Houseboat Off Grid Solar System (Newbie)

[BigMike701]

OK, new to off-grid solar so please bear with me. We just purchased a fixer-upper houseboat (basically an RV on pontoons) and it has no shorepower available. It came with (2) 100a solar panels and (4) 12v lead acid batteries, no inverter, and a 3,000w generator, with a 50a charger for the batteries. The 120v only works with generator running and there is no 240v system. I am building a new solar system from scratch. The approximate max demand usage is around 2,800w at any given time (summer running a/c's etc). I would like to be able to run on solar/battery only day and night (generator only for low-sun days). The days in the summer hover around 110*+ during the day and can stay as high as 90*+ at night. Located in Central California.

My system parts so far:
(1) EG4 3kW Off-Grid Inverter (5,000w PV input / 500 VOC / 80a charger);
(6) 450w SunGoldPower Mono Panels (41.72v / 13.82a)(2,700 total watts);
(4) LiTime 12v 200ah (200ah bms) Batteries;
(1) Victron Smart Shunt Battery Monitor;
(AN) 10awg PV wire (from panels to Inverter) The inverter is about 50+ LF away from the array;
(4) 30a MC4 inline fuses;
I feel like I am "under" paneled and/or under storage. I have room for 4 more panels (4,500 total watts) and 4 more batteries (8 total) if needed.

Now for the stupid questions.
1. Would it be better to run the panels in series or parallel or both? The inverter has an 80a charger. Do I need to run higher amps to get higher amp output to charge the batteries or does the inverter take care of that, allowing me to run in series and thus utilize smaller wire?
2. What size Class "T" fuse would I need?
3. Solar disconnect recommendations?
4. What is the max recommended distance (LF) from the batteries to the inverter?
5. What is the max recommended distance (LF) from the inverter to the load center?

Thank you in advance for you advice!

-Mike-

 

[pvgirl]

1. With that inverter you will need to run those panels in series as the inverter has an 18 amp limit on the solar input. 80amps is the output current.
2. 100 amps
3. IMO makes good disconnects: https://signaturesolar.com/dc-disconnect-rooftop-isolator-switch-by-imo/
4. as short as possible, longer distances may require up sizing wire to minimize voltage drop.
5. distance shouldn't be an issue on a house boat. if you are worried do a voltage drop calculation.

With just 4 panels you are very close to minimum voltage need for the inverter(120volts), I would highly consider adding more panels, you can add 4 more and stay under the voltage limits. With just one string of panels no fuses are required on the PV circuit.

Depending on power draw of the AC unit you want to run you will need a much bigger system if you want to run the a/c all day and night. If possible you may want to consider adding insulation, or converting to a more efficient mini split system to reduce the power demand for ac cooling.

 

[Skypower]

At least consider the smallest mini split you can find for the stateroom so you can sleep comfortably. Insulate the windows with cut to size, push in place insulation.

 

[BigMike701]

1. With that inverter you will need to run those panels in series as the inverter has an 18 amp limit on the solar input. 80amps is the output current.
2. 100 amps
3. IMO makes good disconnects: https://signaturesolar.com/dc-disconnect-rooftop-isolator-switch-by-imo/
4. as short as possible, longer distances may require up sizing wire to minimize voltage drop.
5. distance shouldn't be an issue on a house boat. if you are worried do a voltage drop calculation.

With just 4 panels you are very close to minimum voltage need for the inverter(120volts), I would highly consider adding more panels, you can add 4 more and stay under the voltage limits. With just one string of panels no fuses are required on the PV circuit.

Depending on power draw of the AC unit you want to run you will need a much bigger system if you want to run the a/c all day and night. If possible you may want to consider adding insulation, or converting to a more efficient mini split system to reduce the power demand for ac cooling.

Thanks for the advice. Just ordered the solar disconnect and Class T fuse. However, I have (6) panels and (4) batteries. Underpaneled/storage?

Mike

 

[pvgirl]

Thanks for the advice. Just ordered the solar disconnect and Class T fuse. However, I have (6) panels and (4) batteries. Underpaneled/storage?

Mike

That will depend on how much that loads you want run will consume over 24hrs, and if that can be covered by the 10kwh in your batteries.

