Author"s Notes:I am a experienced renewable energy (RE) author and avid flyfisherman, and also I"ve lived 12 miles off the power grid for the last 15 years, powering my home entirely from solar and wind power. I get a ton of email each week with inquiries around the basics of designing RE power systems, ranging from tiny units for a camper trailer to large home power systems. This post is my attempt to describe the basics of it for a complete beginner. Hopecompletely I"ve removed most of the jargon, and at leastern defined all the jargon that"s offered.

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Yep, that"s a ring from a increasing trout in the reduced righthand corner! We recorded and also released over 200 trout on that 2-day camping trip. It was the shakedown cruise for our new old pop-up camper and its brand-new solar power mechanism. The device operated great!


Our vintage 1968 Starcraft pop-up camping trailer, the "Sally Ann."

Unfortunately for his employers at, DanF is a trout bum. That implies that at particular times of the year, he is "unavailable" for occupational because of a particularly nice insect hatch on our house waters here in Northern Coloraexecute, or indeed anytime all his hrs invested staring at a computer display screen start turning his brain into mush and also making his eyes go googly.

DanF"s employers, who are more than likely now reading this new internet page, are especially advised to note how often this problem occurs. He apologizes sincerely to them for trying to convince them last fall that our agency web server cluster facility was located on the shores of Hohnholz Lakes on the Laramie river for better security, and also that weekly trips up tbelow were required for regular servicing. In truth, our servers are situated alengthy the North Platte river in the stretch in between Seminoe Resevoir and Pathfinder Resevoir in Wyoming, often dubbed the "Miracle Mile."

According to the finest clinical research study available, the just sure cure for these exhaustion and "googly eye" afflictions is a few days of fishing. Because DanF"s Dad has a vintage 1968 Starcraft pop-up camping trailer easily accessible for usage, DanF figured that installing a basic solar power device in the "Sally Ann" and writing a internet web page about it would be an excellent way to capture the late summer damselfly hatch near Walden, Coloraexecute and also the October caddis hatch in Lowell, Idaho and also still pretend that he was actually functioning the totality time!

System architecture considerations

(and also just how we addressed them)

How much power execute we really need?Not a entirety lot for us--we go camping so we can flyfish, and obtain amethod from all the contemporary contraptions and also their noise. We require lights at night, a portable radio / CD boombox, and also battery chargers for our 2-means radios, digital cameras, and also GPS devices. Bideal lights are vital if we are tying trout flies in the evenings. If we carry our vintage Grumguy canoe, we do usage some significant power via the electrical trolling motor--even more on that later.

Tright here have been various other civilization at certain campgrounds we"ve stayed at recently that seem to require satellite tv dishes, substantial screen TVs, electric Mister Coffee devices, electrical refrigerators, and all kinds of other stuff that we are trying to acquire ameans from. They put all this stuff right in their campers! We are boggled by this perspective in the direction of wasteful power usage, and also the noise, fuel price, and also maintenance components of running an infernal combustion engine at the edge of the wilderness. Perhaps we are Luddites, but we carry out like our peace and also quiet. That"s why the "Sally Ann" is powered only by (silent) solar power, with the alternative of a (again, silent) shore power connection.

12 volt DC versus 120 volt AC power systemsA few years ago, just about everyone that powered a camper (or little cabin, for that matter) from solar provided a 12 volt DC (12 VDC) system--that"s a straight feed to your cigarette-lighter-plug devices off of a 12 V battery or bank of batteries. Problem is, 12 volt power has numerous losses in the transmission, and to minimize the losses points have to be wired with incredibly thick, expensive wire that"s difficult to work with. That"s why the majority of 12 VDC lights and also appliances are incredibly little...a typical car cigarette lighter plug and outlet can not handle a lot power prior to coming to be warm from electric resistance and also melting your dashboard, or (hopefully) blowing the fusage first.

