Solar vs Generator?

Lots of new Airstream owners want to find ways to extend their camping time while “boondocking,” (off-grid camping, away from electrical hookups). So inevitably the question comes up: which is better, a generator or solar panels?

The answer comes down to your needs. Generators are the most practical way to have enough power to run very high-wattage appliances like the air conditioner and microwave oven. If you must have air conditioning when not plugged in, you will have to use a generator, and it will need to be capable of at least 2,000 watts peak output, and preferably more.

However, if you can live without your air conditioner and microwave oven, solar panels become a very attractive option. Solar panels are silent, don’t require you to carry fuel, and are virtually maintenance free (other than washing them once in a while). They work without any intervention from you and can keep the batteries in your Airstream charged while it’s in storage.

A major difference is that solar panels only provide power to charge the batteries. They don’t directly power anything, although the batteries will of course power all of your 12-volt devices and can even power low-wattage 120-volt AC appliances like laptops and TVs using an inverter.

Most RV generators have on-board inverters so that they can provide 120-volt AC power directly to the Airstream, just like plugging in. This is convenient but most of the time the generator is producing far more power than you actually need.

If you want a generator primarily to recharge your batteries while camping off-grid, you can get the smallest generator possible. Even a small 1000-watt (rated) generator can typically produce far more power than the batteries will accept at any given time. The rest of the power is wasted, unless you are running the microwave or some other power-hungry AC appliance while the generator is running.

This means that the best time to use the generator is when power demand is high. It’s much easier to avoid using battery power by being plugged into the generator, than to try to recharge battery power later. Use the generator in the morning and evening when you are cooking and using lights and water pump, and the power needed will be supplied by the generator rather than coming from the batteries.

If you want to get a generator, do yourself and your neighbors a favor and get one of the quieter models specifically made for RV use. Both Yamaha and Honda make excellent products which have good reputations for reliability and quietness. If you borrow a “construction” generator from work on your weekend camping trip you will save some money but you won’t be popular when you fire it up—and the noise might detract from the peacefulness of your boondocking site, so what’s the point? Similarly, there are cheaper “knock off” brand generators on the market, but their quality is not up to the standards of the major brands.

Solar’s big advantage is in recharging batteries, so if extending your time at camp is your primary goal, they are the preferred option. Rather than pumping out large amounts of power in short time periods like a generator, solar provides a steady all-day charge will have a much better chance of getting your batteries up to 100%. It’s like the turtle and the hare. With batteries, slow and steady wins the race.

If you have both a generator and solar panels, use the generator when the batteries are heavily discharged (for an hour or so in the morning, for example) to get the bulk charge done quickly, and then let solar finish the job over the course of the day.

If you only have solar, keep in mind that during the morning and mid-day, moderately or heavily discharged batteries will probably accept every amp the panels can generate. Then the charging rate naturally slows down. If the sun is still shining at that point you have surplus power, and so that’s the time of day to plug in all of your rechargeable accessories like phones, cameras, laptops, etc. This strategy takes maximum advantage of the power being generated.

Sometimes people go with generators over solar because they are afraid they won’t have power on a cloudy day. Certainly clouds will drastically reduce the amount of power generated, but you’ll still get some. The solution is to add batteries so that the Airstream has enough power to bridge a cloudy day (or two) without a problem.

If you are considering adding solar panels, keep in mind that the solar panels should be sized to approximately match the capacity of the batteries in the Airstream. If the panels produce a lot more power in a typical day than the batteries can store, you’ll have wasted money on expensive panels. If the panels are too small, they might not produce enough power to keep the batteries charged, which can lead to short battery life if the trailer is not plugged in regularly (such as during long-term storage).

