48 VOLT SOLAR LITHIUM SYSTEM

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48 VOLT SOLAR LITHIUM SYSTEM

December 21, 2016, 08:53:00 am

In designing the next generation solar / lithium electrical system for my 1997 U270, I have the following questions:

1. 220VAC WIRING
How does Foretravel split the 50Amp 220V shore power? The schematics do not show it being split throughout the house electrical system. The generator is 120VAC. What is the use of extra 120VAC leg of the 220VAC shore power?

2. 48VDC BATTERIES
Any reason why a 48VDC to 12VDC converter wouldn't work to power house loads like the referigerator, heaters and lights?

3. TAX REFUND
Any reason why I couldn't take the 30% tax refund for purchasing 1200Watts of solar panels, 7KWH of lithium batteries, 48V solar MPPT charger, 48VDC to 12VDC converter and all associated wire, breakers and relays?

4. MOTIVATION
Am I crazy because this is a lot of work that I will do myself? Will it make the coach worth more? Will it save money in the long-run over lead batteries? Being an electrical engineer, I look for ways to improve our boondocking capability and reduce annoying generator noise. Some campgrounds in Big Bend National Park prohibit all generators.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #1 – December 21, 2016, 09:06:01 am

The electrical stuff is over my head, but this post (link below) may help you answer your question on the tax credit:

RV Solar Tax Credit (update)

The way it was explained to me, you can include any costs associated with making your residence (coach) ready to accept the solar installation. For instance, if a person was installing solar panels on the roof of a house, and the roof had to be "strengthened" to accept the added weight of the panels, then the cost of the roof reconstruction work could be included in the amount claimed on the credit.

I am not a tax attorney. If you have any questions about what can or cannot be claimed, I recommend consulting a tax expert.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #2 – December 21, 2016, 09:15:29 am

Quote from: Tim – December 21, 2016, 08:53:00 am

1. 220VAC WIRING
How does Foretravel split the 50Amp 220V shore power? The schematics do not show it being split throughout the house electrical system.

It should. There should be a page showing the main breaker box with Leg 1 and Leg 2.

Quote from: Chuck & Jeannie – December 21, 2016, 09:06:01 am

I am not a tax attorney. If you have any questions about what can or cannot be claimed, I recommend consulting a tax expert.

^^^ What Chuck said. Your accountant/tax person is the only one who can accurately answer this for your situation.

^^^

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #3 – December 21, 2016, 10:47:35 am

I thought the generator was 220 volt. Do different coaches have different configurations?

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #4 – December 21, 2016, 10:55:05 am

I believe all coaches are 220 volt output, but do not have a dedicated 220 circuit, only using both 120 to neutral legs. You will also need a dedicated 48 vdc to 120 vac inverter to run your regular 110v loads.
It may make your coach worth more, but only expect about a 10% return on any
upgrades you put in your coach if you sell it.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #5 – December 21, 2016, 11:02:53 am

The data plate on my Isuzu IDL 8000 generator says "115VAC" period. In a way, that makes it simple, but I guess Foretravel decided that if you are only plugged into 30Amp 115VAC shore power, you had better be able to run the whole rig. The question remains: what is done with the other 115VAC leg?

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #6 – December 21, 2016, 11:08:50 am

I was told both legsare connected together at the generator. My Power Tech is a 120 volt generator. There are special instruction available to convert it to 220 volt output ...though you better know what you are doing to be sucessful.

Jim

2002 U320

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #7 – December 21, 2016, 11:14:10 am

Generator Diagram to change 110vac to 240vac

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #8 – December 21, 2016, 11:37:55 am

While I'm no expert on generators, I believe both 110 volt legs go to the panel(s) powering one side of each bus therefore just like your home electric. It helps keep the load balanced. You can as I understand it make some minor changes in the generator to make I a true 220.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #9 – December 21, 2016, 11:42:04 am

Tim,

Don't know if it will make the coach worth more. I put 1140 watts on the roof for the same reason, to get rid of the generator noise. I have not used the generator in years. I hate the noise, smell and vibration. At any kind of altitude, the generator really smells. Many National Parks mix tents with RV. I have had furious tent residents pound on my door to shut it off. Many NP visitors come from Europe where they don't use generators on RVs so don't understand why we allow them.

