Sizing a solar generator for a laptop setup is mostly about two numbers: how much power your devices use at one time, and how long you want them to run. The good news is that a laptop is usually a fairly light load compared with things like heaters or kettles, so you often do not need a huge unit.
Start with the laptop charger rating, which in your case is 65W. That does not mean the laptop always pulls 65W, but it is a safe number to use for estimating. If you also plan to run a monitor, add its wattage too. Many monitors use somewhere around 20W to 40W, while a Wi-Fi router is often around 8W to 15W. If you wanted to run a 65W laptop, a 30W monitor, and a 10W router at the same time, you would be around 105W total. It is smart to add a little margin, so think more like 120W to 130W continuous output.
Next is battery capacity, which is usually listed in watt-hours, or Wh. This tells you how long the generator can supply power. A simple way to estimate runtime is battery Wh divided by your total load in watts, then reduce that a bit because no system is 100% efficient. For example, a 300Wh unit powering a 100W load might give roughly 2.5 to 3 hours in real use. A 600Wh unit could give around 5 to 6 hours. If you only need to charge the laptop and run the router, a smaller unit may be enough. If you want several hours with a monitor included, 300Wh to 500Wh is a more comfortable range.
The inverter matters too, but for a laptop setup it usually does not need to be huge. Most laptop chargers are well under 150W, so even a 300W or 500W inverter is often plenty. Surge rating is less important for a laptop than for appliances with motors, but you still want the inverter to handle your peak load without tripping. If you are using USB-C charging directly from the power station, that can be even more efficient than using the AC outlet and laptop brick.
One thing people often overlook is the charging side. If you want the solar generator to be useful during longer outages, make sure the solar input is realistic for your panels and your local sunlight. A 200W panel will not always produce 200W, especially in weak sun or bad angles. For a laptop-focused backup, a battery in the 300Wh to 700Wh range with a good quality inverter and at least one fast charging option is a practical sweet spot.
If you want the safest approach, list every device you plan to run, add their wattages, and then choose a unit with about 25% more output capacity than your highest expected load. That keeps the system from running at its limit and gives you room for a second device later.
