Powering an Off-Grid Lakeside RV: Solar in the Forest Shade

Read the full article: Powering an Off-Grid Lakeside RV: Solar in the Forest Shade

Discover more at Boondocking Tips

Excerpt:

Powering an Off-Grid Lakeside RV: Solar in the Forest Shade

Camping by a quiet lake under a cathedral of trees is a dream – until you realize your solar panels barely see the sun. Dense tree canopy and morning fog can cut incident sunlight dramatically, forcing boondockers to rethink their solar setup. By understanding how shade and diffuse light affect PV output, and by planning smart panel placement and battery storage, even a shaded lakeside RV can achieve reliable off-grid power. This guide analyzes solar harvest under forest canopy, compares fixed rooftop vs portable panels, and covers tilt, water reflections, battery choices, load planning, and safety for an off-grid RV in a humid, lakeside setting.

... Continue reading

Transcript

SPEAKER_00 0:00

Powering an off-grid lakeside RV, solar in the forest shade camping by a quiet lake under a cathedral of trees is a dream. Until you realize your solar panels barely see the sun. Dense tree canopy and morning fog can cut incident sunlight dramatically, forcing boondockers to rethink their solar setup. By understanding how shade and diffuse light affect PV output, and by planning smart panel placement and battery storage, even a shaded lakeside RV can achieve reliable off-grid power. This guide analyzes solar harvest under forest canopy, compares fixed rooftop versus portable panels, and covers tilt, water reflections, battery choices, load planning, and safety for an off-grid RV in a humid lakeside setting. Solar harvest under forest canopy. In a forested lakeside campsite, shade and fog are the enemies of solar generation. Tree cover intercepts direct sunlight, and low clouds or mist scatter it. Although solar panels can still produce under cloud cover, output is much lower. One PV blog notes that on overcast or foggy days, panels may yield only 10 to 25% of their clear sky output. In heavy morning fog or thick tree shade, plan on roughly a quarter of your panel's rated power. Shade is especially pernicious because a single darkened cell strings can drag down the whole panel. Studies of residential PV systems show significant power loss even with partial canopy shading. One review found that a relatively small shaded area, e.g. 20% shade, leads to noticeable dips in daily energy yield. In practice, expect overall insulation under dense forest canopy to be far below open sky values. A U.S. Forest Service primer on Solar and Woods notes that sunlight under trees follows an exponential drop-off, with direct sun nearly zero and only diffuse light reaching the understory. In broad terms, a sunny midsummer day at noon, 1000 W meters square direct, might translate to only a few hundred W meters square diffuse light in deep shade. However, even scattered daylight adds up. PV cells respond to diffuse photons, so you'll get some current. In fact, panels make some power in low light, roughly 10 to 25% of peak, according to one manufacturer's guide. To quantify your expected yield, it helps to monitor a sample day's output once on site. For modeling, assume that bright sun hours, peak noon, are cut in half or more after dawn until the canopy opens. For example, if an open-air 200W panel yields about 1 kilowatt hour per day at this location, under forest shade, you might only get 300 to 500 watt hours per day. Actionable tip. If possible, cite your RV and panels where the canopy opens up by late morning. Sometimes roads or clearings at Lake Edge have less shade. Even a few extra hours of sun above the trees can double your generation. Portable panels can be moved to sunlit spots, fixed roof versus portable ground panels. For an RV, solar panels are often roof-mounted or portable ground, or a mix of both. Each has trade-offs. A recent analysis found that despite a portable panel's convenience, fixed panels generally outproduce them. A 100-watt portable module at typical 18 to 22% efficiency often delivers only 80 to 90 watts peak because it lies flat and heats up, yielding about 0.4 to 0.45 kilowatt hours per day under strong sun. In contrast, a 400-watt fixed tilted panel runs nearer 360 to 380 watts peak, delivering about 1.6 to 1.8 kilowatt hours per day under optimal conditions. That's roughly four times the daily energy for four times the panel area, thanks to better orientation, cooling, and higher efficiency cells. Why the disparity? Portable panels heat up quickly and are hard to keep perfectly aimed. The study noted portable panels can reach 65 to 75 degrees