Last updated: 09/12/2014

RV Electrical and Solar

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Copyright 2002-2013 John Mayer. All rights reserved. For reuse policy see Reuse Policy

Warning:
 
In this section I describe various wiring techniques and electrical designs. These generally conform to the national electrical code, but it is up to YOU to determine their suitability to your situation. DO NOT take this as electrical advice, only as possible design considerations. If you do not understand basic residential wiring and 12-volt automotive wiring then you should not undertake any of these implementations without further help and advice. If in doubt be sure to get help. Electricity is dangerous. The high amperage DC electricity obtained from the large battery banks described here is suitable for welding and can easily kill you. Do not underestimate the danger involved in working with DC power!!

The information I present here is intended to get you started - it is not intended to give you detailed designs that you can implement directly! Every RV implementation is different, and will require specific design goals to be addressed. However, most of the major issues and considerations are discussed here. If you understand most of what is presented here then you will likely end up with a good system - even if you have someone else implement all or part of it.

Note: the links below may take you to another page in a separate window. In that case just close the window to return here.

In this Section:

Installers
Presentations
Introduction to Solar
Determining Your Needs
A Phased Approach
Why Many Systems Do Not Work Well
The Golden Rules of RV Solar and Electric
Equipment Recommendations
Residential Refrigerators
AC Circuit Protection

Our Systems (since 2000)

The following more detailed topics are on individual pages:

RV Electrical System Schematics
 
Solar Panels and Solar Controllers

Inverters, Chargers, Converters

Batteries and Charging

Wiring

  • Rooftop and Solar Controller Wiring
  • Solar Array Wiring Considerations
  • Cables and Battery Connections
  • Hints on Cable Building
  • Solder or Crimp?
  • Batter to Inverter Wiring
  • Interfacing to Your Loadcenter
  • AC Wire Types
  • Grounding
  • Neutral Bonding 
  • Installing a Sub Panel
  • Powering the Entire Loadcenter
  • "Splitting" a 50-amphere Loadcenter
  • Monitoring and Control
  • Recommendations

Sample Solar and Electrical Systems



I'm assuming that you have a basic understanding of both 12-volt and 120-volt power. There are many excellent tutorials and books on both subjects. I won't repeat the information here, but leave it to you to explore on your own if you don't understand the basics. For basic 12-volt electrical info, try Mark Nemeth Electrical Info which is Mark Nemeth's article on 12-volt power. For wiring techniques and parts check the The Truck Electrical Center section of this site. The information there is oriented to upgrading an HDT truck, but is generally applicable to RV's.
 
For an understanding of various RV and house connectors, and proper wiring, check out http://www.myrv.us. This will give you an understanding of basic RV electrical service, and how it differs from residential electric.

If you have a basic understanding of AC/DC electricity then you should be able to design a reasonable system following the recommendations in the sections below. The system designs and components used are only examples, and need to be modified to meet your needs. You need to complete the entire design before you start implementation or you might find your system unable to meet your future expansion needs.
 

For parts and design help from the residential solar market try (first) Northern Arizona Wind and Sun. They have an excellent forum with true experts posting on it, and their store has reasonable prices. Do not underestimate what you will learn from reading their forum. Every time I go there I learn something new! After them try http://www.backwoodssolar.com. I'm also willing to answer questions and help in design if you contact me directly - see the About Us section for our email address.
 
A complete implementation of anything but the smallest RV solar system, including an inverter, and batteries (from scratch) can cost in excess of $3000, depending on sizing and components selected. Time spent in the design phase is time well invested. Mistakes can be expensive. If you have the system installed instead of doing it yourself make sure you find a good installer. You want someone who will charge by the hour - not a flat rate. You are more likely to get a good job if the installer is not rushed, or losing money on the work.

Installers

If you need help with system design you can work with a single vendor for most of your system components and they should be able to provide design help. The best thing is to work with someone who understands the special needs of RV's. Although for many years I did solar/electrical installations, I no longer do installations. I still do designs.