 

[Rocketman]

Max the size of solar that you can get on the boat. Every panel will reduce generation run time. Yes I think you are light on panels.

Also, does your boat have a 12v system too? You will need panels and a SCC to charge those up too. (Unless you go with a 48v to 12v converter.) You probably want to delete the lead acid batteries and add a second lithium 12v system. The 12v batteries need a Smartshunt too Or maybe the BMV712 might be better because then there is a screen to look at. I would really suggest going all Victron- but it looks like that ship already sailed, lol.

Do those 12v batteries start anything? Generator/motors? If so maybe keep the lead.

Remember plan out what happens in all the different failures. If someone leaves the A/C on too long and the battery shuts down - how does that impact the boat… etc.

Good Luck

 

[BigMike701]

Max the size of solar that you can get on the boat. Every panel will reduce generation run time. Yes I think you are light on panels.

Also, does your boat have a 12v system too? You will need panels and a SCC to charge those up too. (Unless you go with a 48v to 12v converter.) You probably want to delete the lead acid batteries and add a second lithium 12v system. The 12v batteries need a Smartshunt too Or maybe the BMV712 might be better because then there is a screen to look at. I would really suggest going all Victron- but it looks like that ship already sailed, lol.

Do those 12v batteries start anything? Generator/motors? If so maybe keep the lead.

Remember plan out what happens in all the different failures. If someone leaves the A/C on too long and the battery shuts down - how does that impact the boat… etc.

Good Luck

Rocketman,

I have ordered an additional (4) pannels to max out the capacity of the EG4 inverter and the additional (4) 12v 200ah batteries. Yes, there is a seperate 12v system which runs the refrigerator (ignitor & control board only, LP powered), 12v lights, 12v water pumps, and 12v sockets throughout the boat. I do have a 48v to 12v 50a stepdown transformer to power those items. The Victron Smart Shunt I mentioned in my original post is the BMV712 Smart Battery Monitor, LOL.

Thanks for your help!?

Mike

 

[BigMike701]

Thank you everyone for your quick assistance! My system now consists of, so far ? :

1. (10) 450w (4,500w), 41.72voc (417.20voc), 13.82a Panels;
2. (8) 12v 200ah (200a bms) batteries (2) 48v banks;
3. (1) EG4 3kW Off-Grid Inverter (5,000w PV input / 500 VOC / 80a charger);
4. (1) Victron Smart Shunt Battery Monitor;
5. (AN) 10awg PV wire (from panels to Inverter) The inverter is about 50+ LF away from the array;
6. (2) 5 to 1 Solar branch connectors (1 on the pos leg & 1 on the neg leg);
7. (4) 30a MC4 inline fuses (just in case);
8. (1) IHO PV array disconnect;
9. (1) Blue Sea Systems - 100a Class "T" Fuse with holder;
10. (2) Blue Sea Systems - 4p Buss Bars (1 pos & 1 neg);
11. (1) 48v to 12v 50a stepdown transformer (for existing 12v systems);
12. (2) 12v 120mm high flow cooling fans (1 inlet and 1 exhaust) for battery box;
13. (1) 12v programmable digital thermostat switch (dual display) for cooling fan control;
14. (1) Blue Sea Systems Battery disconnect switch;
15. (1) Victron Ekrano GX System Monitor;

Please let me know if I am missing something. This should more than cover the needs of the houseboat.

Thanks again everyone!

Mike

 

[pvgirl]

6. (2) 5 to 1 Solar branch connectors (1 on the pos leg & 1 on the neg leg);

For your inverter you will want to run all 10 panels in one series string. Branch connectors are only used when panels are run in parallel, and aren't needed and shouldn't be used with your inverter.

7. (4) 30a MC4 inline fuses (just in case);

Not required.

Please let me know if I am missing something. This should more than cover the needs of the houseboat.

Everything else looks good.

 

[SparkyGage]

Max the size of solar that you can get on the boat. Every panel will reduce generation run time. Yes I think you are light on panels.

