Our Home Solar Project
Step-By-Step
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Our Home Solar Project Step-By-Step
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How do you reduce or eliminate your dependence on fossil fuels?
That was our motivating question, so we decided to take the plunge and try to find some answers. We are a typical household in Fairfax, California and started this project knowing little about alternative energy sources. This Web site is simply a record of our progress - perhaps we'll stumble onto some information that will be useful to others. If you are interested in reducing your dependence on fossil fuels, please read on!
Here are the steps we took so far:
1. Find the easy and obvious ways to reduce your energy use. Start by turning off unused lights and appliances.
2. Replace all incandescent light bulbs with compact fluorescent or LED. They can put out the same amount of light while using a fraction of the wattage.
3. Get out your energy utility company's monthly statements for a full year. Our utility (PG&E) shows our energy usage on each monthly bill. Determine the amount of electricity usage for each month in kilowatt/hours (kWh) then calculate what your average usage is per month for the entire year. We determined that we used an average of about 500 kWh of electricity each month over the duration of the year.
4. Use one of the online calculators to determine how photovoltaic (PV) modules can generate the electricity you use. We used the Solar Estimator located at this Web site.
http://www.findsolar.com/index.php?page=rightforme
Select your state and county, information for Electric (PV), and what your average monthly usage is. I entered 500 kWh as determined at step 3. The site calculates an estimated solar system size and cost based on your location and energy needs. Of course these are very rough estimates. The actual system size and cost depends on many factors. The site even provides a list of solar contractors and installers for your local area.
5. We decided to work with the following people on our solar project after receiving an estimate and the information we needed to move forward. We knew how we wanted to proceed, but a licensed electrician is required to do the work in order to link into the grid and to qualify for rebates. In this case the electrician happened to live here in town. Overall, we have been happy with the results.
http://www.ccenergy.com/index.html
Of course, there are a number of other good solar contractors and installers to choose from.
Rebates: There may be rebates and tax incentives available depending on where you live. A substantial rebate was available to us at the time from the State of California. We also received a federal tax incentive.
6. We were encouraged to install a solar system that produced somewhat less than our actual usage. That way we would save money on the cost of the system, and we would have an incentive to further reduce our energy usage. The benefit would be the ability to break even on the cost of the system in less time. Instead we decided to install a larger system that would produce the same amount of electricity we currently use. The reason was to have surplus energy after reducing our current usage to power additional things in the future. The result turned out to be a 3.3 kilowatt (kW) system. That means the system is capable of generating a peak output of 3300 watts at full sun at mid summer. A few ideas for using the surplus energy:
- Convert our natural gas water heater to a water heater that uses solar generated electricity.
- Convert our forced air gas heater to solar generated electricity, or use electric space heaters instead.
- Consider charging an electric or plug-in hybrid vehicle from solar generated electricity!
At this point it's too soon to know how much of a surplus we'll have. Check back in a year!
A note about watts and watt/hours: the meaning can be confusing. Watts refer to the amount of electrical current being used at any given moment. For example, a 100 watt light bulb is burning 100 watts of electricity at the moment you turn on the switch. A 3.3 kilowatt (kW) solar system is designed to produce 3300 watts at any given moment under the maximum amount of sun. Watt/hours is a measurement of accumulated electricity, or an amount of electricity over time. For example, when you run a 100 watt light bulb for 24 hours, it takes 2400 watt/hours (or 2.4 kWh) of electricity to do that. We figured that we use an average of about 500 kWh (kilowatt/hours) of electricity per month based on our utility bill. Based on that, we determined we would need to design a 3.3 kW (kilowatt) solar system to cover that amount of usage.
7. Generally you have two choices when it comes to storing the electricity your solar system produces. You can keep batteries for this purpose if you want to be completely separate from your energy utility's power grid, or you can feed the power as you produce it into the the power grid, and take the electricity back out of the grid as it's needed. There are pros and cons for each approach so you'll need to do some further research if you don't know what those are. We decided to utilize our energy utility's power grid because that approach is much easier.
8. The next step is installing the solar system! The following pictures will help describe the process.
Our roof was in bad condition so we decided to replace the roof at the same time as the solar panel installation to reduce the chance of leaks. Once the old roof was removed the standoffs for mounting the PV modules could be installed directly onto the roof decking which was covered with a new layer of tar paper.
The aluminum standoff is mounted directly to the roof decking, the screws anchoring into the rafters.
Once all the standoffs are installed, flashing is placed over the standoff and sealed, then the roofing work is completed.
Aluminum brackets are installed to the standoffs in order to mount the rails.
The aluminum cross rails are attached to the standoffs. The PV modules will be attached to the rails.
While the roof was being replaced we had the opportunity to install three Solatube skylights. These were easy to install and they help to provide sunlight to three of the darkest areas in the house. This means we are less likely to turn on lights in the house during the day. The Solatube system is basically a metal tube with a highly reflective surface that "pipes" sunlight into the house.
A palette of twenty-two PV modules arrive!
Each PV module is rated to produce 175 watts at peak output. These modules were manufactured by SolarWorld.
The PV modules are mounted to the rails and the wiring is serially connected.
The electrical wiring from the PV modules connects into this switch box which is also mounted on the roof. The fire department requires this emergency shutoff to be located on the roof near the PV modules. The purpose is to protect firefighters from the electricity being generated by the PV modules in the event of a house fire.
The electrical wiring runs from the roof and through the wall into the garage.
Once in the garage, the wiring will connect into a DC to AC inverter which will be installed here.
The inverter takes power from the PV modules which produce DC power and converts it to AC power for the utility grid. This is a Sunny Boy 4000US inverter which is designed to handle up to a maximum of 4000 watts. The inverter shuts off at night and automatically turns on in the morning once it detects enough DC voltage from the PV modules to start up. The inverter tracks the current amount of power being generated (in watts), the total amount produced so far for the day (in kilowatt/hours), and the total carbon dioxide saved. SMA, the manufacturer of this inverter, provides an accessory transmitter (for an extra cost) that will plug into the inverter and transmit the data to a computer for tracking and graphing the output.
Electricity from the inverter passes through this meter before the wiring goes back through the wall to the power utility's meter and on to the grid. This meter will allow to us to keep track of the total electricity produced (in kilowatt/hours) before it ties back into the power utility's system. We can compare this meter reading to what appears on our monthly utility statement.
9. What's the next step? Solar electricity is now being generated and fed into the power grid. We will see how the amount generated compares to the amount we use after the first year.
Stay tuned!
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