Living Solar On Gloomy Days: How To Charge Solar Lights Without Sun

Let’s accept it: solar is the new future. The scientists declare that a perovskite solar cell is able to help with solving the world energy crisis. Generating clean electricity from the sun turns out to be cheaper day by day, so more homeowners are able to afford it.

I love having solar gadgets all around the house: a bunch of LED-lamps, the security camera, the “eco” power bank and even my mole repellents are solar-powered. Which apparently means I’ll still keep my head above the water in case of an emergency or, for instance, a merciless mole invasion. But am I so right about it?

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The question is whether or not there’s a possibility to charge all my solar devices when there’s no direct sunlight? Those who live in LA, or in New Mexico, or in mid-Arizona, aren’t familiar with such issue. But what about other regions where the sun comes out once in a blue moon? Should we consider an additional spare kit of non-solar appliances for the overcast weather? How to use a solar panel to charge a battery if there was no sun for a long time?

Would you be surprised figuring that the solar panels are still producing watts when it is raining outside or even after the sunset? And yet this is 100% true because they are very sensitive to light. Of course, the amount is tied to the sun exposure, and it’s impossible to get an equal voltage as you obtain from the direct sunlight. But you still can follow a comfortable lifestyle and even save a little on your bills.

Beware of the dark side

So as to always answer “Sure!” to the question “Do your solar panels work on cloudy days?” you need to get prepared in advance, before the installation. Here’s a complete to-do-list for the design phase of any of your solar projects.

• Think of best placement. You’ll get maximum efficiency with the south- or west-facing rooftop. In any other case review your project: it would be better to put your panels onto the ground (or mount them to the wall, or even consider high-tech solar-panel-windows https://www.britesolar.com/products/solar-glass/ or http://www.energyglass.com ) and face directly to the south instead of installing them on any north-facing slope.
• The same advice works for any outdoor solar-powered appliance: make them always watch south! Or, if possible, consider an additional tracker – a platform that changes the direction and the angle of the panel and orients it toward the Sun. A tracking option helps your device follow the day arc so it gets as much direct sunlight as possible. Works best for garden lamps, water fountains and other types of garden or outdoor equipment. It’s already proven that a “tracking” solar panel harvests up to 25-30% more energy than the static one.

Advanced tip. For an experienced DIYer, I suggest building your very own solar tracker. It might be as miniature as shown or as big as you may create. This following tracker works with water bottles and gravity and is easy and very affordable.

The coolest DIY I’ve seen on the web uses freon and a hydraulic cylinder. As freon warms up and expands, it starts to move the cylinder so the head with the solar collector “turns” itself.

Shade is an enemy when it comes to solar energy. While planning where your solar lights or batteries would be located, make sure to avoid any kind of tall objects, buildings or trees. Otherwise, the capacity of your devices is compromised – and, on a rainy day, their effectiveness goes strictly to zero. The easiest way to find out the regular shaded areas is to use mapping tools and solar simulators. Check out these websites before you pick the proper place for your future solar project. They are based on satellite maps, existing photovoltaic installations, irradiance data, so a new customer might measure his household’s solar potential and even estimate the financial benefits.

1. energysage.com
2. geostellar.com
3. sunnumber.com
4. mapdwell.com
5. pvwatts.nrel.gov

Advanced tip. Ask a specialist to conduct a full “solar shade analysis” using a special device called “SunEye”. The magic comes from the fisheye lens of this pocket camera. You just climb to the rooftop, take a picture strictly upwards and figure out whether there are shaded areas around. Also, the build-In software adds the annual sun path to it and shows what time of day and which month the shade might occur.

