San Diego California Campground Sunset

RV Solar Series: Introduction

RV Solar Series: Introduction “Boon-docking” or “dry-camping” is an RV style that refers to camping in an RV without the attachment of electrical, water, and sewer hookups.  We bring our own generator to make electricity, sometimes campground rules restrict generator operation hours. The most restrictive generator hours we encountered were at Death Valley National Park where “quiet hours” were between 7 pm and 7 am. 

What time is it?  Here let me show you how to build a watch.

RV Solar Series: Introduction: Our goal is that we can live without the need for outside electricity and without running our generator. We are full-time travelers and a motor home is our preferred mode of travel.  Last year (2018) we covered 8352 miles and nine big western states.  Our ideal locations are National Parks, State Parks, and National Forests. In the west, there is also lots of Federal BLM land that is available for low and no-cost camping opportunities. Our quest to understand and install a solar panel system lead to the writing of the RV Solar Series including this introduction.

If you don’t camp at locations without electrical hookups, you don’t need a solar collector or big battery.

The purpose of a generator in our RV, in our minds, is to recharge our batteries. The purpose of solar is to recharge our batteries without running the generator.  In our case, our generator can also run our air conditioner, but given the size restriction of our solar/battery system, we have no hope of air conditioning from our battery. That is not to say that it is not possible, it is just not within the design of our system.

If you already have a generator, and only camp at locations for overnight stops, without electrical hookups, and if your battery only has enough capacity to get you through the night, and then you leave in the morning — you don’t need a solar collector system.  Your current generator and the fuel to run it, or your engine alternator, as you are driving will recharge your battery at a lower cost than a solar collector system. Remember you must recharge a lead-acid battery fully after each discharge. 

If your battery won’t make it through the night, you need a higher-capacity battery, not a solar collector.  

Important language note:

The word battery is commonly misused. The meaning of the word battery is a group of cells, combined together to provide a common energy source. Our RV has two boxes (most people would call them batteries), each containing lead-acid cells, the boxes are wired together to form a battery. In fact, in each of my boxes, there is a collection of cells, making each box a battery. 

The cylinder inside your flashlight is a cell the two cylinders together form a battery. If you wire two boxes together, each containing at least one cell, you get a battery.  In fact, if you wire ten boxes together, you still get a battery.  Most people would say multiple boxes wired together would form a battery bank. If the same multiple boxes were not wired together, then the term batteries would apply.  There is no end to the confusion this causes.  For our needs one or more boxes, containing cells we will refer to as battery or batteries interchangeably.

Our battery is 12 volts in name only. The happy range of our battery is about 13 volts. Another need to know is that a lead-acid battery is hard to recharge,  loves to be full, and gives up charge unwillingly. I hope to relate technical concepts in more human-relatable terms.

Battery State of Charge

12-volt Battery graphic
12-volt Battery graphic

In lectures by experts in the RV industry last January (2018) I heard the most common phrase; “You cannot recharge a battery using solar”.  I even heard the phrase “You cannot recharge an RV battery using a generator”.  Both phrases have a nugget of truth to them but are only true if your system is incorrectly sized or installed or operated.  I am glad to report that these statements are not true. These experts are clearly not up to date.

I still have issues of controlling what is going on. I wish I could have more manual control. Much like an automatic transmission in a car, decisions are made without consulting me. Overall we are thrilled with the results.

The following posts will outline how I accomplished a fully functional solar RV battery charger using a combination of parts from the local hardware store and used, yet still very capable solar panels.  It is not the cheapest system and obviously not the biggest, most expensive or most capable system. We tried to and accomplished “just right”.

RV Solar Series — Goals: 

The goal for our solar electric system is that we can live in the RV without the need for outside electric for at least 12 hours from sunset to sunrise  — winter or summer — and then without running our generator, recharge our battery the next day so that we don’t have to run our generator. The second goal is that we don’t need any interaction with the solar system with the exception of watching it work. The final goal is that our system is expandable which assumes that if we have succeeded in our system design or if our system design is not sufficient that it can be expanded without losing previous work or expending the money. I claim success in all the goals and am looking forward to explaining how they were accomplished and building on the success by expanding our system to further supply our energy needs. 

We created this site to help our friends with their RV questions. Feel free to ask questions or comment and we will address them to our best abilities.

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