Also, does your boat have a 12v system too? You will need panels and a SCC to charge those up too. (Unless you go with a 48v to 12v converter.) You probably want to delete the lead acid batteries and add a second lithium 12v system. The 12v batteries need a Smartshunt too Or maybe the BMV712 might be better because then there is a screen to look at. I would really suggest going all Victron- but it looks like that ship already sailed, lol.

Do those 12v batteries start anything? Generator/motors? If so maybe keep the lead.

Remember plan out what happens in all the different failures. If someone leaves the A/C on too long and the battery shuts down - how does that impact the boat… etc.

Good Luck

I second keeping lead for heavy 12v DC loads like starting starting the engine and running the bilge pumps (you said pontoons, but you may still have pumps somewhere). You might want a separate panel for that battery as it's likely not to get much of a draw.

Your boat was already designed for 12v for running lights and such, so power runs for that should not be an issue, even if you move those to LFP batteries, especially if you've switched to LED bulbs as you are reducing the amp draw.

I would keep anything that is already 12v, 12v, unless you there is a great improvement in efficiency. You also need to REALLY learn how your isolation works between the batteries, the generator, the solar panels and so on. Messing that up is where I would be most afraid of something going BOOM and letting all the smoke out.

 

[BigMike701]

I second keeping lead for heavy 12v DC loads like starting starting the engine and running the bilge pumps (you said pontoons, but you may still have pumps somewhere). You might want a separate panel for that battery as it's likely not to get much of a draw.

Your boat was already designed for 12v for running lights and such, so power runs for that should not be an issue, even if you move those to LFP batteries, especially if you've switched to LED bulbs as you are reducing the amp draw.

I would keep anything that is already 12v, 12v, unless you there is a great improvement in efficiency. You also need to REALLY learn how your isolation works between the batteries, the generator, the solar panels and so on. Messing that up is where I would be most afraid of something going BOOM and letting all the smoke out.

Hi SparkyGage,

The single outboard (never runs. lol) has a separate 12v starting battery.

The remainder of the 12v system will be isolated with the 48v to 12v 50a converter. All lights have been upgraded to LED and the water pumps (fresh and wash-down) have been replaced to more efficient models. No bilge pumps. And you are correct, it is controlled by a separate 12v fused terminal block for that system.

12v system controls:
(5) 10a 12v sockets (cigarette lighter style),
(15) 12v RV style lights;
(2) On-demand 7gpm, 60psi water pumps;

The 120v system controls:
(10) 15a duplex A/C outlets (2 LR, 1 Bed, 1 bath, 3 Kitchen, 2 Ent Ctr, 1 rooftop patio);
(1) single living room ceiling fan/light;
(3) 75w max ceiling lights throughout the cabin;
All of which was run solely by the generator. The plan is to switch that to the EG4 inverter "A/C Out" side and wiring the generator to the "A/C IN" side of the inverter.

I definitely do not want any "BOOMS" or unintended "smoke" releases, LOL. That's why I went with the EG4 All-In-One system, stepdown converter, battery isolation switch, Class "T" fuse, etc., to keep everything isolated.

I hope this covers all of my bases.

Thanks for your input. I value everyone's expertise here!

Mike

 

[Rocketman]

From my experience of being on a time-share houseboat at Lake Powell and RVing.

The absorption refrigerators work ok in the mid 80’s down to the 40’s. Above mid 80’s they struggle. Above low 90’s they barely work. If it is close to or above 100 - don’t plan on food safe temperatures. (These are all outdoor temps - because of the outdoor ventilation and air & ammonia movement).

You may want to look into a residential refrigerator. They work much better in boating temps and have more room inside. I added about 400w of solar to my RV when I added the residential and it was about right.

Also, you may want to reconsider your 48 to 12v converter. I would add a couple of solar panels (if they fit) and a mppt 12v solar charge controller, and a BMV712 for the 12v system. That way the 12v stuff is completely separate from the 48v stuff. Have a 120v to 12v battery charger so you can charge the 12v system (really both the 48 & 12v systems) when you run the generator (and in an emergency- plug it into the 120v side of the EG4).

But there are lots of ways to design stuff so do what makes sense to you.

Remember KISS - Keep It Simple and Serviceable. You will have to service everything you do in the future- so make it easy on future you. (I am always forgetting that!).

Good Luck