stupid inverter question, 2220 watts of solar on roof

[rockwind1]

i have 6 375 watt panels i am putting on my rv roof (these panels are not as efficient as the newer ones) and i have 2-300ah 12volt epoch batteries. i have 3-Victron Energy SmartSolar MPPT 100V 50 amp 12/24-Volt Solar Charge Controller (Bluetooth)
using 1 each for every 2 panels. (my friend who is helping me install suggested doing it this way)

anyway,, i have the inverter for a 4 gallon bosch 120v water heater and maybe the microwave.
My current inverter is an older xantrax 1.8k I think. See pic

is it stupid to buy an inverter capable of running a smaller 8k midea AC unit that pulls around 750 watts? or even my main ac which pulls around 1150?

this is going on my fifth wheel. any suggestions for an inverter?

i was also going to be putting my refridge on electric and i have the usual led lights in the trailer. don't have a tv or much else.

 

[sunshine_eggo]

The PV arrangement sounds fine. I would just be concerned that you don't exceed 100V. 2S 72 cell panels can > 100V in cold weather.

You haven't listed your existing inverter.

You haven't specified your system votlage.

Most inverters hit peak efficiency at about 30% max continuous output rating.

 

[rockwind1]

The PV arrangement sounds fine. I would just be concerned that you don't exceed 100V. 2S 72 cell panels can > 100V in cold weather.

You haven't listed your existing inverter.

You haven't specified your system votlage.

Most inverters hit peak efficiency at about 30% max continuous output rating.

hi, thanks

older xantrex 1.8watt.

my rv system is 12 volt

i will post pic of my solar panels

 

[sunshine_eggo]

Okay, you you're WAY over-paneled. A 100/50 can only output 50A.

You have 6*375W = 2250W

Most you're getting out of a 100/50 @ 12V is 700W @ peak battery voltage.

You're within the limits of the 100/50 for over-paneling (60A input max), and 41Voc is fine. Just want to make sure you're aware that you're a long way from getting your array's max power out, but you'll get 700W out of it for as long as a 2250W array will output 700W.

Given that your inverter is modified sine wave, I think you should replace it on that basis alone and upgrade to an inverter/charger that better meets your needs.

 

[rockwind1]

Okay, you you're WAY over-paneled. A 100/50 can only output 50A.

You have 6*375W = 2250W

Most you're getting out of a 100/50 @ 12V is 700W @ peak battery voltage.

You're within the limits of the 100/50 for over-paneling (60A input max), and 41Voc is fine. Just want to make sure you're aware that you're a long way from getting your array's max power out, but you'll get 700W out of it for as long as a 2250W array will output 700W.

Given that your inverter is modified sine wave, I think you should replace it on that basis alone and upgrade to an inverter/charger that better meets your needs.

Inverter recommendations?
I just wanna make sure you know I have three of the 100/50 controllers, so I’ll have two panels going into each controller

 

[sunshine_eggo]

Inverter recommendations?
I just wanna make sure you know I have three of the 100/50 controllers, so I’ll have two panels going into each controller

LOL.. indeed... I see that now. Sorry. You're covered then.

Whelp, it should be no surprise that I would recommend a Victron MP or MP-II 12/3kVA. That should cover all of the existing loads, and allow you to run two of the big loads at once with lots of surge margin. The rooftop AC might need a soft start. The MP-II has an absurdly low idle consumption of 13W. At 3kVA, your big loads would be in the 25-50% range in the high efficiency range.

Then you'll want a cerbo to integrate the MPPT and inverter...

 

[rockwind1]

of course I will want a cerbo,,, fur sure! just need to figure out what a cerbo is,,, more google research. i do have a soft start on my bedroom 13btu ac, but the brand new tosot rv ac i bought i think has a built in soft start. i still have the old microair soft start unit though that i took of my old one.

 

[sunshine_eggo]

of course I will want a cerbo,,, fur sure! just need to figure out what a cerbo is,,, more google research.

Cerbo GX is a control center for Victron systems.

i do have a soft start on my bedroom 13btu ac, but the brand new tosot rv ac i bought i think has a built in soft start. i still have the old microair soft start unit though that i took of my old one.

Mini-splits are "inverter-type" with variable speed compressors and no surge.

 

[chrisski]

is it stupid to buy an inverter capable of running a smaller 8k midea AC unit that pulls around 750 watts? or even my main ac which pulls around 1150?

Staying in the Victron product line is nice.

