Calculating solar panel cost for new installations

When you need to know how much solar panels cost you first must determine what your solar energy requirements are

How many solar panels will I need?

Are you are ready to determine how many solar panels your installation will require to estimate your system cost for living off the grid?

This will walk you through a typical panel installation in an average house located in Seattle Washington.   These figures are rough estimates, but will help you see how to estimate how much power you will need.

Household Power Consumption

Average household power consumption varies by country, in the United states it is about 8700 kilowatt hours per year.   This works out to about 725 kwh (kilowatt hours) per month and about  23.8 kwh per day.   The average household therefore needs to produce about 23,800 watts a day to handle its energy consumption.  (Your utility bill will show the amount that your house actually uses.)

The average hours of full sunlight per day varies with location.  Typically the amount of sunlight is between 2 and 6 hours a day depending on the amount of cloud cover.  For comparison, Seattle gets about 3.7 hours/day, Los Angeles about 5.5.

Each watt your solar panel is rated for the number of watts produced.
A one watt solar panel in Seattle gets sunlight 3.75 hours a day 

(SOLAR PANEL WATTS * SUNLIGHT PER DAY *365 DAYS)/1000
= kilowatt hours that are produced annually from a one watt solar panel.

System inefficiencies

(from the battery and energy transfer)
A typical system is about 80% efficient, although this can vary considerably depending on area temperatures, inverter efficiencies, battery efficiencies and other factors.

SOLAR COST ESTIMATE - EXAMPLE

100 watt solar panel in Seattle Washington, Average House.

Solar panel watts = 100
Sunlight per day =    3.7
Days per year = 365
= (100*3.7*365) = 135050
this is how many watt hours that are produced by your panel

watt hours per year/1000 
135050 = 135 kwh (kilowatt hours per year)

Multiply kwh * efficiency
(using .8 as typical)
= 135* .8 = 108 kwh per panel.

Average house requires 8700 kilowatts per year. (Kwy)

To see how many panels this house requires divide kwy by kwh per panel
8700/108= 80.5 panels.

Prices run about $3-$5 per watt.  A 100 watt panel is around $500

Typical solar cost

a typical solar installation in seattle would therefore cost about 40k for full off the grid electricity..   Incentives for installing panels can reduce this quite a bit.   You will also need batteries, inverters and other equipment.  These components will generally double the cost of your system.

Battery systems

A battery system provides backup and allows continuous power flow by drawing on stored power.  The longer you want to store power in reserve the more batteries you will need.   If you connect to the main utility grid then batteries are optional as you can draw power from or sell surplus energy back to the grid as it is produced.

This site explores each aspect of solar panel cost from suppliers to systems and helping you find what type of system you wish to use, how many components you will need, space estimates and installation cost estimates for solar panels.

Solar panel cost.