Home Solar Power

With America’s change of government has come a larger interest in people wanting to use home solar power at home, to aid global warming and save on their increasing electricity bills.

But when you install home solar power, how much do you actually have to generate to say cut your bills by 50%? And what kind of costs will you be looking at?

Here is a simple 4-step formula to help you calculate your home’s solar panel watt requirements and costs:

1 - What Is Your Daily Power Consumption?:

To do this, get your last 12 monthly power bills and calculate your average kilowatt hour (kWh) usage per month. The reason we use 12 is because our power consumption fluctuates with the seasons. The calculation would be to add up the power used over the past 12 months and divide it by 12. But if you do not have all your power bills, then simply use last month’s one.

Then divide your monthly usage by 30 (the average number of days in a month, to get your daily power used.

- So for example: If you have a monthly power consumption of 800 kWh, then your daily amount is 800/30= 26.7 kWh per day.

- So if you want to cut your bill by 50%, then the amount of home solar power needed is 26.7/2 = 13.4 kWh per day.

2 - Calculate The Total Wattage Of Home Solar Power Needed:

To work this out you are first going to look at an insolation map to see the average usable hours of sunlight your area receives each day. A map is available on our website.

Your next step is to take the daily kilowatt hours needed and divide it by the average usable sunlight hours, then multiply that by 1.25 (this is used to take into account the inefficiencies in the home solar power system from wiring, charge controllers, batteries, and inverters).

- Continuing from our example: Our solar panel watt needs equal:

13.4 kWh required / 5.5hrs of insolation x 1.25 = 3.045 kW or 3045 Watts daily.

This means we need solar panels with the capacity to produce at least 3045 Watts of power.

3 - The Cost Of The Panels:

This step will help you work out the cost of the solar panels needed to make 3045 Watts of power. At the moment the highest average cost for solar panels in the US is $4.85 per Watt.

- Continuing with the same example, the cost of the solar panels will be 3045 x 4.85 = $14,768. This is only to reduce our power bill by 50%, and it is before the costs of charge controllers, inverters, batteries, and electricians.

4 - Subtract Tax Rebates And Subsidies:

Before you think you are going to have to fork out at least $14,768 for only 3045 Watt of solar panel power, you need to consider the effect of government subsidies and incentives.

2009’s Federal renewable energy tax credits came into effect from the beginning of the year, and coupled with the state-side incentives in places like Connecticut, California, New York and New Jersey, the cost of the home solar power system will be much less.

- Continuing on from our example: If we lived in California, our state tax incentives would be about 20 % of the investment, and the federal rebates 40% of the remaining cost. So, our solar panels would only end up costing us:

$14,768 - $14,768 x (20%) - $14,768 x (1 - 20%) x 40% = $7,089.

Since there are many factors that go into calculating your solar panel watt costs, please only use our steps as a rough estimate. Some things were impossible for us to take into account, such as special offers by solar installation companies, where they offer you discounts on the full installation (including charge controller, inverter, battery, grid-tie electrician costs, etc).

Anyway, from what you can see it would cost us around $7,089 to buy enough solar panels to halve our power bill. We, instead, either get our solar cells at cost or source them for free, and wire up our own solar panels, which obviously saved us a lot of money. The good news is, anyone can learn to find cheap solar cells and make their own solar panel watt power.

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