With America's change of government has come a larger interest in people wanting to use solar power at home, to aid global warming and save on their increasing electricity bills.
But when you install 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 - Calculate Daily Power Used:
Your first step is to work out the average daily kilowatt hours (kWh) used. This can be done by looking back at your last twelve months power bills, and see how much power used per month, and get the monthly average. This will give you a better estimate of your average power needs by eliminating the effect of the seasons. It is calculated by adding up all 12 bills and dividing the total power used by 12. If you do not have the the past year's bills, then look at your most recent one.
Then divide your monthly usage by 30 (the average number of days in a month, to get your daily power used.
- Let's use an example: If our monthly energy usage is 800kWh, then the average daily power used is: 800/30 = 26.7 kWh a day.
- So to reduce your electricity bill to half, 26.7/2 = 13.4 kWh of solar power per day is needed.
2 - Calculate The Total Wattage Of Solar Power Needed:
Before you can work this out, you need to find out how many usable hours of sunlight your region gets per day. A simple way to find that out is to have a look at an insolation map - there is one available on our website, where the original article was posted.
Now take the average daily kWh calculation and divide that by the number of daily usable sunlight hours, then multiply that by 1.25 (to take into account the wasted energy from wiring, charge controllers. batteries, and inverters).
- From our same example, if we lived in California where it gets on average 5.5 hours of usable sunlight per day, the solar panel watt requirements are:
13.4 kWh / 5.5hrs x 1.25 = 3.045 kW or 3045 Watts per day.
This indicates that our home solar power system must have the minimum capacity to produce 3045 Watts of power.
3 - How Much Will This Power Cost You?:
Next you need to work out how much it will cost to buy solar panels that produce at least 3045 Watts. Currently the highest average cost for solar panels in North America is $4.85 a Watt.
- Following on from our example, the solar panels will cost 3045 x 4.85 = $14,768 to only halve our monthly power costs. This excludes the cost of wiring, charge controllers, batteries, inverters, and installation fees.
4 - Offset Tax Credits And Rebates:
Before thinking that your solar power investment is going to be $14,768 to only halve your power bill, you need to subtract any tax rebates and subsidies on offer.
With the new renewable energy tax credits going into effect from January 1, 2009, and state-side rebates from states such as New York, Connecticut, New Jersey or California, our solar installation costs will be much lower than expected.
- Let's use our example: If we were from California we would receive tax rebates of about 20% of the cost, and a federal tax credit of 40% on the remainder. So after rebates and credits, our solar panels would cost 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).
But, from our example it would cost a Californian about $7089 to invest in solar panels that can reduce his electricity bill by only 50%. We, on the other hand, know how to source cheaper and even free solar cells, and build our own solar panels, which makes the cost MUCH lower. If you are a DIY fanatic then it would save you a lot of money if your bought a solar power guide that show you how build your own solar panels.
But when you install 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 - Calculate Daily Power Used:
Your first step is to work out the average daily kilowatt hours (kWh) used. This can be done by looking back at your last twelve months power bills, and see how much power used per month, and get the monthly average. This will give you a better estimate of your average power needs by eliminating the effect of the seasons. It is calculated by adding up all 12 bills and dividing the total power used by 12. If you do not have the the past year's bills, then look at your most recent one.
Then divide your monthly usage by 30 (the average number of days in a month, to get your daily power used.
- Let's use an example: If our monthly energy usage is 800kWh, then the average daily power used is: 800/30 = 26.7 kWh a day.
- So to reduce your electricity bill to half, 26.7/2 = 13.4 kWh of solar power per day is needed.
2 - Calculate The Total Wattage Of Solar Power Needed:
Before you can work this out, you need to find out how many usable hours of sunlight your region gets per day. A simple way to find that out is to have a look at an insolation map - there is one available on our website, where the original article was posted.
Now take the average daily kWh calculation and divide that by the number of daily usable sunlight hours, then multiply that by 1.25 (to take into account the wasted energy from wiring, charge controllers. batteries, and inverters).
- From our same example, if we lived in California where it gets on average 5.5 hours of usable sunlight per day, the solar panel watt requirements are:
13.4 kWh / 5.5hrs x 1.25 = 3.045 kW or 3045 Watts per day.
This indicates that our home solar power system must have the minimum capacity to produce 3045 Watts of power.
3 - How Much Will This Power Cost You?:
Next you need to work out how much it will cost to buy solar panels that produce at least 3045 Watts. Currently the highest average cost for solar panels in North America is $4.85 a Watt.
- Following on from our example, the solar panels will cost 3045 x 4.85 = $14,768 to only halve our monthly power costs. This excludes the cost of wiring, charge controllers, batteries, inverters, and installation fees.
4 - Offset Tax Credits And Rebates:
Before thinking that your solar power investment is going to be $14,768 to only halve your power bill, you need to subtract any tax rebates and subsidies on offer.
With the new renewable energy tax credits going into effect from January 1, 2009, and state-side rebates from states such as New York, Connecticut, New Jersey or California, our solar installation costs will be much lower than expected.
- Let's use our example: If we were from California we would receive tax rebates of about 20% of the cost, and a federal tax credit of 40% on the remainder. So after rebates and credits, our solar panels would cost 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).
But, from our example it would cost a Californian about $7089 to invest in solar panels that can reduce his electricity bill by only 50%. We, on the other hand, know how to source cheaper and even free solar cells, and build our own solar panels, which makes the cost MUCH lower. If you are a DIY fanatic then it would save you a lot of money if your bought a solar power guide that show you how build your own solar panels.
About the Author:
Good news is that you can now try the Earth4Energy Ebook for FREE, before deciding to build your own solar/wind power system, and slashing your electricity bill by as much as 80%. Another guide to consider getting is Efficient Planet. Follow the link to read the full review.
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