, bolts and wires
-More wires management
-More points of failure caused of extra contact, crimp, etc.

Really, there is many downside.
Genasun boost MPPT would be an awesome product if it can take 20A

 

[Ohms_Cousin]

Sorry, but no.
Smaller panels imply:
-More surface area for same output (caused of extra framings and lower cells efficiency)
-More weight caused by frames/supports, bolts and wires
-More wires management
-More points of failure caused of extra contact, crimp, etc.

Really, there is many downside.
Genasun boost MPPT would be an awesome product if it can take 20A

quite right Yabert, quite right.

Smaller panels = more panels which as you point out, equals more wires management more pints of failure etc. It looks to me one either goes for high $$$ CIGS panels OR use a DC optimiser - if for no other reason then to be able to get a single panel on a single controller and still get 48v out of the setup.

 

[Ohms_Cousin]

What will be the capacity? Do you plan big battery?

I plan to install as many cells as will fit.

 

[yabert]

I plan to install as many cells as will fit.

really?
Considering all the potential free space in a sailboat, you could probably put 200 kWh.
The extra weight can be more preoccupant than space IMHO.

Personally, I consider 65-80 kWh to have a good range, but not too much extra weight.
But my plan is to first do some test next summer to know power requirement, regen capacity and so with a small 12 kWh battery.

At the moment, the only data I have is my 38' boat can do 3.7 knot with your electric dinghy motor (1.8 kW) with his tiny 10'' propeller and the data find online (image below).
Please share your design parameters and need if you have this.
Thanks

 

[IGBT]

I have the kw/speed curves for our 34 foot Pacific Seacraft somewhere. We have a 10kW electric inboard motor on it.

Edit: Found some data we made back when the hull was clean. This is a 16,000 pound sailboat with about a 7kt hull speed.

2.1 kts at 10 amps (500 watts)
2.5kts at 16 amps (800 watts)
3.2 kts at 30 amps (1500 watts)
4.5 kts at 80 amps (4000 watts)

 

[yabert]

I have the kw/speed curves for our 34 foot Pacific Seacraft...

Nice! Thanks to share.

 

[yabert]

I will probably end with 4 typical panels with split cells in a configuration 2 series of 2 parallel with two Victron 100/20-48

This thread force me to push the design a bit more.
Instead of four 400W panel, I will probably end with three 500W panel.
Two panels in series with a Victron 100/20 and the third one with a boost MPPT.

 

[Ohms_Cousin]

This thread force me to push the design a bit more.
Instead of four 400W panel, I will probably end with three 500W panel.
Two panels in series with a Victron 100/20 and the third one with a boost MPPT.

yes but will you wire in series to get the voltage UP to where you need it ? 48vnom is just not easy for solar on a boat !

 

[yabert]

yes but will you wire in series to get the voltage UP to where you need it ? 48vnom is just not easy for solar on a boat !

yes, exactly. As said:

Two panels in series with a Victron 100/20 and the third one with a boost MPPT.

 

[yabert]

48vnom is just not easy for solar on a boat

Depend of the boat

 

[TM48]

I need 48v on my boat as going for an all electric galley and I have 2 x 48v motors to run as an electric boat.

You better have a good generator. There just isn't enough real estate on any small boat for solar unless it's a dock queen.