For installation, one of my top choices in the West would be AM Solar (Greg Holder). Their business is RV solar, they can supply almost all the required solar parts, their prices (for the most part) are reasonable, and their preconfigured systems are sufficient; AM Solar.

John Palmer (Palmer Energy Systems, Palmer Energy) also specializes in RV solar systems. In the East that is who I would use - he is located in Florida.

If you need an installer in the Phoenix area then check out D&R Family RV, Glendale, AZ, 623-842-1265.

In the Yuma area Starlight Solar has a good reputation. I never worked with them directly but have observed their systems, and like what I have seen - especially in the last 3-5 years.

If you are looking for an independent installer that travels around (mostly in the West) then check on "Handy Bob" (Bob Shearer). You might also be interested in his blog. We agree on most installation issues and techniques - although he is generally more opposed to generators than I am. One thing we do agree on, and always have - there are really a lot of bad solar installations out there. It is very difficult to find a good installer - although in my opinion things have improved in the last ten years. If you want a good evaluation of your existing system done, Bob can do it. If he was near me then I'd use him first.

As far as installers in Quartzsite go, I find it hard to recommend any of them. If I had to use one I'd use Discount Solar. But frankly, if you are in Quartzite it is simple to go down to Yuma and talk to Larry and Debbie at Starlight Solar.


Presentations

My presentation on RV Solar and Electrical from the 2011 HDT Rally can be downloaded from here. (809 KB PDF) If you use this presentation you don't need the previous years ones.

My presentation on RV Electrical and Solar from the 2010 HDT Rally can be downloaded from Files/Presentation HDT RV Electrical 10_13_2010.pdf  (421KB PDF file).

My solar and electrical presentations from the 2009 HDT Rally can be downloaded from RV Electrical Presentation - HDT Rally 2009.  This is a PDF file (434KB). It is similar to the 2010 presentation, but not the same. Robb Finch's presentation on Wind Power can be downloaded from Wind Turbines - HDT Rally 2009 (PDF, 1.2 MB).

 

Introduction to Solar

The ability to dry camp, or boondock, is inherently part of the capabilities of all RV's. The amount of time one can live effectively "off-grid" is dependent on your water storage capabilities, and the size of your battery bank (or how much you want to run your generator). Most RV manufacturers do not provide advanced boondocking technology as a standard part of their RV's, so you are usually limited to 2-4 days without hookups. Enhancing the standard RV's capabilities can allow you to live indefinitely without hookups.

So what do you need to effectively live off grid indefinitely? The heart of your system is the battery bank. You will need enough battery capacity to supply your energy needs. That means translating some of the DC battery power to AC, so it can be used by your normal RV appliances. You do this with an inverter.

Next, you need a way to replenish the battery power you use. That can be either a generator in combination with a modern battery charger, or solar panels in combination with a solar controller. Or a little of both, which is what many people use. Solar is really an option here. You can live effectively off grid with just a generator, a proper charger and a reasonably sized battery bank; but for long term use you will find it most convenient to combine this with some solar panels.

You also need a way to monitor the status of the system. Without monitoring the system you will not know how much energy is available for use, or when to use the generator to help recharge the battery bank. If the battery bank is the "heart" of your electrical system, then the monitors are the "brains". You need them both.
 

To live effectively off grid you also need a way to remove waste water, restore fresh water, and efficiently heat the RV (when required). These last three items are not covered here. This article concentrates on energy-related items.

 
Side Note: typically a "blue boy" is used to remove waste water, either gravity fed or in combination with a macerator pump. The simplest way to restore fresh water is with a plastic water bladder (check Camping World for a nice 45 gallon one that works well). The bladder folds down to a very small size when not in use. Heat is efficiently supplied with a catalytic or "blue flame" heater. This uses no power to run, saving your battery power for better uses than running the furnace. It is also nearly 100% efficient in its use of propane. Your furnace is only about 60-70% efficient. For more on these topics see Boondocking Made Easier.
 