It’s hard to do an apples-to-apples comparison of generators and solar panels, because as you can see, they perform very differently. It’s even hard to pin down a cost for comparison, because the output of each option can vary widely. Quiet RV generators from Honda and Yamaha range from 1,000 watt units suitable for battery re-charging and small appliances, up to big 3,000 watt units to run the air conditioner. Solar panel systems (including battery banks) can run from 50 watts up (typically 200-400 watts will fit on the roof, plus more possible using portable panels), and the costs of an installed system are likewise varied. Keep in mind that comparing wattages is not useful since the solar panel runs whenever the sun shines, and the generator usually only runs for short times.

You’ll need to decide which option you prefer, and then talk to a solar installer, or shop generator prices. RV solar specialists are in many parts of the country (some are even mobile and will come to you) and they can help determine the optimal size of your battery bank and provide solar panels to match.

Either way, upgrading your Airstream to give you more boondocking time is a great advantage. It will open up new travel options for you and eliminate worries about running out of power when on a long trip or during storage.

For more, pick up your copy of Rich Luhr’s books, “The Newbies Guide To Airstreaming” and “Airstream Life’s (Nearly) Complete Guide To Airstream Maintenance” at the Airstream Life store.

Questions and answers about power, batteries, and solar

Solar power, shore power, generator backup…the configurations are as varied as the number of rigs on the road, and the answer to most power questions is “it depends”.

While each Airstream is uniquely outfitted, many Airstreamers have common queries. Following are answers to questions posed at one of our recent Aluma-events.

I’m a solar user, but what happens to my batteries when I plug in to shore power?

Your solar panels are still active when you use shore power, and a built-in regulator prevents the batteries from overcharging. Put simply, solar panels always produce power when exposed to light, and that power is sent to be stored in the battery. Shore power (AC, which gets converted to DC) also goes to the battery, so both sources are working to keep the batteries charged. One source might contribute more than the other, but it’s all good power input.

How can I extend my battery life?

Baby it. Your battery will last nine years and counting, depending on how it’s maintained. If you’re plugged in often, it’s a good practice to check the battery water every 30 days. Pop the caps off and fill them up over the lead plates; otherwise, they’ll sulfate and corrode the other batteries.  A dead cell in one battery will drag the other battery down with it, over time.

If it freezes outside in winter it won’t last it’s full life expectancy. Don’t leave it dead; if the electrolytes aren’t excited in the battery, they’ll freeze. Take your battery out and let it winter over in the garage.

Can my family multitask in the trailer?

Yes, but to a reasonable limit. If you’re using a curling iron, the air conditioner, and a microwave all at the same time, you’ll draw too much and flip the breaker. Overloading the outlets (a.k.a. AC power system) with too many plug-in appliances will trip the circuit breaker.

DC power differs, and if your battery has drawn down too low you’ll have trouble with the vent fan, lights, or water pump—and there’s no circuit breaker on the DC power system. When lights dim and the pump and fan are sluggish (or non-working), it’s past time to recharge. Try not to draw the batteries down more than 50% between charges, because doing so will shorten its life. Consider installing an amp-hour meter to more accurately keep track of the power in your batteries.

Where is my converter? And what does it do?

Your converter changes 120 volts AC shore power to Airstream appliance-friendly 12 volt DC power, and prevents your Airstream battery from draining. You’ll have to snoop around to find it, as the location depends on your Airstream floor plan. Often the power converter (a “black box”, literally) will be installed under the refrigerator or sofa, or inside the closet. Open the door and you’ll see the 110 breakers and fuses inside.

I want to go solar. How much do I really need? How much does it cost?

These and other questions about solar conversion are like asking “how long is a rope?” Answers will vary, depending on the panel size and watt capacity. Some users claim that one hundred watts of solar provides enough power for a family; others require nearly three times that amount.

Your location and weather play an important factor as well, as the battery charges through the day for the night, and recharges the next day—and the more panels you have, the merrier you’ll be. The number of permanently-attached solar panels you can accommodate depends on your Airstream model and the available real estate on the roof.

What’s that rotten egg smell?

Could be the converter is overcharging the battery, but more likely you have a battery low on water (assuming it uses water). Allow the battery to cool before adding more water.