Copyright © 2002-2017 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.

. 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 For parts and design help from the residential solar market try (first) Northern Arizona Wind and Sun 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 easily 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. They also install Lithium battery banks, onsite. Brian Boone used to work for Discount Solar in Quartzsite, and now has his own mobile installation business. I've not personally worked with him, but based on what I've seen I'd recommend him. You may contact him via his blog: https://gotsolarinstalled.blogspot.com/

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. Starlight is a provider of Lithium battery banks, and they also ship them. If interested in an installed Lithium battery system, then Starlight and AM Solar are the two I would look at. 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 Mayo, Florida. "Handy Bob" (Bob Shearer), like me, used to do RV installs. He no longer does them, but his blog is still an interesting read. 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. 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, or if Brian Boone is working in Quartzite then use him. Brian spends part of the winter there. Presentations My presentation on RV Solar and Electrical from the 2016 HDT Rally can be found HERE. This is a pdf file stored in Google Drive. If you have issues accessing it email me and I'll fix you up. If you use this presentation you don't need the previous years ones.

Introduction to Solar

Determining Your Needs

Boondocking Made Easier

A Phased Approach

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.

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). 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:

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+. 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. 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. 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. 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. 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.