I've tried to convey what to look for in each of the areas covered. Although I have made some specific recommendations, you should not assume that these are the best available choices at the time you read this. Electrical and solar components change fast. Manufacturers continually upgrade their products, and introduce new products.  The intent of the information provided here is to help you to identify and select the products that will work for your particular implementation. There are many tradeoffs that need to be made when implementing an alternative energy system for your RV. There is no "right answer" in many of the areas - it is a personal choice with tradeoffs only you can make. The sample systems work well together and should satisfy the needs they are sized for, but they are only samples and there may be better components at the time you read this. You should assume that the recommendations here are my personal preferences - there may be (and are) other valid choices in equipment.
 

Determining Your Needs

First, you need to be realistic with your expectations. If you expect to install a solar system and use power just as you did when hooked to shore power, then you will be disappointed. Despite what some may tell you, living with an alternative energy system in an RV requires conservation. This is because, unlike off-grid home applications, most RV's cannot store enough batteries to allow a large enough system for unregulated energy consumption. You need to learn to minimize use of high-power-consumption devices, supplement your existing RV systems with more efficient devices (such as using a catalytic heater instead of your RV furnace, which uses great amounts of 12-volt power), and monitor your energy use so you know when you are in trouble. Running out of power when you really need it is not fun. Killing your battery bank because you drew it down too far is even less fun - batteries are expensive.

You also need to examine your motivations for wanting solar. Solar use, and living "off-grid", is a lifestyle decision. Adding an effective solar system to an RV will rarely pay back the costs of installing it. Nor will you recoup your investment when selling the rig. The best (and really only) reason to add solar is so you have the option of boondocking for long periods of time without hookups. If you do not enjoy doing this, then you should reflect on why you want to install a solar system. One or two days of boondocking between sessions of hooking up to shore power does not require  solar, and its auxiliary systems. You can get by for a couple of days on a reasonable size battery bank. If you need 120-volt power, consider adding an inverter/charger. If you then find you need to recharge the batteries without shore power, you can consider adding a generator - either a small portable one, like a Honda 2000, or a genset that is permanently installed. If you have a motor home, you likely have a genset already and probably even an inverter. Notice, there is no solar system here. You really don't need one if you are just overnighting occasionally.

Need to run your air conditioning? Well, a solar system is not going to help you here. It is not realistic to expect to run an air conditioner on a battery bank. You need a properly sized generator to run air conditioning "off-grid". (Note: small window units and "mini-split" AC systems could be run for short periods of time off a large battery bank, but from a practical view, this is just not feasible for long periods. Large residential solar systems can have air conditioners run off them - but we are focusing on RV systems here.)


OK, so you like to boondock for long periods of time. You've decided that you can afford to invest $3000+ dollars  to make your life more pleasant when boondocking. How big of a system do you need? Only you can answer that. You need to examine your lifestyle while boondocking (or your anticipated lifestyle - you don't actually have to boondock) and figure out how much power you use. Figuring out power usage while connected to shore power won't give you your answer, because you are using lots of electric devices you won't use when you boondock. For example: electric hot water heater, RV refrigerator on electric, battery chargers plugged in, converter on, lots of lights on, cooking turkeys in the microwave (just kidding).

A side note on system cost. Some would argue that $3K is way too high, and that you can implement a system for far less. While this is true if you implement a very small system, a complete system that will run most of the major items in your RV, and has the convenience of remote panels and a whole-house inverter/charger is going to cost in this ballpark and up.
 

So, how do you figure your power use? Think about what you have to use and add it all up. You can figure in watts, or in amphours. Watts is probably easier, but ultimately you will need to convert to amphours so I suggest you do your figuring in amps to start with. Look on the electric plate on the various devices and it will tell you what the device uses power-wise. Add them all up for the amount of time you run them. Don't count any 120-volt lights, because you will only use 12-volt lighting while boondocking. Remember, you can figure watts by knowing the voltage and the amperage that the device is rated at - both are on the electrical plate (and if you are lucky, the wattage is there) watts=volts x amps. Sometimes electric plates on devices list ratings as xxVA (e.g. 40 VA) - this is watts (VA means Volts x Amps; actually there is a little more involved with VA because it accounts for power factor, but we will ignore all that for this discussion).

