The U.S. Energy Information Administration says the average US household uses about 9000 kiloWatt hours of energy a year, so let's use that as an example to provide you with an outline of cost figuring. We will assume the azimuth of roof to be 175 degrees with a 34 degree (8/12) pitch. The home's favorable orientation and slope would make this a very good candidate for a roof mount. Perfect solar south for New Hampshire is 194 degrees and for a roof mount to be most effective the compass orientation should be within thirty degrees. The performance of solar panels(aka modules) begins to fall off rapidly outside of this 60 degree "pie" and at that point a ground mount array begins to make more sense. The best compromise for pitch (slope) is around 35 degrees. A flatter pitch favors summer production while a steeper pitch favors winter production.
A simplified way to figure out how many solar panels would be needed for this example is to divide the annual kilowatt hours needed by the rating of the solar module, and then divide that result by the production factor (explained below). The 9000 kWh consumption divided by 300 watts per panel equals 30 panels, and since this is a roof mount with a decent but not perfect azimuth we would divide that figure again by the production factor of 1.3 to get a final result of 23 panels actually needed. It has been our experience that most clients would want this rounded up to 24 panels and this makes sense. The incremental cost of adding a few extra panels is low.
The production factor is a conversion mutiplier that will convert the solar panels DC watt rating into the AC kilowatt hours that you consume in your home. A perfectly oriented and sloped roof mounted array has a production factor of 1.35. By using the production factor mutiplier we can derive that a 300 watt solar module mounted on a perfectly oriented roof will produce 405 kilowatt hours annually. As illustrated in the example above however most roofs don't have a perfect orientation and/or slope and the kWh production will suffer a bit as a consequence. A roof off by 30 degrees in azimuth for example will have a production factor closer to 1.3, and if the pitch is less than ideal as well the production factor would fall off even further. Each panel in the example will produce 390 kWh.
There are three other basic types of photovoltaic solar electric installations that can be used when the roof mount is not favorable or desired. In order of cost and popularity they are; fixed frame ground mounts, manually adjusted ground mounts, and active dual axis tracking ground mounts. A fixed ground mount is usually installed with the perfect 194' azimuth and 35' pitch, thus the production factor will also be 1.35. Adjustable ground mounts usually change only the pitch 2-4 times a year, but even still the production factor will increase by roughly 7% to 1.44. The tilt adjustment on the adjustable pole mount favored by NH Solar is done with an awning crank and takes only a few moments. The motorized and fully automatic dual axis sun tracking systems are top dog and have a production factor of 1.8. The same 300 watt rated solar panel mentioned above would produce 540 kWh annually if mounted on a dual axis tracker! A side benefit to active dual axis trackers is that they ramp up to full power much earlier in the morning and fall off later in the evening.
NH Solar verifies all it computations through the government's National Renewable Energy Labaratory's PVWatts website and includes that report in our quotes. This excellent website is open for public usage and it would be advisable to use it to check any solar installers figures against it for accuracy. After you have entered your homes particulars you can easily dirive the production factor by dividing the projected kWh production by the DC wattage of your array.
The total gross cash price for the roof mounted 24 panel solar array for the home in the example would be $16,920 give or take depending on installation variables and the make of modules and/or inverter chosen.
...Now let's apply the incentives the government is currently providing to promote renewable energy and re-figure your true cost.
The largest incentive is a 30% tax credit that you will be able to claim on your Federal tax return the year after we have installed your new solar system. In this example the 30% Federal tax credit would be $5,076. This can usually be split if needed and taken against two years of income. Additionally,the State of NH PUC also grants a rebate incentive of 50 cents per DC watt, capped at $2,500. This system would be a 7,200 DC kilowatt solar array (24 panels x 300 DC watts each) and thus numerically qualify for a rebate of $3,600. However, because the State rebate is capped to a $2,500 maximum, that would be the actual rebate received. The $2,500 rebate check from the State of NH PUCdepartment generally comes back to within a month after your system is completed.