In the last 5 years, "power inverters" have dropped substantially in price and become commonly available--the internet, truck stops, the neighborhood NAPA auto components shop, everyone sells these tools currently for cheap. Many are approximately $150 or much less. They transform 12 volt DC power right into 120 volt AC power, additionally recognized as "house present." That"s what"s accessible at eexceptionally electric outlet in your home in town! If you are not in the USA, inverters are obtainable global for every different electric system, you simply have to buy the best one for your nation. With an inverter, instead of buying all brand-new light bulbs, boom boxes, toasters, radio/GPS/video camera battery chargers and such for your 12-volt camper, you can usage the stuff you already have, or buy new ones from K-Mart for cheap. A typical (and also highly efficient) compact fluorescent (CF) light bulb for 120 volt AC house existing will certainly cost you only a pair bucks at Home Depot or the local superindustry. A 12 volt DC variation will expense you at leastern $10 per light bulb, be obtainable only digital or at a specialty RV shop, and also probably will not be constructed by a significant US or European manufacturer from whom you deserve to obtain a remoney if it doesn"t job-related right.

We chose to go via 120 volt AC inverter power for the Sally Ann. A quick trip to K-Mart, and all our lighting and also appliance requirements were met at low price. Buying all those devices aacquire for 12 volts DC would certainly have actually cost far even more than the expense of the inverter! We finished up with a 1500 watt Whistler inverter, much even more than we need, however it was easily accessible cheaply provided. If we were to actually RUN a 1500 watt pack from it, our bit marine deep cycle battery would be dead in less than an hour. To pick the correct size of inverter, total up the power draw in watts for all the lights, appliances, and also various other devices that you could be running all at the exact same time, and also pick an inverter via a "continuous" power output of a couple hundred watts above that. "Surge" power output that"s advertised is not a beneficial spec--if you ever reach this number in the power you are utilizing, your inverter is also little. Also, be sure to follow the inverter manufacturer"s references for wire dimension from your battery to the inverter--this wire demands to be both thick and also versatile.


1500 Watt Whistler inverter mounted under counter, to keep it safe from water drips, bourbon and beer botches, chili spills, and tipsy flyanglers.

Power versus Work versus EnergyFolks regularly acquire confused around the correct systems in which to meacertain power intake. Watts measure power being offered or gained at any type of provided prompt. But Energy is what"s a lot of vital to you, not power-- Energy is power measured over time. It does not issue that the massive TV in your camper offers 200 watts. The real concern is just how many type of hrs per day you have actually the thing on! So, the correct devices to use are watt-hours or amp-hrs (A/H), not watts or amps. Ten amp-hrs of usage suggests that you ran your boombox that draws one amp for 10 hours--or that you ran your massive TV that draws 10 amps for one hour. You get the concept.

Appliances and lights are constantly rated in watts, and also they are always marked on the earlier for how many watts they draw at full power. Batteries are rated in amp-hours of capacity. The just math you should execute for making a straightforward RE device is converting watts to amps. Then you multiply by time to acquire amp-hrs. Watts = amps x volts, and also amps = watts / volts. So, a 60 watt light bulb powered from your inverter will usage 1/2 amp at 120 volts AC (60 watts / 120 volts = 0.5 amps). But your battery is 12 volts! So to power this bulb, you should do the math for what"s really coming out of your 12 volt battery-- 60 watts / 12 volts = 5 amps.

Choosing the batteryThe Trojan CB-27 battery we mounted in the Sally Ann stores 100 amp-hrs of power. BUT you never, ever desire to take any battery down below 50% of its capacity--most batteries have the right to just do this for you a pair dozen times, then they are damaged. For lengthy battery life (2 years or more) don"t take your battery down by more than 30% of capacity. If you have the right to afford to relocation your battery every year or two, you have the right to be even more abusive.

The 30% discharge pointer states we deserve to frequently attract dvery own the battery on the Sally Ann by 30 amp-hrs, through occasional drops to 50 A/H (half capacity). So, for decent battery life we can run that substantial 60 watt light bulb for at most 10 hrs to take our battery dvery own to half capacity (100 amp-hrs / 5 amps = 10 hrs.) If we ran our cute little 1000 watt electrical heater from inverter power, the math would be: 1000 watts / 12 volts = 83 amps-- a bit over fifty percent an hour to the "battery critical" condition of 50% discharge. Cold Cranking Amp (CCA) ratings on batteries are useless for measuring storage capacity. CCA is for automobile engine founding batteries, not RE devices. The number you should look at is amp-hours (A/H). You might need to ask your battery dealer for this information--it might not be printed on the battery.

