FAQ

How does SONNENGLAS® function?
SONNENGLAS® is equipped with LEDs which are charged via the solar cells in the lid. As you expose it to the sun, SONNENGLAS® starts fueling with energy. This energy will be used at a later point to give you many hours of soft but bright light. By flipping the magnetic handle, the electronics inside of the lid will be activated and your SONNENGLAS® lights up. In case of cloudy day or lack of sun you can conveniently charge your SONNENGLAS® with the Micro-USB port.

How long does SONNENGLAS® light up for you?
Once fully charged, SONNENGLAS® can provide up to 24 hours of light. It truly depends on the exposure to the sun whether your SONNENGLAS® can be fully charged within one day. As a golden rule we can say: on a cloudless summer day, one hour of direct sun exposure equals one hour of light. If you adjust the angle of your solar cell to the position of the sun, you will optimize the charging process.

How long does my SONNENGLAS® hold a charge?
The battery of your SONNENGLAS® will hold its charge over months. After one month of shelf life the battery suffers less than 3 percent of its charge.

How long is the lifespan of the battery?
The battery is designed to last for at least 800 load cycles. In normal use, its life expectancy is around 5 years. Of course, you do have 2 years of warranty on your SONNENGLAS®. After your warranty has expired, feel free to take advantage of our battery exchange program.

How bright is the light of SONNENGLAS®?
The SONNENGLAS® Classic and Mini have 15 - 30, and 12 - 25 lumens respectively. You may perceive SONNENGLAS® to be brighter than this though. The light shines onto the bottom made of glass and is reflected from there which is what might lead to that impression.

Which temperature does the light of SONNENGLAS® have?
The LEDs in SONNENGLAS® have a color temperature of 3500 Kelvin. We think that it perfectly matches with the glass. The underground, as well as the decoration filled into SONNENGLAS® might slightly influence the way you perceive the color temperature.

How long does it take until my SONNENGLAS® is fully charged?
That widely depends on the strength of the sun exposure, and thus from the season as well. In direct sunlight, you will likely need 6-9 hours of charging during summer time. In spring and in fall give it around 10-12 hours to charge. In winter it can take several days until SONNENGLAS® has been fully charged. Of course, it all depends on where you are geographically located. For an ideal absorption of energy, incline your SONNENGLAS® in order that the sun rays hit the surface at right angle. To charge your SONNENGLAS® the fastest way, simply use your Micro-USB cable. It only takes 4 - 5 hours to fully charge it this way.
Can I overcharge the battery of my SONNENGLAS®?
No. You can neither overcharge your SONNENGLAS® by exposing it to sunlight nor by having it connected to the Micro-USB cable during the charging process.

Is interior light sufficient to charge SONNENGLAS®?
No, SONNENGLAS® requires natural sunlight for charging. A cloudy sky does not prevent your SONNENGLAS® from getting charged but makes this a longer process. Interior light on its own is never sufficient, unfortunately.

My SONNENGLAS® switches itself off after a few seconds only. What is this about?
A drop of the battery’s capacity under 15 % will result in the LEDs automatically switching themselves off after a few seconds. This automatic process prevents the battery from getting fully discharged and thus prolongs its lifespan. Your SONNENGLAS® is now in need of an intense portion of energy! Either via natural sunlight or the Micro-USB port which you find at the bottom of the solar module. All you need in order to benefit from this feature, is a regular Micro-USB cable.

My SONNENGLAS® does not shine. What can I do?
First you should make sure that your SONNENGLAS® has been sufficiently charged – either via natural sunlight or via the Micro-USB port. Please also verify that the magnet of the clip is correctly positioned in order to close the circuit. Should your SONNENGLAS® still not want to shine, please contact our Customer Service team. We are looking forward to helping you!

My SONNENGLAS® does not shine for long enough. What can I do?
Your SONNENGLAS® might not have received enough sunlight or energy via the Micro-USB cable. Assume it has, please make sure that the flat round metal button on the metal handle is positioned correctly, i.e. on the grey dot on top of the solar module. Only when the circuit is closed, your SONNENGLAS® can light up. In case it still does not want to shine, we recommend to provide your SONNENGLAS® with a very intense charge in order to “kick-start” the battery. This simple measure referred to as “calibration” has already brought many SONNENGLAS® lamps back to life… and here is how you proceed: charge your SONNENGLAS® intensively – for at least 5-6 hours – over the Micro-USB cable. It is as simple as that!