Here are the magic formulas that you learned in high school physics class and forgot after your test.

watts=amps x volts
volts=watts/amps
amps=watts/volts

And for some shortcuts: if you know the AC amps just multiply by ten. Four amps AC is 40 amps DC.

When you work with solar it is best to figure everything in DC voltage, because your battery bank is DC - that usually means converting all your AC measurements to DC. In electrical stuff, watts is the universal measure. If you have a watt rating on a 12-volt appliance, it can be directly added to the watt rating of a 120-volt appliance to get the total watts consumed. Amperage ratings have to be converted, based on the voltage. Sounds complicated, but some simple math will allow you to get the total DC amps consumed from your battery.

Here are some 12 volt examples: 2 - 20 watt lights for 4 hrs= 40 x 4 = 160 watts, refrigerator 2 watts for 24 hrs = 48 watts. Now you have to figure your 120-volt loads: hairdryer 1500 watts for 12 minutes = 300 watts.  Microwave 1000 watts x 5 minutes = 83 watts. So all total we have (160+48+300+83) 591 watts in a 24 hour period. To convert to amps, divide by 12 or 120 - whichever voltage you are figuring for.  We did not count TV, satellite receiver, etc. You need to add up everything. Why did we count the refrigerator in our example when it is running on propane? Because, even when on propane, the refrigerator uses 12-volt power for its control circuits.

With an estimation of the number of watts you use on a daily basis you can calculate how many panels you need to supply that, and estimate how long you will have to run your generator to fill the "gap", if generator use is part of your energy strategy. Don't forget to add in "phantom" loads. For most smaller RV's, these average around 2-3 amps DC (per hour). (Note: larger motorhomes and large 5ers can have a phantom load of 12-18 amps DC per hour, depending on the RV.) These are loads that occur when it seems everything is "off". They come from battery chargers, electronic boards in your propane appliances, propane and CO alarms, etc. You also need to factor in the inefficiencies of converting/using power. There is energy lost when inverting, and energy lost in wire runs. The rule of thumb is 30% lost when inverting, and 20% lost in direct 12-volt battery use. It generally will not be more than this - it may actually be less, depending on your system.

Don't get obsessed with figuring exactly what you need. Just get close and then usage will allow you to adjust. As a rule of thumb, the average RVer uses between 75 and 125 amphours of DC per "cycle" (partial day and overnight). Remember, when you are using power during the day (while charging) your instrumentation is not giving you a true count because power is being supplied while you are using it. The nice thing about a properly designed solar system is that you can easily expand it by adding panels (as long as you buy a large enough solar controller initially, and wire everything for future expansion). For an excellent discussion of sizing your system take a look at Mac McClellan's website Electrical System Sizing. Throughout the discussion here I'll continually "harp" on building for future expansion. It costs little additional when you design/build the initial system, and is lots of additional expense later if you do not do it.

 