You have the right to combine multiple batteries for more capacity, if you have the space. Standard "marine deep cycle" batteries are a great alternative for a tiny mechanism, they withstand also deeper discharge a lot better than automobile engine founding batteries. For a larger camper or a cabin, you can think about golf cart batteries (T-105s), which need to be mounted in pairs because they are 6 volt, not 12 volt. Home or cabin power units frequently use 6 volt L-16 batteries, which have actually several capacity and also are extremely durable--however they are large, hefty and also expensive, and commonly a lot more than can be fit right into a camper. So-referred to as "gel cell" batteries have actually the benefit that they have the right to be tipped over without shedding electrolyte, however in basic they are a lot more expensive and fragile than the run-of-the-mill "flooded lead acid" battery we offered in the Sally Ann.


Trojan CB-27 battery in the battery box, through lid rerelocated. Inverter is mounted over it. 100 amp-hours capacity. Note how thick the inverter wires are -- this is vital. The battery box is screwed to the floor so that nothing have the right to relocate.

Lighting choicesA 60 watt incandescent light bulb wastes more power as warm than it turns right into light. Think of any incandescent bulb as a space heater that produces light as a byproduct! Fluorescents (FL) and also compact fluorescents (CFs) are FAR more reliable, and also they have to be the only bulbs you even take into consideration for an RE power mechanism. LEDs are additionally an option--they are not extremely reliable (despite many kind of heralding claims), but they perform emit many of their light in one direction, eliminating the require for reflectors. Our lights are a pair of 7 watt compact fluorescent (CF) bulbs, plus a CF fly tying lamp that uses 13 watts, for a full of 27 watts with all lights on. That"s 2.25 amps at 12 volts, so we could then run all these bulbs at the exact same time for 13 hrs without damaging the battery (30 amp-hrs / 2.25 amps = 13.3 hours.)

The solar panelWe didn"t want any type of glass in our solar panel bereason of lengthy drives on bone-jarring dirt roadways, so that ruled out all the normal models intended to be placed on homes. My remote residence in the hills runs on such solar panels, yet we feared breakage throughout our driving. We additionally did not want to permanantly mount the panel to the roof of the trailer--we"re lucky the old girl does not already have a leaky roof, and placing holes in it sounded favor a negative idea. Plus, a flat mounted solar panel does not do a lot excellent unless you are close to the equator--for maximum power generation, solar panels should be dealing with straight at the sunlight.

There are some really cool flexible solar panels available--you can roll them up for storage, and also mount them on the upper deck of boat and also walk on them--however they are much even more expensive than typical models. For solar panels, it all boils down to dollars per watt. Standard, "single-crystalline" or "poly-crystalline" panels mounted under glass for dwellings run around $5 per watt ideal now. "Amorphous" panels are up about $6-8 per watt, and versatile amorphous panels deserve to reach $10-12 per watt! Amorphous panels have actually the disbenefit of making a lot less power per square foot than single or poly crystal, but have actually the benefits of not being so brittle and vulnerable, can be constructed into versatile panels, and also are affected less by partial shading.

We couldn"t see the logic in paying more for one versatile, roll-up solar panel than what the pop-up camper cost us in the initially place! So, we compromised--our solar panel, made by Innergy and also largely provided in remote river gauging stations and also other telemeattempt applications, supplies single crystal cells installed in fiberglass rather of under breakable genuine glass. It provides 30 watts of power in full sunlight, and also is just 19" x 36". It came in at $5.97 per watt, a lot better than roll-up models, and also it provides more power for its dimension than amorphous designs. We developed a straightforward aluminum structure for it that we deserve to prop up close to the camper after we arrive at a remote campsite. Shading is a huge aspect in solar panel output, even one branch shading component of a solar panel reduces output to virtually nopoint. With the 25 foot extension cord, we can put the camper in a shady spot and also set the panel in the sunlight.


Our glass-less, fiberglass embedded solar panel through homeconstructed aluminum structure. The tree shading presented in the image is BAD--the panel is hardly putting out any power bereason of the shading.

