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Old 08-02-2023, 06:22 PM   #1
Mini-Skoolie
 
Join Date: May 2020
Location: Maine
Posts: 40
Year: 09
Engine: 7.6 Int DT466
Is this Solar Overkill???

Hello All!

I will be picking up my bus in a week or two. I'll be sure to start a build thread once things are underway. In the meantime, I would like some input on what I have "estimated" for my solar usage, aka is this overkill???

I'd like to run a 48v system. 2 LifePo4 Lithium Batteries. 230AH each for 48v 460AH= a hair over 22kWHs. 10-390W panels configured 5s2p so long as my roof hatch plans don't interfere.

It is more of a dream to run AC on solar so I could limit it or run AC solely shore power. I plan to full-time in the bus and would like to be able to boondock for up to 2-3weeks at a time. Bring on the calculations.

AC Systems Volts Amps Watts Hours Watt Hours

A/C 115 9.3 990 10 10000
Fridge 120 1.3/4.5 140 24 3360
Vent Fan 120 .125 15 24 360
Stove (LP) 120 5 600 2 1200
Microwave 120 9.4 1040 0.2 208
H2O Heater(LP) 120 .35/20 42 2 84
TV 120 1 120 5 600
Laptop 110 1.8 65 12 780
Box Fan 120 1 75 6 450
LED Lights 120/24 5 120 8 1200***

DC System

8kw Heater 12 1/10.5 7-35 24 840
5kw Heater 12 1/10.5 7-35 24 840
Tank Sensor 12 200mA 2.4 24 60
H2O Pump 12 7.5-10 90 2 180
Phone x2 5 1.8 10 8 144

90.525 3400 9110***(10k)
(20k w/ AC)
Inverter I'm looking at Renogy 3500W all-in-one or a 5kw all-in-one posted here:

https://www.amazon.com/Inverter-Char...63b24bcb5&th=1

I'd also have an additional 5kw inverter for while underway.

48-12v Converter

The lights I found a 120v 48w system but I'm looking into 48v LED RGBW strip lights to reduce loses going from DC-AC-DC.

Also some things I overestimated and some I may have underestimated. I tried to keep the underestimation minimal and overestimation rounded up.

Thoughts?

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Old 08-03-2023, 02:52 AM   #2
Skoolie
 
Join Date: Aug 2022
Location: Lost
Posts: 104
Year: 2002
Coachwork: Bluebird
Chassis: All American
Engine: 8.3 Cummins
I won't say a ton because I bought them but haven't put them into service yet however, my friend uses MPP Solar at his place as well and has been happy with them. He runs 2 of the 6,500 watt units, I have 4 of the 3,500 watt units for my build. My concerns are always redundancy and with 4 units I'm pretty set and it works well with the solar.

I deal with Linda Haung here:

https://mppsolar.en.alibaba.com/

Great pricing and always to my door within 7 days.

I have 12 panels for 5,000 watts on my roof and then I'm mounting another 1,000 watts down each side of the bus along with another 2,000 on my trailer I'm pulling behind me. So in total I'll have around 9,000 watts of solar.

I always try to reduce use first but I'll have AC, washer/dryer, tankless electric water heater, induction cooktop and so on. I NEVER use propane for anything, why, solar is cheap, batteries are getting there and you don't have to refill it.

Somebody else will chime in I'm sure.

Oh and I have 3x120ah 48v batteries, I maybe buy more, 2x280ah instead but I don't know for sure yet.
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Old 08-03-2023, 03:25 AM   #3
Bus Crazy
 
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Join Date: Jun 2020
Location: Long Beach, CA
Posts: 1,075
Year: 1998
Coachwork: Blue Bird
Chassis: TC2000, 40' MPV
Engine: 5.9 Cummins/B300 trans
Rated Cap: U/K
I have two MPP 24v 2400 watt combo units, they can be paralleled for 240v output. They seem to be really well put together. I opened one up to take a peek. The only thing they lack is a remote start option (at least on mine). My plans are to have two separate 24v DC systems, one for lights, sound and misc. and the other for a DC refer and separate freezer. I plan on using propane for the water heater and cooking. Overall, I don't have too much planned for AC electric.
It sounds like you're on the right track but you might want to consider a couple more batteries, there will be crappy days when all those panels will have low to zero output.
...and a generator
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Old 08-03-2023, 10:44 AM   #4
Bus Crazy
 
Join Date: Apr 2020
Location: Northern California (Sacramento)
Posts: 1,429
Year: 1999
Coachwork: El Dorado Fiberglass
Chassis: Ford E450
Engine: V10 Gas
Quote:
Originally Posted by N5tavniec View Post
Hello All!