Do not switch or leave your SONNENGLAS® on while you are charging it. Put your SONNENGLAS® - or just the unscrewed lid - at an angle that makes the sun directly shining onto it. Like this you allow a maximum of energy absorption.

Even after the calibration is your SONNENGLAS® still too dark or not shining for long enough? We will be more than happy to assist you with that! Please contact our Customer Service team under info-japan@sonnenglas.net and provide your serial number from the white sticker on the bottom of the solar module. We will handle your issue A.S.A.P.

How do I get the magnetic switch into the correct position?
In order for SONNENGLAS® to operate, the magnetic switch and the point on the solar module must be in the same position. To accomplish this, either turn the metal frame until both points touch, or place the module with the point at the desired position, hold it secure, and tighten the screw ring.


The solar module of SONNENGLAS® consists of 3 different parts. Is that intentional?
Yes, the solar module in older versions of SONNENGLAS® consists of three parts: the solar module itself, the rust proof threaded ring and the sealing ring. All of these three parts need to be loose in order to function properly. The threaded ring, e.g., is loose in order that it can be turned individually and independently from the solar module. As for the sealing ring: It is not fixed either since it needs to comply with the turning movement during the screwing process.

Where do I find the serial number?
The serial number is located on the side of the solar module, on the white sticker, right next to the barcode.

How do I ideally store my SONNENGLAS®?
You don’t intend to use your SONNENGLAS® for a longer period of time? Try to keep it at a bright spot though. If you prefer to store it in a dark environment or put it back in the box, please fully charge it before doing so. This helps to protect the battery of SONNENGLAS® and increases its lifespan.

Which decoration can be placed in my SONNENGLAS® and what should I avoid?
You can show all your creativity when decorating your SONNENGLAS®. Sand, stones, blossoms, shells – there are endless options to decorate your SONNENGLAS®. Just make sure that you only use dry materials for this purpose. SONNENGLAS® does not like liquids and food items. They may seriously harm the electronics inside and make SONNENGLAS® fail to work.

How do I charge via the Micro-USB port?
If the sun just does not want to show up, use the Micro-USB port as an alternative to charge your SONNENGLAS®. All you need is a regular Micro-USB cable. Plug it into the Micro-USB port at the bottom of the solar module and allow 4-5 hours for charging.

Questions about South Africa / Fair Trade Background
SONNENGLAS® is a handmade item from Johannesburg in South Africa. The production originally started with 3 employees. Today, 65 women and men are working in the manufacturing process of our SONNENGLAS® lamps. Most employees are coming from Soweto and Alexandra (townships in Johannesburg). They are paid above the general pay scale and receive insurance and pension claims. SONNENGLAS® should not be mistaken with a charitable project. Our project rather favors the approach “trade instead of aid”. We are very proud that a South African company has reached international success thanks to its good product.

Is my SONNENGLAS® protected against rain?
SONNENGLAS® must be screwed tightly shut so that no water can enter the glass container. SONNENGLAS® is waterproof according to protection class IP67 (rain and short-term immersion). This applies to the solar module of a product that is correctly screwed shut. However, if SONNENGLAS® becomes damp inside for a short time, this will do no harm. Simply allow it to completely dry out again.

My SONNENGLAS® only flashes briefly or can no longer be switched on. What can I do?
If the battery of SONNENGLAS® lantern is empty, it flashes 3 times during a switch-on attempt and then switches itself off. What your SONNENGLAS® now needs is a good shot of energy, either from the sun or through the micro-USB port.

How can I cancel my order?
Please contact us at info-japan@sonnenglas.net. We will be more than happy to help.

Does my SONNENGLAS® come with a warranty and how can I extend it?
Your SONNENGLAS® has a 1-year-warranty. You can extend this warranty to 2 years free of charge. All you have to do is to register the serial number of your Sonnenglas from the warranty registration form of this website within 2 months after your purchase and fill in a few details.

I want to resell SONNENGLAS®. What do I need to do in order to become a reseller?
If you want to become part of our SONNENGLAS® family please contact us by email under b2b-japan@sonnenglas.net. We are looking forward to reading more about your plans and thoughts about SONNENGLAS®.