Planning My Lithium Power System - Looking for Feedback

[SVBLU]

I've been trying to learn as much as possible regarding the installation of my new lithium power system. I'm picking a lot of it up, but a lot of it is going over my head. Here's where I'm at:

Energy Spreadsheet:
After completing my energy spreadsheet I estimate around 300ah at anchor. I plan in installing 700ah worth of lithium batteries.

Batteries:
7 LiTime 100ah Lithium Batteries. The reviews for these are good and they have really good pricing when you buy them in 3 or 4 packs. Open to your feedback. I have measured out a space in my storage cabin that is along the centreline and they should fit.
https://www.litime.com/products/liti...rolling-motors

Solar Panels:
I've decided on the following panels after double checking my measurements and space availability.
2 x Renogy Bifacial 220w installed on my arch (https://www.renogy.com/bifacial-220-...e-solar-panel/)
1 x Xantrex Flexible 330w installed on my dodger (https://xantrex.com/products/solar-p...lar-max-panel/)

MPPTs:
I have a small amount of shading that will occur on the 2 panels that are on my arch from my radar and starlink. Very small amount. I have been told that I should get separate controllers for each panel on the arch to deal with the shading. One more for the Xantrex solar panel. So I'm thinking three total. Am I correct that the Victron MPPT 75/15 will be compatible? (https://www.victronenergy.com/solar-...-100-15-100-20)

Inverter:
Current one on my boat is a Xantrex Prosine 1000W inverter. Is this compatible ? Should I keep or upgrade to a Charger/Inverter combo?

Battery Charger:
Not sure which one to go with based on my system. I'll need advice on this. I read that I should be good with a Victron smart charger but not sure on this one. (https://www.victronenergy.com/charge...t-ip43-charger). Or do I go with the Charger/Inverter?

Bus Bar:
I'm updating to a Victron busbar or an equivalent.

Alternator and Starter Battery:
I plan to keep my current lead acid starter battery. I've seen that many sailors are doing a set up with the Alternator > Starter Battery > DC/DC Charger > Bus Bar. I'm not sure if I should keep my Victron Energy 12 volt 30amp Centaur battery charger for the starter battery?

I'm attaching a very amateur schematic that I created in an attempt to understand what I'm doing. I know this is a lot of information but I thought it would be best to put it out there and get some feedback.

Cheers,
SVBLU

[noelex 77]

Welcome to the forum.

Generating 300 Ahrs from 770w predominantly from solar demands very good solar insolation. What areas and seasons are you planning to cruise?

[SVBLU]

Originally Posted by noelex 77

Welcome to the forum.

Generating 300 Ahrs from 770w predominantly from solar demands very good solar insolation. What areas and seasons are you planning to cruise?

Thanks for the welcome! I'm a 365 live aboard. Spend most of my time in the Bahamas and Caribbean. Currently in the Chesapeake doing some work on the boat.

[noelex 77]

Originally Posted by SVBLU

Thanks for the welcome! I'm a 365 live aboard. Spend most of my time in the Bahamas and Caribbean. Currently in the Chesapeake doing some work on the boat.

These areas have excellent solar insolation all year round. 300Ahrs from 770W of solar is achievable, although you will need relatively unshaded panels.

Keep in mind that if you venture to areas with moderate solar insolation your electrical system will need a rethink.

[sailingharry]

75/15 MPPT max out at about 200W. More than that doesn't hurt them, just wastes power. Ok-ish on 220W panels, serious waste on 330W panel.

How big is your alternator and how is it regulated? I suspect it was a bigger part of your power solution in the past. Throttling it to 30A sounds painful. My 270A of alternators put out 170-200A all day long, but you may have much less. If you have a decent temperature compensated regulator (Balmar, etc), consider getting more power from it. Drop -ins make that a challenge.

[Pete7]

Edit, to merge two identical threads.

That all looks quite sensible, though your daily usage is 3.6kWh and those solar panels won't generate all the power you need. To get a better idea of what they could generate each month of the year, this website is reasonably accurate:

https://en.sunware.solar/systemsize/daily_yield#tabelle

We have the same issue outside of the peak summer months and also use the alternator to top up occasionally.

The new Renogy bifacial panels look interesting and fill a neat gap after LG pulled out of the solar panel market leaving a void in the range of bifacial panels. I am assuming this is quite a big yacht, any space to add a third 220w Renogy panel on the arch? Our two arch panels total 590w and we see 2kWh peak summer at 50'North, you should generate more further south.

I would keep the Victron centaur mains battery charger which can be used if you need and shore power is available to the engine start battery and from there to the LFP batteries via the DC>DC charger. In use we see about 25-27A from the Victron 30A model. Just be aware they get hotter than the sun even mounted in a free space. So do not mount it under a berth or in a cabinet without ventilation. Ideally put a small computer fan behind it to assist cooling. This is the temperature of our Victron DC>DC charger after an hour. It's mounted on the outside of the nav seat with a 3" hole behind it. I plan on fitting a PC fan this winter.

The PSW Xantrex inverter will be fine. Consider adding a GFGI (RCD/RCBO) to the output for safety. If in the future you need a larger one, keep the Xantrex as a spare.

[Pete7]

Out of curiosity, what are you running that is using 3.6kWh each day?

Pete

[sailingharry]

Originally Posted by Pete7

Out of curiosity, what are you running that is using 3.6kWh each day?



