New E21 Boondock Ready(5.1KwH solar system)

[E Ticket]

Hi Bob, Each panel weighs 40lbs. I walked it up with a ladder very carefully putting towels for point of initial contact and using it to slide and position the panels onto the roof. It would have been great if I had help. But I was able to manage. i did the same for my home solar project. One by one slowly up the roof. In that case, I used a hoist I built with 2x4 and a 4 to 1 block and tackle. I did that in the middle of the cool nights so as to avoid the sun.

[Brian B-P]

Originally Posted by E Ticket

- 24VDC (25.6VDC nominal) 200Ah LIfepo4 battery bank

With a nominal cell voltage of 3.2 V for LiFePO4, there must be 8 cells in series. It appears from the first photo that it is an 8s2p (parallel pairs of cells, then series connect eight pairs) set of 100 Ah cells. No wiring is visible, so presumably there are top covers over the terminals and wiring - nice and tidy. Johnny, what's holding the cells in place?

[Brian B-P]

The Victron 24/3000/70 is both an inverter (and transfer switch) and a charger, which is a reasonably common configuration (Xantrex also does this, for instance). Does that mean that the 120 VAC to 12 VDC converter/charger section of the WFCO Power Center is has been removed, or is it still there and used to provide 12 VDC directly (instead of via the Victron inverter/charger and unlisted DC-to-DC converter) when on shore power? I'm assuming, like the others, that this system runs the 12 VDC equipment and thus must include a DC-to-DC converter.

[E Ticket]

Hi Brian, You are correct. That was my mistake in the title of the post. The battery bank is made up of 16, 3.2vdc LifePO4 prismatic cells that are approx. 10"x6"x1.5" wired 8 in series 2 parallel. The entire bank is 5.12kWh. But it's more like 5.3kWh due to warmer temperatures here in California which effects favorably in capacity of the batteries.

[E Ticket]

Hi Brian,

You are very observant. Yes, the Victron inverter/charger is fully capable of charging the battery bank at 70A. It can take 120vac shore power ones it sees and qualifies the incoming AC. The tranfer switch switches the system from DC invert to passing the incoming AC in about 16mS. That's transparent to the load and it sees no interruptions. I have a yamaha 2400W which can be use as a back up to my solar system if the conditions are poor for solar. But I live in SO Cal. Sun energy is not an issue here.

[E Ticket]

Embedded pic

[E Ticket]

Hello rubicon327,

Having no AC on the roof will definitely help laying down more panels. If I did not have the Dometic AC on the roof, I can definitely put another 260w panel up and a few 170w in between. Having a Mini split with significantly more efficiency per watt of energy over the typical roof AC. With the Fujitsu, I am guessing you will consume average of 800 to 1000wh. You will still need a good amount of solar on the roof and on the ground to run the AC and recharge your bank from usage from the night before. I took a trip to the local dessert this past weekend, I harvested 2.4kwh of solar from my 560w on the roof in the October sun. There are no tilt in my panels for simplicity. To answer your question about run time, I designed my system to balance cost and normal usage for maximum ROI. It is all about power management.

[E Ticket]

While we are on the subject of solar, I am a believer in off grid living which I have translated to my "Land Yacht" . Please see my off grid home system. The grid is now my backup on those few rainy California winter days. Please allow me to share these:

5500watt Schneider inverter charger
2x 150V/60A MPPT charger
24kWh LifePO4 battery bank
Com gear
Batrium BMS

Thanks.



https://imgur.com/a/ZZmX1Tl

[E Ticket]

Hi Steve and rubicon327,

Project cost:

5.1kWh battery bank = $2200 including shipping
Victron inverter/charger = <$1300
Victron MPPT Solar charge controller = $159
Victron battery monitor, BMV-712 = $209
260W Hyundai panel = $115 ea. ( I bought a pallet of this 2 years ago at very low price)
Misc wires, breaker switch, crimps... = approx. $300
Elbow grease = $0

The lower cost of this system was due to my approach in buying Lithium cells and wiring it to create the bank. I did not want to spend the money on the Battle born batteries, which are, I believe $989ea

[Brian B-P]

I haven't seen any mention of a battery management system, only the Victron monitor. Is there no BMS? Is charging controlled entirely by the solar charge controller and the inverter/charger, and can their charging profiles be set appropriately for the LiFePO4 cells?