I have all Victron except for the inverter. I have a SAMLEX PST 24 volt 3000 watt and I can run a single AC that has an easy start. The 12 volt should work for you.

Those ACs you list seem pretty small for a fifth wheel. I need a 15 k BTU for the main cabin which pulls 1470 watts from the inverter and 1700 watts from the batteries and I think the master bedroom is 13.5 k BTU. I consider my ACs slightly undersized for a fifth wheel.

I measured a friends AC ran around 1150 watts in a small basecamp Airstream and that was good.

 

[rockwind1]

Staying in the Victron product line is nice.

I have all Victron except for the inverter. I have a SAMLEX PST 24 volt 3000 watt and I can run a single AC that has an easy start. The 12 volt should work for you.

Those ACs you list seem pretty small for a fifth wheel. I need a 15 k BTU for the main cabin which pulls 1470 watts from the inverter and 1700 watts from the batteries and I think the master bedroom is 13.5 k BTU. I consider my ACs slightly undersized for a fifth wheel.

I measured a friends AC ran around 1150 watts in a small basecamp Airstream and that was good.

May I ask why you did not go for the Victron inverter? Was it cost or something else? I wish they made like a 3500 W inverter.

I actually have the same set up, a 15 btu main cabin AC and then a 13.5 K in the bedroom. The 15 btu is brand new , It’s a Tosot and the specs on it show 1270w input (I remembered wrong). The 700 W midea is window unit that I was thinking about installing because I think it would be more efficient in the bedroom or even the cabin because it’s an inverter style, Not as efficient as a mini split but substantially more efficient than the typical RV you’ve rooftops. I wonder why in the hell they cannot make an inverter style rooftop RV unit I mean, how hard can it be?

How much batteries do you have? And how long will you run your AC unit off the batteries and solar?

 

[corn18]

Just do this now vs. what I did which was bits and pieces of different stuff. Cost me an extra $2k to avoid the simplicity and awesomeness of a fully integrated blue system.

 

[chrisski]

May I ask why you did not go for the Victron inverter? Was it cost or something else? I wish they made like a 3500 W inverter.

No good or bad reason. It's been about three years. I wanted the inverter, battery charger, and SCCs to be separate in case I had to replace them.

I actually have the same set up, a 15 btu main cabin AC and then a 13.5 K in the bedroom. The 15 btu is brand new , It’s a Tosot and the specs on it show 1270w input (I remembered wrong). The 700 W midea is window unit that I was thinking about installing because I think it would be more efficient in the bedroom or even the cabin because it’s an inverter style, Not as efficient as a mini split but substantially more efficient than the typical RV you’ve rooftops.

I don't know what the watts on my AC say, the spec sheet did not come with it, but the 1470 watts is brand new.

For the smaller AC, I don't see how an AC with less BTUs will put out more cooling. I've found mini-splits stop at 120 volts and 12 k BTUs, so I'm reluctant to install a 12 K BTU minisplit to replace my 15 K BTU unit despite being told "I will be fine." Too much money and time for me to try the swap.

I wonder why in the hell they cannot make an inverter style rooftop RV unit I mean, how hard can it be?

Lippert may release an 18 K BTU inverter AC soon. I believe it will be in the Furion Chill product line. There are a couple of YouTube videos but have not found it for sale yet. Here is the spec sheet.

How much batteries do you have? And how long will you run your AC unit off the batteries and solar?

I have details in my signature block.

I can run my AC throughout the day with no issues, and for hours at night. The longest I ran off solar and bateries was 6 hours in the day.

I have a 13 kWh battery pack and the AC takes 1700 watts from the batteries. To do this, I fill my roof up with 1650 watts of panels and have 900 watts at night.

With your plan for rooftop panels, just be sure to include obstacles like the air conditioner itself, and vents, and skylights. I can not physically place much more on the roof.

 

[rockwind1]

Just do this now vs. what I did which was bits and pieces of different stuff. Cost me an extra $2k to avoid the simplicity and awesomeness of a fully integrated blue system.
View attachment 213035

HOLY CRAP!

that is way more conplex than i was thinking. that is the inverter i was looking at though.

 

[Delmar]

I would attempt to be the most efficient. Your air con system is dumping heat outside, while you are making new heat for the water. Electric resistance heating is super inefficient.

Look for an air conditioner with a water heat exchanger. Just pump around the heat you already have instead of making more. Marine air conditioners can run on DC and are setup with the heat exchanger.

I have a heat pump water heater in my garage and love having the cooling.