Solar loss check
RV solar tilt and shade calculator
Estimate how much daily solar harvest changes when roof panels are flat, portable panels are aimed, shade cuts across the array, or winter sun lowers the useful charging window.
Solar harvest reality check
Estimate what tilt, shade, dirt, and orientation are costing you.
Panel wattage is only the nameplate. This calculator turns campsite conditions into an adjusted daily harvest before you buy more panels or blame the battery bank.
Array and sun window
Angle, shade, and loss assumptions
Harvest result
The solar loss profile looks manageable
Estimated harvest
1.5 kWh
49% below raw nameplate x sun-hours
Ideal tilt
35deg
23% tilt loss, 0% orientation loss
Recoverable
450 Wh
Potential same-shade gain from better aim
With these assumptions, the array harvests about 1,525Wh per day from a raw 3,000Wh sun-hour window. The effective sun-hours land around 2.5.
Same-shade ideal
2.0 kWh
Same shade and dirt, but ideal tilt and orientation
Unshaded ideal
2.3 kWh
Reference harvest before shade but after dirt and system losses
Shade loss
275 Wh
Estimated daily loss from the entered shade percentage
Angle loss
450 Wh
Estimated daily loss from tilt and orientation
Recommended next move
Use the solar calculator with the adjusted harvest number, then check battery recovery before buying hardware.
Watch-outs
- This is a planning estimate, not a site-specific irradiance model. Nearby trees, panel string layout, controller behavior, clouds, and battery charge taper can move the real number.
- Partial shade can be worse than the entered percentage if one shaded panel drags down a string. Check bypass diodes, series/parallel wiring, and portable-panel placement.
Shareable result
Copy a prefilled URL or planning note for a solar troubleshooting thread, club resource page, or campsite planning checklist.
Field note
If shade is the big loss, more roof watts may not fix the day. A small portable panel in clean sun can beat a larger roof panel under branches.
Prefilled solar-loss scenarios
Start from realistic shade and winter-sun assumptions.
Each scenario opens with solar watts, sun-hours, latitude, season, flat-panel posture, shade, dirt, and system-loss assumptions so you can test whether harvest loss is the real bottleneck.
Short trip baseline
Weekend Couple Starter
Use this when flat panels, winter sun, dirt, or campsite shade may explain low harvest.
Load this profileWorkday-capable profile
Remote Work Desert Week
Use this when flat panels, winter sun, dirt, or campsite shade may explain low harvest.
Load this profileLower-sun profile
Shoulder-Season Forest Camp
Use this when flat panels, winter sun, dirt, or campsite shade may explain low harvest.
Load this profileMore people, faster tanks
Family Dry-Camping Long Weekend
Use this when flat panels, winter sun, dirt, or campsite shade may explain low harvest.
Load this profileLean system profile
Minimal Van or Small Trailer
Use this when flat panels, winter sun, dirt, or campsite shade may explain low harvest.
Load this profileWhy this exists
Solar losses are often a campsite problem, not a gear problem.
The regular solar calculator tells you how many watts you need for the load. This tool asks whether the watts you already have are being cut down by flat winter panels, off-axis portable panels, dust, or shade.
Use this with
RV solar calculator
Use the adjusted harvest number when sizing panels against your real daily loads.
Open next stepRoof solar fit calculator
Use this when the answer may be more roof watts, fewer obstructions, or portable solar.
Open next stepRecharge time calculator
Use this to see whether the adjusted solar harvest refills the battery bank fast enough.
Open next stepTool notes
What the solar tilt and shade result is actually saying
The output is a planning estimate for daily harvest under real campsite conditions. It does not approve a mounting method, but it helps decide whether the next move is aiming, cleaning, moving panels, adding watts, or lowering loads.
Raw sun-hour window
Panel watts are multiplied by peak sun-hours before angle, shade, dirt, and system losses are applied.
Seasonal ideal tilt
The planning tilt uses latitude for spring/fall, latitude plus 15 degrees for winter, and latitude minus 15 degrees for summer.
Adjusted harvest
Tilt mismatch, orientation offset, shade, soiling, and system losses are multiplied together so the result reflects stacked real-world penalties.
Avoid these traps
Common mistakes before buying
Using panel nameplate as daily harvest
A 600W array does not make 600W all day. Sun angle, temperature, wiring, controller behavior, battery taper, and shade reduce the usable number.
Adding panels before fixing shade
If shade is the main loss, more roof wattage can disappoint because the shaded section still drags production down.
Treating flat winter panels like summer panels
Flat roof panels are convenient, but winter sun arrives at a lower angle and the same roof can produce much less than the summer estimate.
Use the result as a solar-harvest adjustment before sizing batteries or buying more panels. Real production still depends on weather, controller behavior, battery state of charge, panel wiring, and campsite shade.See assumptions
Frequently asked
Questions RVers usually ask next.
Is this a replacement for PVWatts?
No. PVWatts or a site-specific solar model is better for location-specific annual production. This tool is meant for RV planning when you need a quick campsite and panel-angle reality check.
Why is orientation ignored for flat panels?
A flat panel does not really face south, east, or west in the same way a tilted panel does. Orientation matters most once the panel is tilted toward a horizon direction.
What should I enter for shade loss?
Use your best estimate of production loss, not just the percent of panel area shaded. Partial shade can be non-linear, so a small shadow across the wrong cells can be worse than it looks.
Should I tilt roof panels?
Only if the gain is worth the setup friction and wind risk. Many travelers leave roof panels flat and use portable panels when winter sun or shade makes aiming worthwhile.