[E Ticket]

Hi Brian,

Both, the Victron MPPT and inverter/charger has well developed LifePO4 charge settings and also user defined settings. They are highly customizable.

For my home off grid system, I have a 24kwWh, 48vdc,16s, 6p bank of LifePO4 that has a BMS. So far, each of the 16 cells are in perfect balance without the BMS having to balance them. They have been up for 2 years working without issues. I have system relays for cutting out the bank when the state of charge(SOC) drops below 20% that trigger switching over to the grid. Same thing on the top end of the SOC. I programmed the MPPT to chargers to charge upto 85 to 93% before switching to float state. The float state just divert the incoming solar to the inverter for loads in the house.

But with that said. A BMS will be in the works. Right now I am the BMS boss.

Thanks

Johnny

[E Ticket]

12V house battery is out. Save another 59lbs or so.

[Brian B-P]

Originally Posted by E Ticket

12V house battery is out. Save another 59lbs or so.

With no 12 volt battery, everything runs from the 26 volt lithium bank... so there's a DC-to-DC converter, right?


Johnny, your post contains an imbedded image link, but nothing shows up... presumably because you have used the web address of the whole imgur page instead of just the image.

Here is the page as a link: https://imgur.com/xYwIw15
... and just the image as a link: https://i.imgur.com/xYwIw15.jpg
and the image, embedded:

[E Ticket]

Hi Brian,

I humbly thank you for attaching the image. I am not very social media savvy. So I had tried to attach at few more images and it's hit and miss. So thank you.

Yes, the 480W, 40A, 24V to 12V, buck converter will supply house voltage to everything. I will try to upload an image.

It make sense to me to do so because it is silly to convert 24V to 120Vac and back to 12V via my 12V charger while boondocking. The conversion lost would be a waste of harvested solar energy. So now I only have a idle lost of 20mA at 24VDC (actually 26.4V or so).

So the forum want an URL for load images. So I google and found Imgur. And just copied the url. Guess that's no good.

Thanks for your interest. I have the new toy syndrome. Haha, I can't stop playing with my trailer.

Thanks,

Johnny

Embedded image - Donna D.

[E Ticket]

Few more thoughts: No more lead acid battery maintenance. I don't have to run the inverter to charge the 12V house battery. And got rite of 50lbs or so.

[Mike Lewis]

Originally Posted by E Ticket

Few more thoughts: No more lead acid battery maintenance.

This is why I switched to lithium batteries at this time. I disliked maintaining lead-acid batteries in the cramped confines of the trailer. And since I disliked the task I postponed it, thus shortening the life of my original batteries. Now I won't have to deal with it anymore.

[Karl@Escape]

Looks great Johnny.

[E Ticket]

Hi Karl,

Thank you. I love my 21. Hope all is well in Chilliwack and that you are out riding and enjoying the North American life style.

Johnny

[Defenestrator]

Nice setup!

You'll want to keep an eye out for heat buildup in the compartment with the Multiplus, especially when you're taking advantage of the hybrid converter mode. That's a fair bit less room to either side than Victron suggests and there's some risk of things getting a bit melty. A passive vent or even some sort of temperature-controlled 12V fan might be a good idea.

[E Ticket]

Hi Defenestrator,

You have a valid concern and I agree that I need better thermal management regarding my setup. To mitigate this, I removed the inverter top cover to allow more free air flow when the system fan activates.

Will most likely add a fan for the summer months.