Solar Energy Frequency Asked Questions
How many solar panels should I install?
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A typical house will need about 10kW of solar panels (25 panels at 400W each) if you want to produce all of your own energy.
Solar systems are usually sized so that they produce enough energy to equal your AVERAGE electrical bill. Some months you may produce more energy than you use, and some months you may produce less. You can rollover excess energy production from one month to the next.
How much will a solar system cost?
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The installed cost of a typical 10kW solar system on a shingle roof is around $25,000. ($17,500 after the Federal Tax Credit of 30%.)
Our solar system costs vary between $2.25 and $3.00 per watt depending on system complexity and roof type. This means that an 10kW system will normally cost between $22,500 and $30,000. This is before the federal tax credit of 30%.
Some things that may increase your cost per watt:
Difficult roof access
Tile roofs
Smaller system size
How much money will this save me on my electrical bill?
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A 10.0kW system will save you around $275/month on your electric bill.
Here in St. Petersburg, a 10kW system should produce 50kWh per day (or 1500kwh per month.) Duke Energy currently charges between 18 and 19 cents per kWh, so this your monthly savings would be around $275/month.
Will my electric bill go to zero if I install solar?
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No, Duke Energy has recently added a minimum charge of $30.00 per month for all customers.
What is the payback period for a solar system?
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It will usually take around 8 years to save enough money on your electric bill to equal the full sytem cost. However, with financing, many people can start saving money from day one.
Many customers will finance their solar system so tat the monthly payment on the solar loan will be less than the previous power power bill.
Installing solar also insulates you from any increases in the cost of energy from the electric company.
Finally, after the loan is paid off, you own the solar system outright.
How long will a solar system last?
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Solar panels are usually warranted to produce at least 80% of their original power rating for a period of 25 years or more. The panel life is probably much longer than that. The power electronics (we typically use micro-inverters from Ehphase) are warranted for 25 years.
Will my solar panels run my home when the power is out?
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Finally, the answer is YES! Enphase has released their IQ8 line of microinverters that produce power even when the electrical grid is down.
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Should I install batteries with my system so that I can go off-grid?
No. We do not feel that batteries are financially beneficial yet.
Here are some reasons why we think batteries are not a good investment yet:
1. The state of Florida has net-metering laws that require the power company to let you use the electrical grid as a free battery.
2. Batteries are still quite expensive. (For example: Installing two Tesla PowerWall battery costs about $18,000 after installation, and they will run your home for about 12 hours.)
3. Batteries degrade over time, and will need to be replaced periodically.
4. Battery technology is still improving rapidly, and the next generation of batteries looks to be less expensive and longer lasting.