• Any solar device needs light, not heat! Provide airflow to your rooftop panel or the smallest portable solar power bank. Do not place them directly to the flat surface, think over some kind of rack or rail to put under your appliance. If the convection is blocked, a solar-operated device might overheat and lose its efficiency. So make at least a 3″ space (4″-6″ will be even better!) between the rooftop and the solar panel and a 1-1.5″ space for any small-sized gadget.
• Before buying indoor solar lights, make sure they come with and extra USB-slot for traditional charging. Another important hint is the length of the cable between the lamp and its solar panel. The best one is sufficient for mounting the panel strictly to the rooftop. So you probably need to make some measurements before ordering it. Say, a 10′-12′ wire is enough for the top floor but isn’t an option for the basement.
• As for indoor or wearable solar-powered devices (such as watches, flashlights, hairdryers, fans or even cookers) make sure their batteries are able to harvest up any light on-the-go. So they will be able to charge while you’re using them or not during the day. Otherwise, you might need to turn them off and recharge, and maybe with indoor lights or even traditional electricity or Li-Ion batteries. Which goes way out of an environmental-friendly type of mind!

Advanced tip. It’s impossible to get tanned through the window. That’s why many of us think that you can’t charge a solar appliance by leaving it on a windowsill. Yet it’s the best way of doing it! The only thing to consider is to choose a battery made of amorphous silicone. It has an ability to gather more energy from the daylight.

Let there be light

Do the solar panels work in rain or on a foggy day? Yes, definitely! I’d tell you even more: solar panels do work in winter and, by the way, frosty and sunny weather is much better for a solar power system than any other weather forecast. But since I don’t think there’s an ideal climate anywhere or Earth, let me explain how to charge solar batteries without any direct sunlight around. Remember it’s always better to turn off your device to speed up the recharge and to reduce energy use in general.

Advanced tip. Always keep in mind that there’s a dependency relation between the number of scattered clouds and solar panel output. This happens because the surface of the panel gets both direct and reflected sunlight. In this case each cloud works as an additional mirror and brings more incoming solar energy. Doesn’t work same for fogs or dull white or grey sky. But if you see single clouds up above, be sure that your solar appliance will recharge even faster than under baking sun!

Method 1: any daylight will do

• Clean the surface of your panel or solar battery from any dirt, dust, water smudges or snow. Do not scrub or use any detergents that might bring damages.
• If possible, set the tilt of your solar device so it faces directly to the daylight source.
• Rotate it as the day goes by and follow the possible sun path (from the east in the morning to the west in the evening).

Method 2: indoor lamps work as well

Sometimes you need to turn on regular lighting to recharge your solar batteries. This might be either an incandescent bulb or an LED-lamp. This technique is efficient, eco-friendly and worth trying if you are already using indoor lamps for any other needs.

• Place your lighting source over a discharged device. The closer the better.
• A higher wattage lamp works faster.
• It’ll take about half a day (more than 6 hours) and depends on the technical characteristics of your device.

Method 3: add some magic

Not only Carroll’s Alice found weird things when she step through a mirror. We also might provoke a strange effect working with mirrors and their possibility to reflect sunlight. This method might work in slightly shady areas. If a shadow from an obstacle falls on your solar battery, increase the light with several mirrors.

• Better use the reflectors that are at least twice bigger than the surface of your solar device.
• Reposition the mirrors so they reflect as much light as possible during the day (a tracker is also a good option).
• Reflectors are usually used to increase solar panel efficiency and it’s already proven. That’s why it’s totally fine to add reflectors if you want to enhance the recharging effect.

When the darkness comes…

Maybe the whole idea of charging solar gadgets without the sun sounds weird to you. But recent studies show that modern solar panels do work even at night! Okay, it sounds crazy, but what I mean are those “reverse solar panels” that register any lowest wavelengths of energy and work as thermal cells. The scientists are still working on a prototype so I’ll let you know when it’s done. From this day on, we’ll have a chance to feed up all our household and appliances with renewable energy. And maybe go off-grid someday!

As you might see, low-sunlight conditions are totally acceptable for today’s solar devices. So don’t hesitate and feel free to take advantage of any lightning source to empower your solar system. Make sure you get back with feedback – I love receiving your comments. Please share if you know someone who might need this information! And see you next time!

Malcolm – Blog Author. I have several years of customer service experience in the energy sector. I am convinced that harnessing solar energy will soon be the norm around the world.