There are so many solar panel calculators on the internet that ask you all sorts of questions about your appliances and ask you to fill in confusing forms that we've decided to try and make it a little easier for everybody.

We're going to take the "How Much Electricity are You Currently Consuming" approach so that you can get an idea of what you'd need for solar panels to generate your current level of electrical usage.

Watts Your Current Power Consumption?

Finding out your current electricity consumption levels is pretty easy if you're already hooked up to an electricity provider. Electrical companies measure and bill your usage based on Kilowatt-hours or kWh and your electrical bill will state your usage.

I took one of my average electricity bills to get an idea of how much electricity I use, but I'll be rounding numbers up so that I'll be sure to have enough electricity generation ability. My bill says that in the last 2 month billing cycle I used 210 kWh of electricity.

Daily Electrical Usage

Since there was 68 days in my billing cycle I just divide my usage by 68 (210/68=3.08) and I end up with a daily usage of 3.08 kWh. I'm going to round that up to 3.1 kWh so I'll have a little extra.

Since solar panel information is published in watts we're going to want to work in watts as well. To convert kWh into Watt-hours just multiply it by 1,000.

My example looks like this: 3.1*1,000 = 3,100 Watt-hours.

How Many Solar Panels Do I Need?

While it's important to know how much available sunlight you have to generate electricity when you're doing a formal design - it's possible to estimate to get a general idea of panel requirements to be able to produce the electricity you're currently using.

Since I'm pretty far south I'm going to go with 7 hours of sunlight to calculate my panel requirements. We get a lot more sunlight than this and my estimate is probably low but I'd rather have more generating ability than I need than not enough.

We now know our daily electrical requirements and our available hours of sunlight so calculating how many solar panels we'll need comes next.

If we have 7 hours of sunlight to generate the electricity we need we can simply divide our daily electrical consumption by the hours we have available to generate that amount of electricity.

The calculation for our example is 3,100/7 = 442.85 watts of solar panels. We can round that up to 450 or even a little more to be on the safer side of being able to generate the electricity we need.

Solar Panel Investment

If we're looking at 100 watt panels we'd have to buy 5 panels to produce the amount of electricity that we need. We know this by taking our 450 and dividing it by the watt value of the panels we plan to use (450/100 = 4.5 which is rounded up to 5 panels equaling in total 500 watts).

Just one 100 watt solar panel seems to average about $500 so total investment on the panels would be about $2,500. Keeping your eyes open for deals could save you some money because we've seen 100 watt solar panels selling for around $275 which would make the total cost just $1,375.

That doesn't seem too bad of an investment because the electrical bill in this example includes using the following electrical appliances:

• Small Energy Efficient Refrigerator (275 liters/9.7 cubic feet)
• Microwave (1050 watt)
• Coffee Maker (I love coffee)
• 2 Laptop Computers
• Cable Modem
• Router
• Various Compact Fluorescent Lights
• Intermittent Usage of Miscellaneous Chargers, Laser Printer, Woodworking Equipment, Blender, Hair Iron

Note that this example doesn't include some key items like batteries, charge controller, inverter and cable so the total investment is going to be more.

Is Generating Your Own Electricity Worth the Expense?

A lot of people might look at the expense of the system and tell you that it's just not worth it because it will take so long to pay for itself. Generating your own electricity allows you to know that your electricity is really GREEN. Generating your own electricity gives you independence from the system and any fluctuations in service quality and price.

Other Electricity Generation Options

If you live in a windy area it may make more economical sense to go with a wind and solar hybrid system - we'll show you why in an upcoming article.