Celsius on a 25-degree temperature day, whereas a ventilated roof panel stays closer to 45 to 55 degrees Celsius. Each degree of extra heat cuts efficiency by 0.4 to 0.5%. Portables also usually sit flat, missing roughly 15 to 20% of sunlight versus a tilted panel. By contrast, fixed arrays can be angled toward the sun and benefit from backside cooling and even higher grade monocrystalline cells. All told, the fixed panels yield was measured at about 87% of nameplate versus only around 45 to 90% for the portable, depending on conditions. MPPT charge controllers. Whether fixed or portable, use an NPPT maximum powerpoint tracking controller. MPPTs dynamically adjust to extract peak wattage from panels under changing light. This is crucial under partial shade or fog. NPPT will find the sweet spots in the IV curve that produce the best power. In practice, an MPPT charger starting at 12 to 16 volts input can harvest far more than a simple PWM regulator would. For example, if morning haze provides only diffuse light, MPPT can still capture whatever current is available. Whereas non-MPPT systems risk logging constant partial charge that can damage lead batteries, sulfation. Portable versus panel count. It's common to supplement a small roof array with one or two portable foldable panels. This can significantly increase total power on sunny days. For instance, adding a 100-watt portable in direct sun set up manually each morning effectively adds about 0.4 to 0.5 kilowatt hours per day extra. If your roof only has 200 watts installed, this easy addition can boost daily harvest by 50%. The key is placement. Move the portable into full sun each day. Keep it tilted with a stand and avoid local shade, like parked vehicles or trees. Panel placement and tilt. Water, glare, and albedo. Near water. Placing panels lakeside can have benefits. Open water acts like a reflective surface, especially at low sun angles. A still lake can reflect up to 10 to 90% of early or late sunlight, glinting effect, depending on sun altitude. This frresnal reflection can boost a panel's rear or side illumination. In practice, casual studies of bifacial, double-sided modules show that typical ground reflectivity, around 10 to 15% for grass, adds about 5-8% more energy on the backside. Lake water reflectivity at midday is moderate, roughly similar to dark soil, but at sunrise or sunset it spikes. Thus a panel on the shore might get a small percentage gain from water albedo, although most monofacial panels see little rear side light. Tilt angle. Fixed and portable panels both benefit from tilting. The ideal tilt depends on latitude and season. Roughly equal to the latitude is a common rule of thumb. Many RV boondockers leave panels flat in summer. One guide notes that across most of the US, you can leave panels flat during summer and still receive plenty of solar energy. However, tilting toward the sun, even seasonally, can boost charge. For example, a simple rule for winter is tilt roughly equal to latitude times 0.9 plus 24 degrees. For a 40-degree north latitude campsite in winter, that works out to about 60 degrees tilt, which packs more winter sun onto the module. A tilt stand, or L bracket, lets you adjust panels daily or seasonally. Even a small tilt helps keep panels clean. Near a lake, pollen, dirt, or bird droppings can stick to flat panels. An angle of at least 10 to 15 degrees allows most rain to rinse debris off. In high humidity camps by forests or water, keeping panels angled also reduces stagnant water pooling, which can scratch or leak. Glare and orientation. At a lakeside RV park, you may worry about blinding neighbors or boaters with reflected light. In practice, solar panel antireflective coatings and typical tilt send most light upwards, above eye level, during daylight. The worst glare is around sunrise/slash sunset, when you can simply adjust panel orientation away from heavily trafficked angles. It's wise to position panels so they don't directly face roads or nearby cabins. A general tip: park your RV so the panels face south in the northern hemisphere when you settle for the day. One RV guide stresses orienting the RV so the solar side is southward from maximum daily sun. It even suggests parking curbside facing south if your fridge is on the street side. That way the fridge stays northward cooler and panels face true south. Whenever possible, position panels to avoid morning shade and to maximize their southern exposure. Battery choices LAFE PO4 versus AGM in humid conditions. Choosing the right battery chemistry is critical for lakeside reliability. LAFE PO4, lithium iron phosphate batteries have become popular for