A Phased Approach

 
If you are not sure you will boondock a lot, or are overwhelmed by all that is required to implement a complete system for extended boondocking, consider using a phased approach. This will allow you to implement portions of the complete system, evaluate your use and needs, and then expand your system if you find it is beneficial to you. Here is my recommended approach: 
  1. Batteries. First I would augment my battery bank by upgrading to at least two 6-volt batteries. (I am assuming you have the typical RV with one 12-volt battery.) This should be able to be done to any RV without too much trouble. It will double the time you can boondock, and the 6-volt batteries will generally perform better than most 12-volt batteries. See the battery section for recommendations. Cost - $150+.
  2. Battery Monitor. Next, I would add a battery monitor - one with cumulative amp hours. This will tell you how much battery capacity is left, and will let you know when the bank is properly recharged. There is no other effective way to accomplish this that is convenient. Expect to pay around $160-$180 for a Trimetric RV2025 or RV 2030 with shunt.
  3. You will learn more about your use of power with the battery monitor than any other
    way. The single most important instrument in your RV is the battery monitor.
  4. Charging. You need a way to recharge your battery bank. It may be that you don't boondock long enough that you deplete the bank - but if you do you need a way to charge. Typically this is a generator of some sort. If you have a motorhome  you probably have one already. If not, look at the portable Honda's and Yamaha's in the 2000 watt range. They will not run an air conditioner, but they will very effectively recharge a battery bank and run a microwave. If you use your converter as the charging source, look into a charge wizard or upgraded charging capability for your converter. Most older converters (pre 2005) do not have an effective battery charger in them. Switching out converters is covered more at the end of the Inverter/Charger section. You will want a high output battery charger to take advantage of your generator. 
  5. Inverter. At this point you should have some experience boondocking and know what size inverter you need. Either you will need a large one to run the microwave, or you can get by with a smaller one that just runs your TV and other occasional small appliances. If you start with the small one and decide to add a larger one later you could use the small one for just your entertainment center, or you can sell it.  Most people who boondock for longer periods will want an inverter of some sort.
  6. Solar. If you boondock enough, and for long enough, you will eventually want to add solar to avoid running the generator. Solar is relatively expensive but has come down in price in recent years. Expect to pay about $1.00 to $1.20 per watt with shipping, although you can find panels in the sub- $1 range.

Back to Page Contents

Why Many Solar Systems Do Not Work Well

Many people complain that their systems do not provide them the time off-grid that they expected. I've been designing and installing systems since 2000, and I routinely hear these complaints. Almost always when you evaluate these systems it is an installation issue. Very few systems installed by RV manufacturers are done in an optimal fashion. Even dedicated "solar installers" often do not match components correctly or configure the system optimally. That is one reason I encourage people to implement their own systems, where they have the desire and the minimal necessary skills. Even if you do not do the installation yourself, designing the system will teach you enough to ensure a good installation by others.

The common problems/issues I encounter are:

  • The system is under-wired. The wire run from the solar panels to the controller, and then on to the battery bank, is sized too small. It should never be less than #6 cable, and I use #4 routinely on 12-volt nominal systems. Manufacturers commonly use #10. That is way too small for all but the smallest system. The only exceptions to this are with higher-voltage systems (more on that later). USE the wiring tables or online calculators to determine the correct size wire, and then go a little heavier. The wire size is not an "opinion" - it is simple physics. Use the calculators.
  • The solar panels are shaded at certain times of the day. Why an installer would place panels where they KNOW they will get shaded is a mystery. But it is not that uncommon. Even the shadow of the shaft of a TV antenna can kill the output of a panel. You want NO SHADOWS. More on this later....
  • The solar controller is too far from the battery bank. Put it as close as practical - but not in the same compartment. Do not use a controller that has an in-built display and place it in the RV so you can read it, instead use a controller with a remote display capability. Separately calculate the wire size needed from the controller at max output to the battery bank - this will likely be heavier than what is required from the panels to the controller.
  • The solar and charger settings are not optimal. On flooded cell batteries the absorption setpoint (the bulk charge rate) should be 14.8 volts UNLESS your battery manufacturer says otherwise. (Only pay attention to the battery manufacturer. Installers and even controller manufacturers will routinely provide you with bad information.) The default settings for wet-cell batteries in almost all controllers/chargers is 14.4-14.6 volts. That is not adequate to get a good charge on the bank. The other common issue is that the controller does not allow enough time during the absorption phase of the charge. Thus, the bank never approaches a "proper" charge.
  • Battery temperature sensors are not employed. To get a proper charge, both the inverter/charger and the solar controller should have a battery temperature sensor placed on the battery bank. The charge voltage varies depending on battery bank temperatures. It is difficult to get a good charge without the temperature sensors. If the inverter or solar controller offers a voltage sense line then that should be used as well.
  • Batteries are not checked and equalized when they should be. You need to check the battery bank water levels at least monthly until you learn your system. You need to check the batteries with a hydrometer at least two times a year and equalize if required.
  • Battery terminals are dirty and/or loose. You would not think this would be that common, but it is.
  • There is no instrumentation that records cumulative amphours drawn from the battery bank. Without this information it is difficult to evaluate the current battery condition. As a result, many battery banks are drawn down too far and their life is unnecessarily shortened.