Pete

It's a lot, but not out of the realm of possibility. 3.6 kWh is about 300Ah.
* My fridge was running nearly 24/7, at 5A. I've made adjustments and it is now running about half that much, but that was 120 Ah
* My Chart plotters consume 5A. About 10-year-old Furuno units that don't allow one of the pair to be turned off. On longer passages away from shore, I will sometimes turn the whole unit off and use a phone. But if left on, another 120 Ah.
* An inverter on standby can be close to 5A. If you like to have it on full time, another 120A.
* We like to use an electric drip coffee maker and toaster every morning. Easily 30Ah.

We don't use all that consumption all day everyday. We definitely manage down below that. But just those numbers can explain a 3.6 kWh day.

[GreenWave]

I would get one Victron Smart Solar 100/30 for the two rigid panels and then a separate 75/15 for the flexible. Wire the rigid ones in parallel.


Rest of your plan seems reasonable though I like a combined inverter/charger approach personally.

[SVBLU]

Originally Posted by Pete7

Out of curiosity, what are you running that is using 3.6kWh each day?

Pete

Two of us living and working full time on the boat requires a good amount of energy. Some of our larger consumers (daily):

Fridge: 72ah
Starlink: 52ah
Interior fans: 40ah (no air conditioner)
Laptop Chargers: 22ah
Interior lights: 22ah

[sailingharry]

Originally Posted by GreenWave

I would get one Victron Smart Solar 100/30 for the two rigid panels and then a separate 75/15 for the flexible. Wire the rigid ones in parallel.


Rest of your plan seems reasonable though I like a combined inverter/charger approach personally.

Respectfully, I disagree.


The 75/15 is about half the price of a 100/30 -- so two of the smaller for the same price as the larger. If you have the wiring (or can easily add it) and the space for the controllers, the two 75/15 are a better choice. You still leave 10% of available power behind at peak sun (which you would with the 100/30 as well). To get full use of the panel sizer, you'd need two 100/30's or a 100/50. Neither are worth the extra investment, IMHO. I'm in a similar predicament with 2 400W bifacials -- do I use 2 100/30's and leave a bit behind, or spend another $100 per controller for 2 100/50's and gain 10% at peak (but no penalty the rest of the day).



The flexible all but requires a 100/30. Using a 75/15 leaves nearly half your full power behind, and a significant amount for much of the day. The 75/15 is only good for 200W at 13V. The 100/30 is good for nearly 400W, a perfect fit for the 330W flexible.

[Pete7]

Originally Posted by sailingharry

I'm in a similar predicament with 2 400W bifacials -- do I use 2 100/30's and leave a bit behind, or spend another $100 per controller for 2 100/50's and gain 10% at peak (but no penalty the rest of the day).

I am willing to bet that you probably couldn't use that 10% when it occasionally occurs anyway. The time you need every drop is when its cloudy and end of season. This is when having a MPPT for each panel really helps.

We have a 100/50 controlling 2 x 295w panels in parallel. We also have a spare 100/20 from the previous smaller installation, so may yet go down the single panel to MPPT route. However, I am playing around with a 110w very narrow rigid panel for the guard rails at the moment, as a portable panel. Oh and Renogy have just brought out a 220w bifacial panel at quite a good price, hmm.

Oh, we use 10A under sail for the plotters, VHF, AP etc.

Pete

[sailingharry]

Originally Posted by Pete7

I am willing to bet that you probably couldn't use that 10% when it occasionally occurs anyway. The time you need every drop is when its cloudy and end of season. This is when having a MPPT for each panel really helps.

Agreed. Which is why I said it wasn't worth it. Two 75/15 are the right answer for his 220W, and I think 2 100/30's for my two 400W are my right answer.

[hlev00]

Check out Rod's excellent articles on LFP if you have not already. Here is one : https://marinehowto.com/lifepo4-batteries-on-boats/

On the batteries you should verify with the manufacturer that they can be paralleled and if so how many can be. I suspect they will supply the maximum current required to support your inverter. If you think you will go to a higher capacity inverter then check that they would meet that.

Charging the house bank via a DC-DC charger is okay but it is slow and you lose efficiency. Though moving the alternator to charge directly takes protection of the alternator in case of all BMS disconnecting and also a sufficient alternator with external regulator being configured to handle the continuous charging the house bank could demand. If you are just using a stock automotive alternator then your current design is all you can do in that regard.

You don't show any fuses on the batteries. What are you planning for that?

Disconnect switches for the panels. I think likely fusing for the MPPT to Lynx distributor but check both manuals to be sure.

[Pete7]

Originally Posted by hlev00

On the batteries you should verify with the manufacturer that they can be paralleled and if so how many can be.

Good Point

Originally Posted by hlev00

Charging the house bank via a DC-DC charger is okay but it is slow and you lose efficiency.

True, but a very safe option. Indeed my Sterling LFPs require a DC>DC rather than direct alternator to LFP connection, probably because they don't trust customers to not make a mess of it.

Originally Posted by hlev00

You don't show any fuses on the batteries. What are you planning for that?

That will be those Class T fuses.

Originally Posted by hlev00

Disconnect switches for the panels. I think likely fusing for the MPPT to Lynx distributor but check both manuals to be sure.

The Lynx has fuses inside to join the positive connections to the bus bar. I have the cheaper Power In, which with 4 bolts can and has been converted to take fuses like the Lynx.

Pete