Solar panel wire sizingRemember that we debated earlier how tough 12 volt DC power is to relocate approximately compared to home current? Ideal wire thickness is important in connecting solar panels or else much of the power coming in will certainly be shed as heat (just prefer in a toaster, just the solar panel wire won"t even feel warm to the touch.) Wire losses of around 5% of your panel"s output are acceptable. Rather then go into all the math, the simplest method to perform it is Google up "wire size chart" digital, or acquire a published one from any large renewable energy dealer"s catalog. Ssuggest look up your panel"s output in amps at 12 volts, and also review the maximum distance you have the right to go on certain gauge of wire. Exstress cords are good for this, however be sure to check on the package what the actual wire dimension inside the cord is. Usually, 10 or 12 gauge is the biggest accessible at the hardware keep...gain the ideal and also thickest you deserve to afford. The more power your panel puts out, the thicker the wire you need and also the shorter the distance you can go. For us, a nice 25 foot, 10 gauge extension cord cost about $25 and has exceptionally little bit loss at just 2.5 amps from our solar panel--we might add a pair even more solar panels later on and still have the ability to usage this cord through under 5% loss.

Solar panel controllersLarge home-sized solar power devices constantly have actually controllers to keep the battery financial institution from overcharging. In our tiny device, we did not encompass a controller. The factor is that traditional "flooded lead-acid" batteries are not damaged at all by "overcharging" -- identified as continuing to pump electricity right into the battery after it"s full. All that happens is that the battery electrolyte level drops more rapidly as the battery bubbles. If the electrolyte level drops below the peak of the plates, the battery is destroyed. It"s important in any type of RE power mechanism, via a controller or without, to examine the battery electrolyte level monthly and also refill it with distilled water once it gets low. In our case -- we"ll never have that battery bubbling on a fishing pilgrimage, we usage as well a lot power eextremely night. When the trailer is parked at house waiting for the following pilgrimage, we plug in the solar panel for a day or 2 each week to store the battery topped off. If your battery is bubbling, it"s no problem -- however do not smoke around it, and also be sure the hydrogen is appropriately vented to the external. In a camping trailer power system, the only time the battery can be bubbling is when the trailer is in storage for the winter with no power intake. If you for some factor determined a gel cell battery, a controller is REQUIRED, and will certainly expense you $50-100.

Back to input vs outputWe just did all that math around just how much you can draw dvery own a battery. Now look at our input from the solar panel (30 watts, 2.5 amps) versus the output from our lights (27 watts, 2.25 amps.) Here in Northern Colorado, a good clear day gives an average of around 6-9 full sun hrs on a panel, it varies significantly by season. Multiply that by the amps output of the panel to figure just how many kind of amp-hours are coming in. 30 watts = 2.25 amps x 6 hrs = 13.5 amp-hrs (winter), and for 9 hrs of solar exposure (summer) it"s 20.25 amp-hours. That"s not too bad--we could run our 27 watts of lights for 6-9 hrs at night after a sunny day. What if it"s overcast, or rainy? Solar panels put out nearly nopoint unmuch less they are in full sun. After a few cloudy days, we"d be dipping deep into the batteries capacity to run our lights for 6 hours a night. That"s where shore power have the right to be handy!

Renewable energy versus shore power

In a home in tvery own, you"d speak to it "grid power" instead of "shore power." It"s your fundamental electrical outlet right into which you deserve to plug your camper electrical device. Most campsites that administer shore power additionally administer shore water pressure. This is absolutely worth the tiny amount of money it prices per night! Besides having actually safe and clean water under pressure hooked best right into the trailer, an easy 10 amp battery charger from the auto components save can be running at any type of time we are connected to shore power -- that 10 amps coming in is choose having actually 4 of our 30 watt solar panels running at when. Even so, the cute little bit 1000 watt electric heater we carry alengthy to warmth up the camper while making early-morning coffee is ssuggest NOT feasible to run off of a renewable power mechanism, no issue exactly how many kind of solar panels and batteries were installed. We run it off of shore power just. It"s the same in town--electric ranges, water heaters, room heaters and also such use much more power than even a large renewable power mechanism can administer.