Don't think it's practical to expect 1200 watts on the roof to provide enough power for the heating, cooking, etc. When do you need heat the most? In winter with low sun angles. Plus, they won't run AC units if you dry camp in summer. You are not going to get anywhere near 1200 watts in a real world especially in winter. You would have to tilt the panels and I consider that too risky unless you motorized them. Parking in full sun is also iffy in many places. Stormy weather cuts the watts down, way down. Propane for heating, cooking and the fridge is a good compromise. Our 36' U300 with the walk though bath is one of the only Foretravels where you can mount four very large 300 watt panels without a conflict with AC, vents, etc. Otherwise, you have to utilize more smaller panels to get the same output. Makes it far more complex to tilt.

The roof or structure will not need reinforcement no matter how many panels you put up there.

With our panels, we bring about 70 volts down to a Midnite Classic 150 MPPT controller and then into 6 solar AGMs. They work great after almost 8 years for 40" TV, computer, lighting, latte maker, etc. At Quartzsite, in the dead of winter, we get about 600 watts. Enough to bring the batteries up by 10:30. I did it all myself after spending a lot of hours coming up to speed on all the dozens of little details. Commercial companies will never be able to match what a well informed RV owner can do. Looking around, I was able to get the highest quality possible components for less than $2000 plus the batteries. I got an unusual deal on the batteries so didn't include them in the cost. They came out of the back of a truck but they didn't fall out.

We just got back from a coast to coast and back trip. We mixed campgrounds with parking lots and in a month, never even thought about the generator. The trip in summer would mean either more campgrounds with power or generator use. In Mexico, we usually stay in campgrounds as they are located overlooking the ocean, have reasonable rates plus our stays are longer. It's nice to have the septic, water, hot clubhouse showers plus power for the ACs. The vendors with the fresh shrimp, tamales are an added perk.:-)

And yes, I took the tax deduction.

Pierce

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #10 – December 21, 2016, 12:18:14 pm

Tim-
As an electrical engineer you know that it is almost impossible to make it perfect, but sounds like you are on to something you enjoy.

We live in our 2001 U270 full time and just this past January I had installed a simple solar system to reduce my generator use. The system has exceeded my original expectations and I am very pleased with the results.

I have 2 roof mounted 250 Watt, high efficiency 24 volt panels, running down to the MPPT controller which converts the voltage to 12 volts, then to my 2 8G8D batteries. This system works very well and I have the option but choose not to climb up and tilt the panels. We use propane for heat, cooking, refrigerator and a smaller inverter to charge cell phones, laptops, etc. I only turn on the big 3000 Watt inverter when we need it or want it to power tv, etc. We can go a long time without ever running the generator, unless we are going to do baking or something like that. In the spring time, we have gone 2.5 weeks strictly on solar.

I had my system installed out in Slab City in the desert of CA by Solar Mike for $1200. Happy with the price, happy with the work, happy with the results.

Figure out how you want to use your system and design it based on your usage. I don't expect this to be an investment for anyone but us as we plan on living in this coach another 10 plus years.

Keep us informed about your project. I am interested in how the Lithium batteries will work long term.

Merry Christmas

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #11 – December 21, 2016, 12:33:43 pm

Hey Ted, just had Mike at Slab City put 850 watts on the roof, works great.

X 2 on what Pierce said.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #12 – December 21, 2016, 12:40:14 pm

Tim I will post some answers to your questions shortly. We have the same coach and I just added 900w solar, 3000 Multi inverter, 400 ah lithium, and CCGX panel. I went all Victron and glad I did. There were several work arounds required and my best guess is I am somewhere around 150 hours into the project, not counting the first month and a half learning electricity, and buttoning up today and tomorrow. I did not have previous electrical experience as you do but learned on the job and climbed and confessed to AM Solar when I got lost. I was their first DIY coach of this type. Made for a great learning experience for both parties and they have changed a number of things based on that learning curve.

My first home remodeling effort was the kitchen to the studs and this was a similar journey. My immortal beloved was a little less patient with that one.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #13 – December 21, 2016, 02:43:26 pm

Hey Bruce- glad it worked out for you. Mike knows his solar and is a unique person- a pleasure doing business with him.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #14 – December 21, 2016, 07:59:18 pm

Bruce, was the price at slab city a better price than AM solar would do?

