How do you figure how many solar panels you'll need on a house?

Question

What if I wanted to run all these things with solar power, how many solar panels and what type of solar panels would it take?

computer

washer

dryer

lights (maybe like 10 lights, not all at once)

stove

refridgerator

coffee pot

Answer 1

This actually depends on the total energy output the solar panels can provide. I'm not so sure about the exact number.

Answer 2

First of all, Running a washer and Dryer would require a very large system alone. Electric stove is also probably out of question.

Most people have an unrealistic expectaion of a normal Solar system. One panel (About 3X5 ft.) only can supply about 70 Watts of power for 6-8 hours on a nice sunny day. One panel costs about $400 dollars, then you also will spend several thousands of dollars for your Inverter / controller. One panel will supply enough power for maybe 1-2 light bulbs. Each panel will only provide about 500 Watt-Hours a day on a sunny day.

An average electric house may use like 50 Kilowatt-Hours a day. That is 50,000 Watt-Hours. It would take 100 Panels. This kind of system would be very costly and impracticle for most users.

If you want to go completly solar, you must forget dryers, frost free frig, electric heat, Air conditioning, Pumps or any other large electrical loads.

I help my friends work on their systems. It is a community that has no grid power. Everyone is completely independant. Most have 12-16 panels, a large bank of batteries, and at least a 10KW Generator. These systems cost $35,000-$40,000, and still cannot provide any heat or air conditioning without running the generator.

If you want to help the environment, just buy what panels and inverter you can afford, and supplement your power needs, unless you are willing to radically change lifestyle when you go totally solar.

Another option is to get your system free from someone like the link below. Here you just pay for the power it produces and are guaranteed for something like 25 years the rate will not change.

Answer 3

Actually, you asked the wrong question.  For most people, it is "how many solar panels can I afford?"  Solar panels are expensive and the payback period (e.g., to cover the cost) is quite long time (usually a minimum of fifteen years and often much, much more).

Answer 4

Add ti all up and that should represent about 1/3 of the power u will need. We have sunlight about 1/2 of the time,then the cloudy days.

   Then there is the inefficiency's of your batteries and converters is possible 70 %. After u get it all together dont forget to mount it firm to the roof. It has a lot of surface area so if the wind blows 30 mph. could rip the whold thing off.

Answer 5

First, you have to add up all the wattages that each appliance uses. They usually have that on a plate.

Then you create a spreadsheet that lists your power uses, and the number of hours a day you will run them.

Multiply each usage by hours and divide by 1000 to get kWh per day.

(You can look at your highest monthly power bill and divide kWh by 30 to get the largest daily average usage only if you plan to run everything on this system).

Now, take the expected watts per panel, multiply by 8 hours a day and divide by 1000.

That number of kWh divides into the average maximum daily usage kWh to give you the number of panels you would need.

However, and get this very clear, you would need battery backup and controller, inverter, to make that possible, or you would need to be on grid, feeding surplus power into the grid, taking any excess or night load from the grid.

We assume you will not use PV electricity to heat water, power a furnace fan or run ventilation fans, nor have a water pump, deep freeze.

If you have gas for water heating, you should consider gas for your dryer and stove.

Those things are to avoid requiring such a large model of inverter. Also, before sizing for PV panels, consider making sure that everything is energy star, computer may want to be a laptop. lights CFL These changes can save their cost in extra PV capacity.