The net cost of the solar power system after applying the incentives is now just $9,344. This would be your final and actual out of pocket cost. It is important to note that your initial cost due to the installer when the system has been completed would be the $16,920 gross price. You would only be eligible to receive the NH PUC rebate and apply for the Federal tax credit only after the system has been installed and approved. The specially designed solar financing programs that New Hampshire Solar offers can make this cash flow bump very easy to accomodate. In most cases your average monthly expenditure to finance your new solar system will be very close to what you formerly were spending for your electric billings.
The cost per kilowatt hour to purchase power from one of the New Hampshire public utility companies varies, but is usually averages somewhere around 18 - 20 cents per kWh. In this example the customer had been buying an average 750 kWh per month, so the monthly utility bill at that $0.18/kWh consumption would be $135 per month ...an annual utility billing expense of $1,620 per year!
New Hampshire Solar generally recommends designing a solar system to offset as close to 100% of a customers annual electricity usage as possible, this is termed net zero. If you were to divide the net solar system cost by the annual utility bill savings you will get the amount of time it would take for the system to "pay for itself" with the utility bill savings. This is usually referred to as either the Return On Investment or Payback period. In this case the system will have justified its cost in just 5.76 years ($9,344 net/$1,620). Note that no additional funds have been spent, the funds paid out by the homeowner have simply been diverted from the expense of having to purchase power from a utility company, to the cost of buying the asset of a solar array to produce that same level of power. Best of all at the end of the ROI period you own the system outright, and from that point forward your solar electricity will be coming into your home truly for free! The expected life cycle of a photovoltaic solar system is generally thought to be forty years or more. The 40+ year life expectancy of a PV solar system less the 5.7 years of the payback period equals 34+ years of free electrical power! If you continued to purchase your power from the grid during the forty year period you will have paid a total of $64,800, and that is assuming that the rates for electricity never go up. With a PV solar system your cost for the same amount of power over forty years would be the $9,344 net cost to purchase the array. Installing a PV solar system would save this homeowner over fifty five thousand dollars during the expected 40 year lifetime of the array! It is only fair to state that there may be some required maintenance, but even in the unlikely event of an inverter failing entirely. the cost would only amount to a few thousand dollars at the most.
But wait, there's more! As you may recall from the "how PV Solar works" page, New Hampshire Solar will also install a REC meter with your system and introduce you to a company that will pay you for those Renewable Energy Credits. Every 1000 kWh that your solar system produces qualifies you for 1 REC. Since the system in this example was engineered to produce roughly 9,000 kWh annually, it will generate 9 RECs for you to sell. RECs are sold to the utilities in an auction format and as a consequence the pricing changes frequently in accordance with demand. Right now (5/1/17) RECs have a value of about 30 dollars. This example will currently produce provide an additional REC income for the system owner of $270 per year!
Lastly, a photovoltaic solar electricity system will add considerable additional asset value and marketability to your home or business. There are many ways of evaluating the worth of a solar system, but in general it is safe to say that a relatively new PV system will add value that is nearly equal to the systems gross cost. Plus if the cost of electricity purchased from the utility company rises, the value of your solar system will go up as well. A spreadsheet outlining the costs for this system can be found here
Why "rent" your electricity when you can "own" it for so much less??
Solar Electricity... good for your home, good for your business, and good for the planet!
URGENT NOTE! This summer has seen changes to both the NH PUC rebate and coming change in the net metering rate, both are going to have a significant effect on the cost of solar energy.
The PUC suspended accepting applications for the rebates effective July 13th and the future of the program is uncertain at this time. Official details can be found here
The rebate suspension will have an immediate short term impact on the cost of solar, but in the long run is no where as costly as the change in the public utilities net metering rates scheduled to take effect on Sept 1st. There is till time to contract an installation and get locked into and grandfathered at the current 1 for 1 rate until year 2040 ...but you must act now!
(TIP; to get a quick overview of the cost of solar pv just scan the boldly printed lines. Also note that there is this subtab for excels of some typical NH systems)