off-grid, but AGM absorbent glass mat lead acid are still common. In humid or marine-like environments, LAFE PO4 generally outperforms AGM in longevity and moisture tolerance. Key differences cycle life and usable capacity. LATHE PO4 can often endure 2,000 to 5,000 cycles, life measured to 80% capacity, whereas AGM is typically limited to 300 to 500 cycles. Moreover, a 100 amp hour lathe PO4 battery can use nearly 100% of its capacity safely, about 12.8 volts nominal, whereas AGM should only be drawn to about 50% depth of discharge to avoid sulfation. In practice, this means one 100 amp hour lathe P04, about 1200 watt hours usable, replaces roughly two 100 amp hour AGMs, which only yield about 600 watt hours usable. Detailed comparisons show LATHE PL4 delivers two times to three times the usable energy for similar amp hour ratings, making it more compact and lightweight. Roughly one half weight for same usable energy. Humidity corrosion. LATHE PO4 cells are sealed, usually IP54-IP67 rated, and do not off-gas in normal operation, so they handle humid air and tilt well. In fact, a recent battery comparison notes LAFE PO4 units are often IP67 sealed and saltwater ready for marine use. By contrast, AGNs, while sealed, still vent tiny amounts of hydrogen-oxygen when overcharged, and their fiberglass mat can harbor moisture. High humidity accelerates lead acid corrosion. A moisture study rated LAFE P04 batteries as having very high moisture tolerance, while AGMs only medium. The biggest risk for LAFE PO4 in dab camps is corrosion of its metal housing. Aluminum cases can oxidize. Whereas for AGM, the risk is surface leakage currents and lead plate corrosion, green oxide forming on posts. In practice, LAFE PL4 terminals and bus bars should still be inspected and coated, e.g., with petroleum jelly to prevent corrosion, but they will far outlast an AGM in a muggy lakeside climate. Charging behavior. LATHE PO4 charges faster, often 2-3 hours for full charge with an MPPT, with about 95 to 98% efficiency compared to AGM, 9 6 to 8 hours, 80 to 85%. Importantly, lathe P04 accepts partial charging without harm, whereas leaving an AGM only partially charged, common in short sundays, causes sulfation that degrades it. If you expect gray, foggy mornings and only hit full sun a few hours at midday, lathe P04's forgiving charging will keep it healthier. Do note, lathe P04 must not be charged below freezing without special care. But if you're lakeside in summer, that likely isn't a concern. Both battery types must be fused and mounted securely. LAFE P04 has very low risk of thermal runaway. It's a very stable chemistry. AGMs have a risk of hydrogen gas when overcharging. Make sure AGM boxes are vented if tightly enclosed. LAFE P04 usually include a built-in battery management system, BMS, that protects against overvoltage, overcurrent, and low temperature charging. Still, both should be secured to prevent tipping in a rolling RV, and terminals should be covered or insulated. Given the moist lakeside, LAFE P04 is generally the better choice for durable, maintenance-free storage. It is heavier on initial cost, about 2 to 3 times the $mh of AGM, but amortizes that with long life. AGM may suit if budget is very tight and use is extremely light and infrequent. If using AGM, plan to coat terminals with anti-corrosion spray and check water levels if flooded type often, as humidity accelerates self-discharge and decay. Load planning and autonomy. Avoid surprises by doing a load audit. Make a simple chart of every appliance's wattage, usage hours, and daily energy need. For example, refrigerator, 12 volt compressor. Modern 50 to 60 liter 12 volt fridges typically use 0.3 to 0.6 kilowatt hours day. Older absorption fridges or larger units may use up to 1.0 to 1.1 4 kWh day. Ventilation fans. Typical 12-volt fans are 10 to 25 W each. If you run one 25W fan for 8 hours, that's 200 WHF. Water pump, a 12-volt pump, draws 50W at peak. If it runs intermittently, e.g. one hour total per day, that's 50 WHF. LED lights, a 5W LED bulb for 4 hours, 20 HF. But four of those, 80 HF, still minor. Electronics charging. Phones laptops can add 100 to 200 WAPS per day if heavily used. E.g., two laptops for 4H. As an example, a moderate Boondocker's daily tally might be 500 to 800 WAPS. The fridge is usually the single biggest consumer, a 400 to 600 WAPS. Fans and pumps often combine for 200 WAPS. Lights and devices may add another 100 to 200 WAPS. If you heat water or cook off-grid, those are additional loads, often not electric in RVs. With a load audit in hand, compute battery autonomy. Autonomy means how long your battery can sustain loads in