There are several different companies offering methods for securing panels to your roof. While they do differ somewhat, they all have the important task of securely attaching the panels while providing a weather-tight seal for each roof penetration. The image below shows one companies approach (Quick Mount PV). They use an engineered combination of roof flashing, lag bolt and sealing approach that accomplishes a long term, highly reliable weather-tight connection to your roof. The installer simply locates your joists, lags into them and positions the flashing under your existing shingles. They then attach the aluminum rails that the solar panels are then secured to. It’s a fairly straight forward and well thought through approach. Make sure you have a south facing roof and don’t have any obstructions (ie. trees) while the sun is up. See ya on the sunny side…
Basic electrical theory says that a Watt = Volts (V) x Amps (I). Watts are also sometimes referred to as “power”. Knowing this allows you to correlate the power requirements for different things. The image below shows how many 200 watt solar panels you’d need to run a corresponding number of 100 watt incandescent light bulbs. In very rough terms, if these 5 solar panels collected 5 hours of energy from the sun in a given day (5KWh) you’d logically be able to run 10 100W (.83A @ 120V) incandescent light bulbs for 5 hours as well. Using more efficient equivalent 30W compact fluorescent light (CFL) bulbs could allow you to run 3 times as many light bulbs. The following NREL website provides examples of the power requirements for different household items. Using some of that data, you could extrapolate that these same 5 solar panels capturing 5 hours of sun a day (5KWh) might run your oven on bake for approximately 4 hrs a day or run an energy efficient refrigerator for 55 hours. You wouldn’t need to capture the energy because you’re feeding your power into the power companies’ grid and they give you the credit towards your power bill.
Some companies are mounting AC and DC electronics on the backs of the solar modules either within the junction boxes or other separate boxes (ie. micro-inverters, DC converters, etc). Some of the companies are Tigo, Esmolo, Enphase, Shoals, SolarEdge, Azuray, Westinghouse, Huber Suhner and many others. One of the primary reasons claimed for doing this is to improve the overall energy harvest of the module and system. Other possible reasons are listed below.
– Remote monitoring
– Remote shutdown and control
– Start up and shutdown ramp rate control
– Voltage control and boost (inverter matching)
– Arc fault interruption (fire protection)
– Maximum Power Point Tracking (energy harvest)
– Module theft protection
– Installation safety
– Remote troubleshooting
Opponents (ie. central inverters and combiners) to this module level “granularity” claim that these on-board module solutions add unnecessary cost, complexity and lesser reliability to system designs since, as they claim, the central solutions offer much of the same features at lesser complexity and cost. The debate continues…
Many people consider the AC inverter the heart of a solar PV system. It’s typically the electronics that converts the DC output of the solar module into the AC voltage needed to connect to the utilities’ power grid. There are a variety of companies making these AC inverters including SMA, Satcon, Delta, ABB, Fronius, Kaco, Enphase and many others. Enphase has an interesting solution in that they put an individual “micro” inverter physically on or at the solar modules thereby making the output, as they claim, a less dangerous and more easily managed 220VAC low amperage output that is already grid compatible. Some of the important things that AC inverters do are as follows:
– Provide good “end to end” power conversion in terms of Grid Integration and Interoperability (ie. Maximum Power Point Tracking and Low Voltage Ride Through)
– Anti-islanding (the inverter disconnects from the grid when grid power shuts down for any reason)
– SCADA (supervisory control and data acquisition) – Remote monitoring, control and reporting.
– There are also efforts to integrate DC arc monitoring and prevention into them as well.
Here’s a published list of our ideas. https://sunlution.wordpress.com/ideas/ We are seeking engineering, funding and commercialization partners. Please feel free to contact us with any interest (firstname.lastname@example.org).
Just like all the energy sources the US has adopted over the past 100 years have received subsidies (and many are still receiving), so has solar PV. While some of these solar subsidies and credits may have unique and unfamiliar names, they are all just merely means to help you offset the costs of your solar installation. Here are just some of the approaches currrently being pursued…
Federal and state rebates
With the adoption of the Energy Policy Act of 2005 and the subsequent Energy Improvement and Extension Act of 2008, the US federal government provides a 30% tax rebate towards a residential solar power system with currenly no limit on how much can be claimed. There are also state level rebates as well. These federal and state level rebates are listed at the following website… www.dsireusa.org/
Many energy companies are implementing programs that allow residents to “sell” the extra solar PV electricity they produce back to their energy companies. If the customer’s system generates more than they consume the specially built meter simply spins backwards.
Renewable Energy Credits (REC)
RECs usually take form as a check written directly to the homeowner for a percentage of the system. Private companies (PPAs, module OEMs, etc) as well as utilities and state governments will offer these RECs at some predefined amount. For example, private companies will sometimes offer you a defined “per watt” deduction to a purchase if you buy their modules or tie into their system and then pursue the REC with the local utility.
Feed-in Tariffs (FiT)
FiT’s are a policy mechanism designed to accelerate investment in renewable energy technologies. It achieves this by offering long-term contracts to renewableenergy producers (like yourself), typically based on the cost of generation…which means you would get paid for the energy you produce.
Want to learn more about Idaho’s solar incentives (or lack of in some respects), here is a very good discussion… http://solarpowerrocks.com/idaho/