The Golden Rules of RV Solar and Electric

This is a summary. Details are covered in the following sections. These are my opinions based on experience and education - you certainly do not have to follow these guidelines. But if you do, you will have a successful system if properly implemented.

Panels

  • Use high voltage (over 28 volts) on any but the smallest systems (small: under 400 watts)
  • Optimal input voltages for most MPPT controllers outputting to a 12-volt battery bank is in the 30-50 volt range.
  • Price panels on a per-watt basis. There is not much difference in panels unless you have special needs.
  • Use serial/parallel connection to get higher voltage, when required. Panels must be matched.

Solar Controller

  • Use an MPPT controller; high voltage; boost in the 10%+ range is realistic; price differential over PWM is not that great these days and for a larger system it allows many benefits ("larger system" = around 500-600+ watts)
  • Controller must allow adjustable voltage and charge times
  • Position close to the battery bank
  • Make SURE the wire size to the batteries is correct. It will be bigger than what comes from the roof in most cases.
  • Temperature compensation is NOT an option - use it. If a voltage sense line is available, use that too.
  • Fuses/breakers on input/output sides.

Batteries

  • Balance the system; have enough batteries for the amount of watts of panels you have (you can have more, but having less is wasteful)
  • Rule of thumb: 1 amp of storage for each watt of solar panel.
  • Flooded cell batteries charge at 14.8 volts NOT at 14.4/14.6 volts that you commonly see
  • Wire correctly: large enough wires, +/- connections on diagonal corners, equal length wire runs.
  • AGM batteries have advantages, but cost much more
  • Solar alone often will NOT bring a bank up to "full" state of charge because the system is continually in use. But if properly designed it can.
  • Use a battery monitor with a remote display (like a Trimetric, Link, or Magnum BMK)
  • With flooded cell batteries check specific gravity at least every 6 months. Equalize if required.
  • A desulfator "may" be helpful. Reports vary in RV use.

Inverter

  • Wiring is critical. Never less than 2/0 and usually 4/0. READ the book - there is no excuse to use a lighter wire than the manufacturer requires.
  • Short distance to the batteries. NEVER more than 10' max.
  • Catastrophe fuse
  • Remote display/control is important
  • Do not use too large an inverter for your needs. It is inefficient.
  • Charge section is critical if using AGM batteries. You want a LARGE charger with AGMs.
  • On flooded cells properly set the charge amperage. C/20.
  • Wire through a subpanel. Wired in-line is OK for a 30-amp RV, but a subpanel is preferred. Do not wire 50-amp in-line unless the inverter has a 50-amp rated transfer switch (which is no longer available).
  • Temperature compensation is NOT an option - use it.
  • Build in provisions for removing inverter for service or upgrading your RV - AC wire length and junction box. If you have a converter leave it in place but disconnected from shore power. This can be used if the inverter/charger fails.

Wiring

  • Wire size is CRITICAL. It is the single-most common issue with installations. Use voltage/distance calculators. Then go heavier
  • Manufacturers almost never provide adequate wiring
  • Wire for 2% loss or less. I wire for 1% from the controller to the bank.
  • Use quality closed-end, coated lugs, and properly attach them; use dielectric grease and adhesive heat shrink
  • Fuse before/after controller; catastrophe fuse at battery bank
  • Use combiner on roof; I prefer a breaker box on larger systems. With high voltage systems the combiner can sometimes be in the main compartment and not on the roof, but calculate the loss on the #10 wires from the panels to see if this works.
  • Use distribution buss bar(s) near battery to tie loads together (if required)
  • Do not attach loads between shunt and battery.