I will be picking up my bus in a week or two. I'll be sure to start a build thread once things are underway. In the meantime, I would like some input on what I have "estimated" for my solar usage, aka is this overkill???

I'd like to run a 48v system. 2 LifePo4 Lithium Batteries. 230AH each for 48v 460AH= a hair over 22kWHs. 10-390W panels configured 5s2p so long as my roof hatch plans don't interfere.
Back of napkin calculations:
Wintertime use
I think you need about 485 AH storage and 11.6K solar for comfortable wintertime use. You have 344 AH storage capacity (assuming you keep the charge between 10% and 90%) and can produce about 11K watts solar daily, so you're pretty close on solar, probably okay, but a bit short on battery storage.

Summertime use
You'll need 750 AH storage for comfortable summertime use, in my estimation, and way more solar, closer to 30K watts to cover that AC.

This is based on your demands (I estimate about 24K watts in summer and 11K watts in the winter), average daily hours of sun in Maine (5 in summer, 3.5 in winter), and the assumption you need 1.5x your demand in battery storage in summer and 2x demand in battery storage for winter, allowing for cloudy days).

If you skip trying to run the AC on batteries the current system looks pretty good.

Other things I factor in:
--Solar panels operate at no more than 80% efficiency from their rated wattage, more or less.
-again, this is back of the napkin.
Quote:

It is more of a dream to run AC on solar so I could limit it or run AC solely shore power. I plan to full-time in the bus and would like to be able to boondock for up to 2-3weeks at a time. Bring on the calculations.

AC Systems Volts Amps Watts Hours Watt Hours

A/C 115 9.3 990 10 10000
Fridge 120 1.3/4.5 140 24 3360
Vent Fan 120 .125 15 24 360
Stove (LP) 120 5 600 2 1200
Microwave 120 9.4 1040 0.2 208
H2O Heater(LP) 120 .35/20 42 2 84
TV 120 1 120 5 600
Laptop 110 1.8 65 12 780
Box Fan 120 1 75 6 450
LED Lights 120/24 5 120 8 1200***

DC System

8kw Heater 12 1/10.5 7-35 24 840
5kw Heater 12 1/10.5 7-35 24 840
Tank Sensor 12 200mA 2.4 24 60
H2O Pump 12 7.5-10 90 2 180
Phone x2 5 1.8 10 8 144

90.525 3400 9110***(10k)
(20k w/ AC)
I'll just note that these demand estimates look reasonable, and when calculating battery and solar panels assume you won't run both the diesel heaters and AC at the same time, so the max load calcs are usually going to be based on summertime cooling needs and available insolation (sunlight)
Quote:

Inverter I'm looking at Renogy 3500W all-in-one or a 5kw all-in-one posted here:

https://www.amazon.com/Inverter-Char...63b24bcb5&th=1

I'd also have an additional 5kw inverter for while underway.

48-12v Converter

The lights I found a 120v 48w system but I'm looking into 48v LED RGBW strip lights to reduce loses going from DC-AC-DC.

Also some things I overestimated and some I may have underestimated. I tried to keep the underestimation minimal and overestimation rounded up.

Thoughts?
Not sure if just throwing numbers out there without showing calculations is helpful to you.
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Old 08-03-2023, 11:14 AM   #5
Mini-Skoolie
 
Join Date: May 2020
Location: Maine
Posts: 40
Year: 09
Engine: 7.6 Int DT466
Thanks for the input. I get my battery bank is currently undersized. This is what I'm looking to start with and increase as I go. I could boost it to 280AH cells for 560AH to start if i need to. Things are still being tweaked, and will be until....forever, I guess.

I don't really want to run propane but am trying to take a load off the solar hence the LP stove and water heater (looking at electric options for both). I'd like to stay away from a generator for now. I can always add one later.

This gives me an idea of where I'm at so I can go back and change things or see where I can increase efficiency.

As far as inverters go, I'm headed towards a 5kw+ inverter and possibly doubling up to run in parallel (after an upgraded battery bank of course).
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Old 08-09-2023, 04:24 PM   #6
Mini-Skoolie
 
Join Date: Jul 2023
Location: Southeast Louisiana
Posts: 49
I’d recommend watching the solar videos by Chuck Cassady on YouTube. He also offers design services and sells the systems and will provide you all the schematics for installation. He’s been doing this for years.
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