Nowadays, there aren’t many mountaineers in China using solar charging panels, but in fact, this demand is becoming increasingly strong. After all, there are more and more devices that use electricity, and who doesn’t want a continuous supply of electricity?

But there are also many practical issues, such as how long a solar panel can fully charge a phone, how much efficiency will decrease in case of cloudy weather, and whether the weight will increase compared to a power bank.

This article will help you analyze these issues.

The selection of solar panels – Solar panels themselves are not complicated, and when choosing, you only need to pay attention to the following parameters:

1. The wattage of a solar panel represents its peak power generation capacity. Currently, mobile phone batteries have a larger capacity, so it is recommended to choose products with a wattage of 18 or more. If the power is too low, the charging speed will be too slow, which will affect the user experience;

2. Solar energy conversion rate. At present, it is generally 14%~23%, which is used to determine whether the solar panel is excellent enough. The higher the number, the better. The conversion rate of solar panels used in general outdoor products is generally above 20%. Products with low conversion rates require a larger area to achieve the same wattage, resulting in higher weight, which is not suitable for outdoor use;

3. The types of solar panels, currently good products are generally monocrystalline silicon;

4. Do you have a built-in battery? It is recommended not to choose products with built-in batteries, as they are not commonly used and you will definitely bring a power bank with you, which adds extra weight. Additionally, the working temperature of the solar panel may be high, and it is not safe to have a built-in battery.

The above is the basic knowledge of purchasing solar panels, and of course, there are many details, such as how many sockets there are, whether the circuit is anti overload, whether it supports fast charging, etc. You can choose the details yourself, but I will go into more detail.

Next, let’s take a look at how long a solar panel can charge the device.

Watt hour (Wh) – Watt hour is the unit used to measure electricity. Both power banks and mobile phone batteries use milliampere hours (mAh) as a unit. In order to facilitate the conversion of milliampere hours to watt hours with solar panels, it is necessary to convert them into watt hours.

Conversion method: milliampere hour mAh ÷ 1000 x voltage V=watt hour Wh (milliampere hour needs to be converted to ampere A for calculation, so divide by 1000).

How many watt hours is a mobile phone or power bank approximately? The voltage of mobile phone batteries and power banks is generally 3.7 volts, which can be converted into milliampere hours: 3300 ÷ 1000 × 3.7=12.2 watt hours (for a 3300mAh phone); Similarly, a 10000 milliampere hour power bank is equivalent to approximately 37 watt hours (10000mAh ÷ 1000 x 3.7).

With a watt hour, combined with the power of the solar panel, one can determine how long the solar panel has been fully charged.

How long can it be fully charged? – The wattage of a solar panel cannot be fully utilized, and there may be significant fluctuations due to time, temperature, and sunlight angle. Generally, it can only be used for 10% to 30% of the power, unless it is during strong midday sunlight that it can reach 60% to 80%.

So, if a 21 watt solar panel has an actual power of 20% (i.e. 4.2 watts), it takes about 3-4 hours to fully charge a phone (12.1 watt hours/4.2 watts=2.9 hours, 15.5 watt hours/4.2 watts=3.7 hours).

If the estimate is more optimistic and the actual power is 30% (i.e. 6.2 watts), then filling a phone takes about 2-3 hours (12.1 watt hours/6.2 watts=1.9 hours, 15.5 watt hours/4.2 watts=2.5 hours).

Overall, a 21 watt solar panel can provide approximately 10.5 to 31.5 watt hours of electricity (actual power of 10% to 30%), assuming it is used for 5 hours a day (2 hours in the morning at the campsite, 3 hours in the afternoon at the campsite, and not used during travel). It can basically charge a mobile phone, or even a phone with a power bank.

It seems that the effect of solar panels is good, but is it cost-effective in terms of weight?

Is the weight cost-effective? – a 10000 milliampere hour (mah) power bank weighs about 240 grams (average about 8.9 grams/watt hour), while a 21 watt solar panel weighs about 630 grams (average about 30 grams/watt hour), plus using a solar panel requires at least one power bank, totaling 870 grams.

Overall, if it is a single person and the trip uses more than 4 power banks, it is more cost-effective to bring solar panels. If it is a team of 2-3 people, each person brings their own power bank and shares a solar panel, then the weight is much more cost-effective than each person bringing their own power bank.

Write at the end

As more and more electrical devices are used, the anxiety of charging during mountaineering is very obvious. To use electricity more smoothly, monocrystalline silicon solar charging panels with a conversion rate of over 20% and over 18 watts are a good choice. Especially for scenarios where a single person uses more than 40000 milliamperes of electricity or a team of 2-3 people, solar panels can not only provide electricity but also save weight.

In addition, the power bank can only carry a maximum of 20000 milliampere hours (mAh), and no matter how much, it cannot be boarded by plane or train. However, solar panels do not have this restriction, which is another reason to include solar panels.