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I hear the phrase “grid-tie” a lot, what does that mean?

A solar pv array that is “grid-tied” is connected to the electric power distribution grid through your local electric utility’s power lines.  These are the same lines that bring power into your home or business.  Having a grid-tied array allows you to take advantage of programs that may allow you to sell power back to your utility company.

Will I need a battery backup for my solar array?

It is not necessary to have a battery backup for your solar array.  If however, you are interested in having backup power in case of a power outage, or if you want to live “off-grid”, independently of the local electric utility, then you may want to consider this option.  A solar array with battery backup is more complicated to install and can add as much as 25% to the cost of your solar array.  Battery backed systems are also less efficient due to battery charging and additional system losses not present in basic grid-tied systems.

How much space do I need to install a solar array?

The physical size of a solar array depends on the output desired.  Solar panels commonly sold today measure approximately 65” x 39”, weigh about 45 lbs, and are rated at between 200 and 230 watts each.  A solar array rated at 1 kW would require 5 panels and cover approximately 90 square feet of roof area.    Under ideal conditions (i.e. proper orientation, no shading) in Mississippi this 1 kW array would produce, on average, about 4 kWh of electricity daily (a 100 watt light-bulb will consume 4 kWh of electricity in 40 hours).  That’s about 120 kWh a month on average.  Using these numbers as a guide, a 5 kW array would, on average, produce about 600 kWh of electricity a month and would take up about 450 square feet.

I have a 2400 square foot home, how many solar panels do I need?

The more accurate question to ask is, “How many kilowatt hours (kWh) of electricity do you consume in an average month?”  Obviously a home that is designed and built to be energy efficient will consume far less electricity each month than a similar sized home that is not energy efficient.  Likewise, the choice of fuel, whether electricity or gas/propane, used for space heating, water heating, and cooking will affect the amount of electricity used monthly. 

Do this…contact your local electric utility provider and ask them for a printout of your past 12 months kWh usage.  Figure out the average kWh you consume each month and decide what your goals are.  Do you want to offset your entire utility bill with solar power, or just a portion?  Do you want to live completely free of the utility grid?  Are you interested in having some protection against rising utility rates?  Give us a call and we can help design a system that meets your needs and goals.

What is a watt and how many watts will a solar array produce?

A 100 watt (W) light-bulb consumes 1 kilowatt hour (kWh) of electricity if left on for 10 hours (i.e. 100 W x 10 hrs = 1,000 Wh or 1 kWh). 


Solar arrays are often referred to as some multiple of kilowatts…a 2.4 kW array is a 2,400 watt array, a 3.2 kW array is a 3,200 watt array, etc.  Commonly sold solar panels today are rated at between 200 and 230 watts (W) each.  A solar array rated at 1 kW would require five 200 watt panels.  Under ideal conditions in Mississippi (i.e. proper orientation, no shading) this 1 kW array would produce, on average, about 4 kWh of electricity daily or about 120 kWh a month on average.  A 5 kW array would produce, on average, about 600 kWh of electricity in a month.

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