we are planing to move out of the grid. we need to operate constantly 2 laptops online - does any one can tell us how much solar panels we shall need to make sure of that?
My guess is that you might find everything concerning solar power at www.okorder .
Are you going to have anything else on electric? Water heater, Stove, Refrigerator, Dishwasher, Washing machine, lights, fans, or a barn with lights and possible water heaters for winter? If so, you may need a lot more panels than that. We use 6.8 kW of panels in a place not known for sunny days, and do all right, but sometimes have to be careful if it is cloudy for many days in a row. You may be able to get by with about half of that if you live in a sunny, southern clime. Good luck - there are lots of non electric options for other (non-laptop) appliances, so you could cut back on other stuff as well.
A laptop is about 70 to 00 W, and you have two. You also may need to power a router, and modem. So, about 50W to 250W contineous should cover it. To save power when not in use, you can let the display go blank. This will reduce your solar pannel, and battery size, and cost. You will need batteries, and blocking rectifier to store the energy for use at night, and a 300W to 400W inverter. Checkout the link below for purchasing solar equipment. You can only hope to get about 8 to 9 hours of full output from your solar pannels, and 80% efficiency. The laptops will be on and using about 200W for the 8 hours during the charging period. So your pannels, need to produce that plus 2 times more than this amount, so you can charge the batteries for the evening, at the same time. So for 24 hour operation, you will need 200W x8hrs for the laptops, plus (6 hours*70W)/8=340W avg. Total of ~540W for 8 hours. Assuming you use power saving modes when not in use, you can probably get away with 3x60W -- 520W to 600W pannel. ( Thuja is right, a few cloudy days may knock you offline) Batteries. A common low cost ( $40) automotive battery can hold about 40 Amp/hours at 2V. Under load, you may get 35 Amp hours at 0V, which is about 350Watts for one hour. You need about 80W avg for 6 hours, or ~ 2900Watt Hours. Which means you would need 9 automotive batteries. Deep storage batteries cost more, but are more durable. 6*00W pannels, $460*6 ~ $2800 Inverter $70 Batteries $400 Battery cables, rectifier, lugs, connectors $50 There are probably some other hidden costs. I was rooting for you, but it appears to be pricey. Another thing you can do, is to use the new energy efficient RF florescent bulbs for lighting. The color and brightness are excellent, and a 60W bulb only uses about 3W, and they last a lot longer as well.