Equipment Recommendations

I get asked often what I recommend, and that changes over time. The industry is constantly developing new products. What follows are my recommendations at the time I wrote this. Make sure you check these against your own needs, and against current technology. Although I try to keep this up to date, there is no guarantee. If you see something new that you think is better, feel free to write me about it, and why....

  • Magnum inverters. Also look at the BMK (battery monitor kit). Many people prefer the Trimetric - as do I.
  • Morningstar solar controllers. Personally, I like the MPPT 60 and its ability to directly network to your router. For larger installations, MidNite Solar has the Classic 150 which allows more panels to be used (otherwise you have to "stack" 60 amp controllers).
  • Solar panels:  Sun Electronics solar panels (lots of choice and reasonable prices, look at some of the blemmed products). AM Solar has a new 100 watt panel out - the GS100 (as of 4/14/2011). This is worth looking at. It has a high efficiency rating, and is narrow, so 4 fit across an RV roof, and it fits next to an airconditioner. But they are not cheap. Wholesalesolar.com has very good prices on a variety of panels. They "can" be cheaper than Sun, it just depends. Look at them both. I like the SolarWorld panels available at Wholesalesolar. USA made, excellent warranty, good efficiency and priced reasonably.
  • MidNite Solar breaker boxes, and combiner boxes. I like the ones with breakers in them, but there are other methods of protection that do not use breakers. AM Solar has a new combiner box that allows for larger wires.
  • Bogart Engineering Trimetric battery monitor RV2025 or RV 2030 is still my favorite. I had a Magnum BMK in my 2012 coach, and wished I had a Trimetric. My 2015 coach has a Trimetric TM-2030.
  • Look at the Magnum mini-panels (MPP) or the MidNite Solar E-Panel if you are doing a higher cost installation. They run about $600 but solve most of your wiring issues in one UL approved box. On a higher-end implementation you likely will be 75% of that with your own wiring. And there are extra advantages to these boxes. The MidNite E-Panel is probably best suited to most RV installations because of the dimensions (it mounts the inverter on the front of the panel), but in many cases neither of these will fit. This is for high-end systems only...otherwise the cost is not justified.

 

Residential Refrigerators

In the past few years I often get asked to design solar/electric systems for RV's with residential refrigerators. Since the late 2000's the energy efficiency of these refrigerators has improved enough that it is possible to both boondock and have your residential refrigerator. For avid boondockers having the electric refrigerator is likely too much of a compromise unless you have a very large solar/electrical system. But for people that do not boondock for months on end, it is now a viable alternative with a large solar system, or a combination of a medium system and an hour or so of generator time a day. As always, your usage habits and the compromises you are willing to make will factor into the decision to go with a residential refrigerator.

In general, these refrigerators add about 100 amp hours (DC) to your electrical burden (per 24 hrs). You need to replace both that, and whatever else you use for power. There are things you can do to minimize this usage some, but in general plan for 100 Ah.

I have a spreadsheet you can download with examples of generator runtime, various refrigerators, and some of the other planning factors involved with designing a system around a residential refrigerator. Take a look at it and see if this direction meets your needs. If you have suggestions or see errors in the spreadsheet let me know. Most of it has been validated with actual in-use systems.

 


AC Circuit Protection

When revising your electrical system you should consider the addition of an AC power management system. These provide protection from miswired pedestals, high and low voltage conditions and surge suppression. They have a remote display that shows you line loading (so you can figure out exactly how much AC you are drawing on each leg of your box). It is best to use models that are hardwired, instead of external surge guards. Hardwired models are theft proof, and you won't forget to put them out. The time you forget to plug it in will be the time you really need it. They are available in 30-amp and 50-amp versions.