Is a transport switch needed?

All a deliver switch does is switch your electric outallows from shore power to inverter power and earlier aget. Some are automatic, some are hands-on. All are expensive. To save money, we simply wired up a pair of outallows in the Sally Ann--one is for shore power (if it"s available) and one is for inverter power. Simple, cheap, and deserve to cause no confusion if effectively labelled. The only thing an incompetent operator would have to remember is to NOT plug the 1000 watt electric heater right into the inverter output--shore power only for that power hog of a (exceptionally handy) gadget!

I currently have actually a generator, will certainly it help?

You bet! In a remote campsite wright here there"s no shore power, a generator can be really handy. And the battery mechanism suggests that you can not need to run your generator late at night to watch TV--you might instead boost your battery through the generator throughout the day, and also store a silent campground at night by running your TV off of the inverter. In our instance we"d ssuggest plug the generator into our shore power input, and both run tons directly from it, and use the staying generator power to charge our battery through the standard NAPA battery charger we haul together with us. Get the best battery charger your generator have the right to take care of and also that you can afford. Generators offer you the most watt-hours per gallon of gas when you run them at 50% of their rated pack or even more, and run time will be much less to fill your battery once utilizing a large charger.

How around water pressure?

Once aobtain, we preserved it straightforward. There was currently a typical camper-style water faucet over the sink in our camper. If there"s shore water pressure available, we push dvery own on the handle to gain water. If we are utilizing water from our self-had water cistern (a brand-new, clean, food-grade, white 5-gallon bucket) we pump manually from it via the same take care of. An electric water pump would certainly have been an alternative, yet adds more electrical power use and feasible relicapacity difficulties to the water system. It would be irritating to be without water just bereason the battery was low, through no sun or shore power to charge it back up.

What around the trolling motor?

On some lake fishing trips, we bring our vintage Grumguy canoe and also small electric trolling motor along. It"s simple to drain that battery method dvery own through simply a few hrs of flyfishing, especially in windy conditions. So, we determined exactly the exact same battery for the trolling motor as we did for the trailer -- they fit in the exact same battery box and hook up the exact same method, so we deserve to conveniently exreadjust the trailer battery for the troller. Shore power via a battery charger or a straight connection to the solar panel are the ideal ways to charge up the trolling motor battery. Don"t try to run your 120 vac battery charger from the inverter to charge the trolling battery! You"d be converting 12 vdc to 120 vac ago to 12 vdc for charging, with losses eexceptionally action of the method. It"s much more efficient to charge the trolling battery from shore power or direct solar...that"s the primary factor we made it straightforward to swap batteries in between the canoe and also the camper.

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You could spend lots and also several money on a solar power mechanism for a camper. In reality, I wish some of those folks via noisy generators on our last fishing trip had actually done so! The trouble is, they would HAVE to spfinish a lot of cash to run all those power-hogging tools off of solar. The very same trouble crops up in developing a renewable power device for a home or cabin--the even more kilowatt-hours of power you usage each day, the more batteries and solar panels you need. Conservation is the key--it"s estimated that for eextremely dollar you spend on energy conservation, you conserve $3-5 on the expense of the RE devices required to power your stuff. If we"d used incandescent light bulbs in the Sally Ann, our possible run time prior to the battery was empty would certainly be around 6 times less! The very same for TVs, computer systems and anything else you need to run in the backcountry. LCD display screen TVs have exceptionally low power draw compared to normal models, as do lappeak computers. Use an old-fashioned stove-top toaster instead of an electrical one. Install a propane fridge instead of an electrical one. Pick which appliances you usage on a expedition, depending upon whether you are hooked right into shore power or not. The electric toaster oven is FINE on shore power, yet not on solar! Microwave ovens are surpclimbing --- they usage several power (800-1500 watts) however are just on for a minute or 2, so a little microwave is perfectly feasible on solar power.

The vital to using renewable energy, and also one good advantage, is that you MUST be aware of your power consumption at all times! When you rerevolve residence, you"ll suddenly be aware of all the power you are wasting every day. You might also turn right into a "power ogre" prefer me, roaming the house finding TVs and lights that were left on and also shutting them off!