For buyers, if you search solar home systems in Alibaba, you will find there are many sellers who are selling a products, price of which looks very attractive.
However, if you take a deep look at their product details, then you will find out the tricky behind their product and pricing.
For example, here are the specs from other manufacturer:
The battery is 6.4V 15AH, so total is 96Wh. Let's assume the 10W solar panel is working in fully capacity, then at least 9.6 hours, but in African/South-East Asian countries, a typical day of solar charging is 4000WH/M2 ~ 5000WH/M2，so the battery has to take more than 2-3 days to fully charged( If in rainy season, it will take much longer time).
For household in off-grid areas, they must use the solar home system every night, so it means every night the battery is not fully charged, then isn't it a waste for him to pay for the so-called extra battery capacity?
So when we design a product, we firstly think about who is our audience and their typical demand,behavier and affordability.
Take our Fortune S2 as example:
Most of rural family have 3-4 rooms, and usually they use the lights from cooking time and until sleep. For farmers, suppose they sleep at 10 p.m(in fact in my childhood in rural village, we sleep at about 9 p.m, it's not like the nightcat in modern city), supposed the cooking time is 5pm, then it's abt 5 hours of lighting typically per night.
For the brightness of LED lamp, actually we benchmark it with kerosene.The lumen of a kerosene lamp is about 10lumen, and our Fortune S2 Pro have 200lumen per lamp, totally for 3 lamps is 600 lumen, which is 60X brighter than kerosene.
So according to this usage behavier, we have decided the battery capacity for Fortune S2 Pro, which is 6.4V 6AH,and in order to fully charge it per day, we take 4800wh/m2 into account, then we figure out the solar panel could be 10W. So this is our logic on product design. You have to start the product design from end-user edge.
So if you are a buyer, when you compare my product Fortune S2 Pro with other's, you might say" Your battery is small" at a glance,but that's not the all, and if you finally buy those biger battery one, you will have to increase the solar panel, then the finally product price maybe exceed your budget,you finally get waste on the long negotiation/resourcing and communication with that manufacturers.