zero sun. Use usable battery capacity post-DOD. For instance, a 200AH life APO4, 12.8 V, yields 2560WAPS. At 80% discharge safe, that's 2050WAPS usable. If your load is 700W per day, that battery gives 2.9 days autonomy. To be conservative, plan for 2-3 cloudy days of storage. In practice, sizing 3-5 days of house loads is wise in a foggy forest. For AGM, double those amp hours, since only 50% DOD is safe. Example autonomy. Suppose 700 WAPS per day use, 3 days of autonomy, need 2100 WAPS usable. You could achieve this with 175 HH, Life APO4, 12E, usable 2100 WAPS, or 350 HHA, 12V, exploiting 50%, also 2100 WAPS out of 4200 WAPS total. If weight is a concern and cost allows, LifeAPO4 is far lighter. Remember to include inverter efficiency if using AC loads. A 90% efficient inverter effectively requires 10% more battery energy than your AC meter indicates. Safety, corrosion, and security, corrosion and weatherproofing, lakeside humidity and occasional splashes mean everything must be rugged. Use marine RAID materials where possible. Stainless steel or aluminum racking, galvanic corrosion occurs if dissimilar metals touch. Protect all electrical connections. Use MC4 PV connectors rated IP67 and keep junction boxes elevated or sealed against moisture. For battery banks and controllers, choose boxes that shed water, apply silicone sealant to any bulkhead entries. A thin film of dielectric grease on battery terminals and panel wires can deter corrosion. Inspect all hardware periodically for rust or oxidation. If panels sit on foldable stands, rinse them off if they get sprayed with water or mud. Tilt panels sufficiently so rainwater drains off immediately, at least 15 degrees if practical, to avoid stagnant water and algae growth. Cable sizing. In 12 volt systems, voltage drop is a big concern on long runs. A portable panel placed far from the RV's battery may produce less current if the wire is thin. Use thick gauge cable, e.g. 8AWG or 6mm squared, for any run over a few meters and multi-amp flows. As a rule of thumb, a 10A draw over 10 feet of 12AWG wire yields 3% voltage drop. But double the length or have the gauge and the drop doubles. Many ground mount designs use 6mm squared, 10 AWG, to hold drop under 1 to 2%. Always fuse each string close to the source and never rely on the mounting to ground for return. Use the proper negative ground wire. Lightning and tilt safety. A tilted panel on a roof rack can act like a small lightning target. If a storm is imminent, either lay panels flat or disconnect them. Remove cables or actuate any disconnect switch. Do not touch panels or wiring in a storm. Grounding is complex for portable rigs, but ensure your chassis is properly grounded to minimize potential differences. Never coil cables loosely, risk of inductive kick, and always shut off the system before servicing. Theft prevention. Portable panels are attractive targets. While there's no foolproof solution, you can deter opportunistic theft. One recommendation is to secure panels with a steel cable lock, like a retractable toy lock, threading through the panel's handle and around the RV frame. Some campers suggest placing a fake dog or a remote camera near conspicuous panels and always keeping them in sight if possible. When leaving camp for extended time, stow foldables away in the RV rather than leaving them unattended outside. At night, foldable panels should be secured in storage or locked up. Lastly, mark your panels subtly, engrave your name or license, so any stolen unit can be identified. Conclusion, a forested lakeside setting poses real challenges for solar power. But with smart choices, your RV can sit from the sun even in shade and mist. Use MPPT controllers, position panels for maximum open sky exposure, even moving portables daily, and tilt them for better efficiency and self-cleaning. Exploit any water reflection sensibly and be mindful of glare. Choose Deep Cycle Life PO4 batteries for their long life and humidity resilience, and do a careful load audit to size your battery bank for several cloudy days. Always protect electrical gear from corrosion, properly gauge and fuse cables, and secure portable arrays against theft. With these measures, your RV can enjoy the serenity of the forest and lake, and still keep the lights on after dusk. All links to sources are available in the text version of this article. You can find the full article at boondocking.tips. Thanks for listening. For more research driven boondocking guides, off grid camping tips, RV travel advice, and van life strategies, visit boondocking.tips. That's boondocking.tips for the full written research and new camping updates.