Community Forums

Dank1945 · 02-09-2019, 03:04 PM

Hi,
I am trying to figure out how many watts do I need in solar panels in order to feed 120V to my Dometic fridge and occasional microwave or small vaccum use. It seems RV parks are ripping us off with their kilowatt charges, and it may make sense to instal solar panels and an inverter.
Thanks for any responses.

twogypsies · 02-09-2019, 03:19 PM

We boondocked for weeks at a time using 300w of solar. That's in the West where there's sun most of the day.

creativepart · 02-09-2019, 03:36 PM

First, there is no way to answer your question accurately. There are a zillion details that are missing in your question. Load requirements, battery type and capacity, the RV’s location, is it sunny, how long per day?

See it’s not possible to answer this question.

Second if you want to do this to boondock away from a shore power source then OK. But I f you want to do this to not be charged an electric usage fee at a RV Park for long term stays you’re barking up the wrong tree. Your cost to purchase the equipment you need would cost more than many years worth of paying for electricity in your RV Park.

jcussen · 02-09-2019, 03:37 PM

As many as you can fit and afford.

twinboat · 02-09-2019, 04:53 PM

Run the fridge on gas. They suck to much power on 120 volts. Some as much as 500 watts.
At 12 volts that's 41 amps from your batteries thru the inverter.

Since the sun doesn't shine all day, you'll need 2000 watts of solar and 600 to 800 AHs of battery to get thru the night.

The microwave is much less of an energy hog, only because it runs a few minutes at a time.

knit · 02-11-2019, 06:16 AM

Probably between 200 and 800 Watts. What size house batteries do you have now? Do the get charged by your alternator while driving?

Maybe start to figure out what is needed by looking at a few web sites from companies that sell complete packages of panels, batteries, inverters, chargers and everything needed to hook it up. Most of these sites have tools and information about how to size a system.

https://www.letsgosolar.com/solar-pa...panels-for-rv/
https://amsolar.com/trailers
https://www.renogy.com/products/solar-kits/rv-van/
https://gpelectric.com/application/rv-solar-kits/

Maybe also call around to RV service places in your area and see who offers to install solar systems.

There are also portable panel based systems that you might consider.

Once you get a feel for what’s needed and how much it costs then you can make the call on if it is worth it. My guess is that if you always stay at campgrounds with electrical hookups it’s going to cost to much.

60sumtin · 02-11-2019, 06:55 AM

Quote:

Originally Posted by creativepart

First, there is no way to answer your question accurately. There are a zillion details that are missing in your question. Load requirements, battery type and capacity, the RV’s location, is it sunny, how long per day?

See it’s not possible to answer this question.

Second if you want to do this to boondock away from a shore power source then OK. But I f you want to do this to not be charged an electric usage fee at a RV Park for long term stays you’re barking up the wrong tree. Your cost to purchase the equipment you need would cost more than many years worth of paying for electricity in your RV Park.

Good answer. I agree.

Harrysait · 02-11-2019, 07:29 AM

How many watts for each panel?
If 300 each, maybe 3. If 50 watts each maybe 20 panels!
Will they tilt?
Will they stay on the ground?

Freqz · 02-11-2019, 08:27 AM

Quote:

Originally Posted by creativepart

First, there is no way to answer your question accurately. There are a zillion details that are missing in your question. Load requirements, battery type and capacity, the RV’s location, is it sunny, how long per day?

See it’s not possible to answer this question.

Second if you want to do this to boondock away from a shore power source then OK. But I f you want to do this to not be charged an electric usage fee at a RV Park for long term stays you’re barking up the wrong tree. Your cost to purchase the equipment you need would cost more than many years worth of paying for electricity in your RV Park.

Yep.

Run the fridge off propane or, if you must, convert it to a compressor style for ~$1200. They’re shockingly inefficient on electric. I’m still not sure the payback is worth it though.

jbrv · 02-12-2019, 08:21 AM

Solar panels dont feed 120 to your fridge or other items.

Solar panels provide 12 volts to charge a battery (there are exceptions). Most times thate 12 volts goes to a charge controller then into the battery.

The battery then provides 12volts to an inverter that makes 120 to power things like the fridge.

Easy answer on how much. as many as can fit on the roof and get full sun. Bad news is the panels are just a small part of what is needed for a solar system to work.

FatChance · 02-12-2019, 10:25 AM

And once you determine how much the whole system costs, divide that by your average monthly cost the RV park charges you for electricity to determine how long your pay back will be. Then, compare that to how long you expect to keep your current RV to determine if this will pay for itself or not.

Alan_Hepburn · 02-12-2019, 11:41 AM

Keep in mind that the power specifications of a panel are under ideal conditions, and will most loikely never be seen in the real world. The system installed on our house is rated at 4 kW - but it has never generated more than just under 3 kW due to cloud cover, shadows, sun angle, atmospheric haze, dirt on the panels, etc. So, if you determine that you need to provide a full 4 kW then you better size your system for 5 or 6 kW...

Brecklundin · 02-12-2019, 01:13 PM

OP... watch this and rethink it....this couple built their system for actually a good price. but the fridge upgrade sold me of an option I never knew about.
https://youtu.be/Yte1V3CkDrw

oatmeal · 02-12-2019, 01:38 PM

Quote:

Originally Posted by Dank1945

Hi,
I am trying to figure out how many watts do I need in solar panels in order to feed 120V to my Dometic fridge and occasional microwave or small vaccum use. It seems RV parks are ripping us off with their kilowatt charges, and it may make sense to instal solar panels and an inverter.
Thanks for any responses.

I have 1,050 watts of solar panels, and on an average/good day in the southwest US in the late spring (pretty favorable conditions), they produce about 3.5 kwh of electricity a day. At 15 cents/kwh, that would save me 50 cents/day in electricity.

And even that amount of solar wouldn't keep up with my refrigerator. My 4-door Norcold uses about 6 kwh of electricity a day. It's a huge energy hog compared to electric residential refrigerators (those run around 1.5 kwh/day). At 15 cents/kwh, my Norcold costs about $1/day in electricity.

To compare--that same Norcold uses 1/2 gallon of propane a day. You can plug in your price for propane (along with your price for electricity) to compare.

The bottom line is that you'd need a huge amount of solar to keep up with a refrigerator that uses 6 kwh/day of electricity.

Don't be fooled by people who claim to slash their electric bills by using their solar even when hooked up to shore power. Invariably, it will turn out that they switched their refrigerator and water heater to propane, yet they don't account for the increased cost of propane in their "savings."