Rationing solar power is cheaper and easier than making more power, especially when you are making solar power with the limited roof space of a vehicle. Any electricity you can save, especially during periods of low solar harvest, means you have to worry less about generating more electricity.
Causes of inadequate solar harvest
Sometimes normal awareness is not enough to keep a solar setup functioning with usable power. In these situations one might need to take steps to minimize loads and maximize power generation. What can cause inadequate solar harvest?
- smaller solar installations
- a stretch of rainy days
- a forest campsite with no good access to sunlight
- smoke from forest fires
- very short winter days
Minimizing loads
There are many strategies to reduce your electric loads. Tackle your biggest power draws first, and then look for ways to reduce power that won't reduce your comfort or convenience.
It's very expensive to generate heat with electricity, usually for the purpose of keeping warm or cooking. Switch to other methods if you can. For example, cook with propane on a camping stove instead. If you have an electric space heater, switch to contact warming options instead.
Inverters change the DC power from your electrical system to AC power for use by things like household appliances. The inverter itself uses power. Some strategies to reduce inverter electrical waste:
- Minimize the use of inverters by using 12v appliances and adapters when possible.
- Turn inverters off when not in use.
- Size the inverter to meet the needs of your biggest loads. Oversizing wastes power because bigger inverters have more parasitic draw. It may be worthwhile to have a small inverter for small loads and a big inverter for big loads; this stops the inefficient use of small loads on a big inverter.
- Choose a Modified Sine Wave inverter for appliances that don't require Pure Sine Wave power. MSW inverters have lower parasitic draws.
Other strategies to minimize loads:
- Find and eliminate parasitic loads.
- Make it a habit to turn off anything you don't need right now.
- Wait until you have excess power to recharge phones, laptops, portable power stations, etc., or look for places to recharge devices.
- Go to bed with the sun, rise with the sun.
- Use low-power entertainment like reading instead of power-hungry entertainment like TV, gaming console, etc.
- Turn down screen brightness on phones, tablets, TVs.
- Open your refrigerator as little as possible after sundown
Maximizing solar harvest
Be aware of the shade impact on your solar harvest, which can be significant even if your panels are only partially shaded. Ensure the panels are not shaded by natural and nearby obstructions (trees, overhangs, buildings, etc.) or by obstructions on your own vehicle (antennas, A/C units, roof vents, etc.). Park so that the greatest expanse of panel is facing south and any obstructions are on the north side of the van.
Consider tilted solar panels or side-mounted solar panels if possible to increase your harvest when the sun is not directly overhead.
Keep your solar panels cool when possible; panel output drops as cell temperature rises. Ensure that no tarps, awnings or other obstructions are preventing cooling breezes from passing under/over the panels. Framed panels should be mounted with some space underneath them for cooling airflow.
Keep your solar panels clean. Dust or dirt on the panels can decrease panel output by 5-10% in some cases.[1]
If you have a PWM controller, tweak it to produce more power, and be ruthless about not running loads until the battery bank is out of bulk mode.
If you have an MPPT controller, configure it to battery manufacturer specifications.More …Other strategies
Use shore power charging (via converter) anytime it is available. Install a battery isolator for alternator charging.