@Aviator
Hujasaidia huyu jamaa umemkosoa tuu. He needed to be taken through the process of sizing the system.
The OP's question
Can someone tell me how much power I need to charge 5 laptops, a router and 10 x 7 watt lights? Assume each laptop requires 400 watts per day.
@bigDog
You need to determine how much power you actually need per day. This is basically a summation of the product of the power rating (WATTS) of each appliance and the daily number of hours of use.
For instance in your case assuming that each of the laptop, router and lights will be used for 6 hours a day/night.
Your power need per day will be
5 laptops x 60 W (assumed) X 6 hours = 1800 Wh
10 Lights x 7 W X 6 hours = 420 Wh
1 Router x 20 W (assumed) X 6 hours = 120 Wh
Your total daily power need is 2340Wh = 2.34KWh
I think this answers your question
I will go ahead and help you understand how to size a Solar PV system to power this needs.
How many Solar PV modules? what capacity?
If you have 6 hours of sunshine daily in average - the power output rating of your solar PV modules will be 2340/6 = 390 W Peak. This can be met by 4 PV modules of 100 Wp each or 5 PV modules of 80Wp each giving you 400 W peak.
How many batteries? what capacity for each?
The battery capacity is measured in Ah. If your system will be a 12 VDC system,
your needed battery capacity in Ah will be 2.34/12 = 195Ah.
However its not advisable to drain a battery 100%. it has adverse effect. We therefore size the system with a 70% percent level of discharge.
Hence our needed capacity will be 195/0.7 = 278 Ah. Its also understood that the sun does not shine 365days a year in july typically the sun will disappear for a few days. Hence our battery capacity should cover a few days without the sun typically 3 days. we call it days of autonomy
Hence our needed battery capacity now becomes 278x3 = 835 Ah.
Assuming that you want to use 100 Ah deep cycle battery, you will need 9 pieces which will give you 900 Ah capacity in total. I hope by now you understand that the system sizing is dependent on a number of factors. The most important being
1. Your location which determines your solar regime which influence how much power your PV array will generate per day.
2. Your needed level of autonomy which will determine your required levels of battery capacity to take you through the worst months.
3. Your system voltage - will the system remain DC or you will invert to AC? If AC you will have to factor loses during the inversion process.