 

The Progressive Industries model 40240 (50-amp model, $494) is available at Camping World and other outlets. I highly recommend this capability - not only do you know what is going on with your AC loads, but you are protecting your coach AC system. From a design perspective, I prefer placing the device directly "next to" the loadcenter if you are using a sub panel. If wiring the inverter in-line then place the management system before the inverter. This will offer protection to the inverter from surges and spikes.

 

In my opinion, EVERY RV should have an electrical management system like the Progressive Industries version with the remote panel.

 

 


 

 

 

Our Systems (since 2000)

 

On Our 2000 Newmar

  • Heart 458 modified sine wave inverter installed as a whole RV system (30 amp coach).

  • Trace C60 PWM charge controller

  • 5 x Kyocera 120 watt solar panels.

  • Link 1000 battery monitor

  • 6 - Sam's Club golf cart batteries or 6 - Trojan T105's.

 

On Our 2001 Royals International

  • Heart 458 modified sine wave inverter installed as a split panel system (50 amp coach).

  • Trace C60 PWM charge controller

  • 5 x Kyocera 120 watt solar panels.

  • Link 1000 battery monitor

  • 6 - Sam's Club golf cart batteries or 6 - Trojan T105's.

On Our 2010 New Horizons

  • Xantrex RS 3000 pure sine wave inverter/charger. 50-amp pass thru; wired to a subpanel. 150-amp charge section.

  • Xantrex XW 60-amp MPPT charge controller.

  • SCP networked to both the inverter and charge controller. This provides complete control and monitoring of both devices.

  • Trimetric 2025RV battery monitor.

  • 4 - Sun Electronics Sun SV-T-205 HV panels. Wired as a parallel array. These are the same as Evergreen Panels. They are not UL listed, which gives a far cheaper price. Imp=7.36 A at Vmp=27.90V. MC-4 connectors. Not presently on the rig but everything is set up for them.

  • AM Solar Large combiner box.

  • Midnite Solar "Baby Box" enclosure with 2 breakers to isolate the solar controller input/outputs.

  • 6 - Trojan T-105 6 volt batteries (675 Ah rating). In retrospect going with 4 - L16RE batteries would have given me 650 Ah and it is likely a better battery. But the deal on the T105s was too good to pass up. I'll likely replace with the L16s.

  • 5500 watt LP genset (moved to the 2012 coach).

On Our 2012 New Horizons

  • Magnum MS2812  pure sine wave inverter charger. 2800 watts with a 125 ADC charge section. ME-RC remote display.

  • Magnum BMK battery monitor uses the same display as the inverter.

  • Morningstar Tristar MPPT 60 solar charge controller with remote panel.

  • 4 - Sun Electronics Sun SV-T-205 HV panels. Wired as a parallel array. These are the same as Evergreen Panels. They are not UL listed, which gives a far cheaper price. Imp=7.36 A at Vmp=27.90V. MC-4 connectors. Installed by New Horizons.

  • AM Solar Large combiner box.

  • Midnite Solar "Baby Box" enclosure with 2 breakers to isolate the solar controller input/outputs.

  • Four 8D Lifeline AGM batteries for 1020 Amphours of stored power. Half is usable.

  • 5500 watt LP genset (moved to the 2015 coach).

On Our 2015 New Horizons

  • Magnum MS3013 pure sine wave hybrid inverter. 3000 watts with a 125 ADC charge section. ME-ARC remote display

  • Trimetric RV2030 battery monitor.

  • MidNite Solar Classic 150 MPPT solar charge controller with remote panel and Ethernet connection to our router.

  • 4 - Astrenergy 305 watt high voltage panels for 1220 total watts. Wired parallel.

  • Home built combiner box.

  • 6 - Fullriver L16 AGM batteries for 1200 total Ah.

  • 5500 watt LP genset. This was moved to the 2012 unit from the 2010, and then moved to the 2015 unit.