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #15 – December 21, 2016, 09:16:43 pm

I plan on:

- Three 320W solar panels from eBay
- 7KWH of Lithium. That's 16 130AH LIFEPO4 batteries running at 48 volts
- 48 volt solar MPPT charger
- 48 volt to 120VAC pure sine wave inverter / charger
- 48 volt to 12VDC charger.
- The 12VDC house voltage may come from a small 30AH LIFEPO4 pack, which will be maintained by the 48V main pack.

Just have to figure out how to handle the genny and shore power. Big job.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #16 – December 21, 2016, 09:20:57 pm

Where are you getting the lifepo4 at? And how much ? Are you buying as a kit or assembled ?

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #17 – December 21, 2016, 09:33:31 pm

Quote from: Tim – December 21, 2016, 09:16:43 pm

I plan on:

- Three 320W solar panels from eBay
- 7KWH of Lithium. That's 16 130AH LIFEPO4 batteries running at 48 volts
- 48 volt solar MPPT charger
- 48 volt to 120VAC pure sine wave inverter / charger
- 48 volt to 12VDC charger.
- The 12VDC house voltage may come from a small 30AH LIFEPO4 pack, which will be maintained by the 48V main pack.

Just have to figure out how to handle the genny and shore power. Big job.

Do not skimp on the solar, general rule 1 watt solar to 1 ah battery. Will over 2000 ah's go big.
A couple of cloudy days will deplete even 2000 ah's if you are running enough equipment. A good mppt controller will charge as fast as the batteries will take it and then shut off, so no such thing as too much solar.
I had a foretravel with 1200 watts solar and 900 ah batteries, and there were times when I wished for more solar.
If you leave an inch or so between panels and roof, heat transfer will not be a problem.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #18 – December 21, 2016, 09:33:49 pm

Rbark yes way less expensive than AM solar. 2300.00 tax inc with an outback Flex max 80 mppt controller.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #19 – December 21, 2016, 10:03:28 pm

Quote from: Tim – December 21, 2016, 09:16:43 pm

Just have to figure out how to handle the genny and shore power. Big job.

Tim,
These are for my '96 295.
The first one "110v ELECT RELAY SYSTEM" (A-2700.07), shows two 110v hot legs
coming to Transfer switch #1 from either the Shore Power line or the Generator.
Sheet 1 of 2, A-2700.03 shows what circuits (in my nominal coach) are assigned to which legs.

Note that either the inverter output or leg 2 from shore/gen feed the circuits delineated on A-2700-3 page 2/2).
HTH

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #20 – December 22, 2016, 10:36:07 pm

Thanks for the diagrams. Do you have a diagram for SWITCHING RELAY #1?

This switching relay must have the "intelligence" for two states:

1. 220VAC SHORE POWER (50AMP)
Connect each of the two 110VAC legs to the MAIN CIRCUIT BREAKER BOX, Circuit #5 and 7

2. 120VAC SHORE POWER (30AMP) or GENERATOR POWER
Connect the single 120VAC leg to both legs of the MAIN CIRCUIT BREAKER BOX, Circuit #5 and 7

What happens if the genny is running and shore power are connected at the same time? Smoke?

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #21 – December 22, 2016, 10:54:55 pm

Can anyone who has installed solar on their coach describe how they ran the cables from the roof to the basement?
I want to install solar on my U320.

Ken

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #22 – December 22, 2016, 11:08:28 pm

Quote from: KenKetch – December 22, 2016, 10:54:55 pm

Can anyone who has installed solar on their coach describe how they ran the cables from the roof to the basement?
I want to install solar on my U320.

I ran them down the fridge vent, down the corner of the fridge compartment, then through the floor of the fridge compartment, then down through the ceiling of the basement bay, then across the ceiling of the center of the basement bay, along the large wire run (under a fiberglass ceiling panel) and into the battery bay.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #23 – December 22, 2016, 11:09:40 pm

Ken down through the vent for the fridge, behind the false back in the cabinet below the fridge.

Re: 48 VOLT SOLAR LITHIUM SYSTEM

Reply #24 – December 22, 2016, 11:10:22 pm

Quote from: KenKetch – December 22, 2016, 10:54:55 pm

Can anyone who has installed solar on their coach describe how they ran the cables from the roof to the basement?
I want to install solar on my U320.

Ken

Through the fridge vent on the roof, then drill on bottom of rear fridge compartment into the compartment below fridge, then to basement compartment and fwd to where your controller is.

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