2015 Policy May Make It Easy to Purchase Solar in Virginia

- What Is the Electrical Demand of My Current Home?
- How Much Electricity Does a New Home Need?

- The Right Size of a Home Solar System
- On-Grid Solar Systems
- On-Grid Solar System with Battery Backup

- Are Solar Panels Expensive?
- Are Solar Panels a Good Investment?

Before you can estimate the cost of the solar panels , you’ll first need to size the system, depending on how much electricity the house demands, as well as the additional you would like the solar system to produce. Once you or one of our professional partners know the needed power, you can then calculate the cost of purchase and installation. Will the solar panels be a good investment in the long run, or is it more cost-effective to stick with your current power company? If it turns out that you’re better off with solar power but you can’t afford it, some of our partners can lease you the system for a fraction of the cost or periodic payments.

If you keep physical copies of the monthly utility, you can start by adding up the monthly payments made over the last two to three years. This is important so you don’t have to overlook your yearly power consumption, if it exceeds what you imagine. Otherwise, you could always sign in to your account or call your utility company to find out your yearly consumption. Once you have that, you have your electric kilowatt-per-hour. The simplicity of that step however only applies to you if you plan to stay connected to the grid. Look to see if there is a pattern in your power usage from an annual perspective. Sudden rises in consumption could be due to that humidifier - with the HEPA filters - you bought last year to prevent mold and help everyone in the house sleep more comfortably. Whatever the case, if you can’t explain it, factor in those kilowatt-hours so you don’t limit yourself in the end. Finally, always hold recent bills as the most accurate representation of your power needs since, the farther back in years you go, the more normal the pattern becomes. This results from the irregularities of daily use getting lost in the background of time elapsed, as well as the appliances and lights in your house being more efficient than their older counterparts.

By ‘new’, I don’t mean new construction or new-build; it’s still new if its only occupant lived there for a year or two, in which case you can ask them about their yearly consumption and go from there. If they don’t have that information, you may have to ask them to request a statement from their power company. Remember that not all homeowners use energy the same, so take what they say with a grain of salt. Another arguably more accurate way of evaluating your new home’s power demand, whether it be previously inhabited or a new-build, is by using your existing electrical consumption as the measuring standard. If the home sizes are comparable and have similar niceties, then consumption will follow suit, unless you’re using more energy-efficient appliances, bulbs, and going as far as adding solar heating and cooling (that cuts your consumption at least 50% if you incorporate general-use solar panels ), in which case you can rest on your laurels. The last and most scientific way of assessing your electrical usage is to make a load analysis. A load analysis helps you calculate electrical usage, depending on the number of powered devices in a house and their average daily consumption. To do this right, you need to list all wired devices, appliances, and lights that you know you will use in the new home. You can group them all on a room-by-room basis to avoid losing count. You can use the spreadsheet (Table 1) below and add or subtract as many rooms as you like.

Room | Quantity x | Volts x | Amps = | Watts (AC*) x | Usage (hrs/day) x | Usage (day/wk) / | 7 days x | Watts Hours (AC) |
---|---|---|---|---|---|---|---|---|

7 | ||||||||

7 | ||||||||

7 | ||||||||

7 | ||||||||

7 | ||||||||

7 |

Once you’re done reading the nameplates on the devices and filling out the table, you’ll end up with the total AC connected watts and the average daily load. But, if the nameplates include the amps without the watts, simply multiply the amps value with the volts to find the wattage (amps x volts = watts). One thing you need to watch out for when calculating the wattage of individual devices is whether or not it runs on an induction motor – a variant of electric motors. They run devices like dryers, washing machines, pumps, fans, blowers, and dishwashers. Multiplying amps with voltage will drastically overestimate the wattage. For these machines, simply multiply the wattage by 0.6 to get a more accurate load value. Sum up the values for each room and you’ll end up with the average daily load of the house.

The average load of the house will let you know what the size of a solar system should be, and whether you’ll need a battery back-up.

The size of an on-grid solar system depends primarily on the space of your home, sun peak hours, shading, and inclusion of a battery back-up. Let’s dive into the methodology behind evaluating the size of the solar array.

Fortunately for us, the grid-connected system is the easiest to plan and install. To ensure that your energy demands are always met, take the number for the average daily load and divide it by the average daily peak sun hours. Typically, 4 peak sun hours is enough to generate and utilize solar power for any home. The latest average peak sun hours for each location were published by The National Renewable Energy Laboratory (NREL) 1, which did include Virginia.

To find the right array size, let’s use an example home with an average daily load of 8 kilowatts-per-hour (kWh) with 4 peak sun hours. With these two bits of information, we can then find the daily load capacity. Dividing 8 kWh by 4 peak sun hours gives the load capacity: 2 kilowatts. But don’t go buying a solar panel kit just yet. Finally, add 22% to the size, which constitutes the factors that could hinder the photovoltaic system’s (PV) performance over time, such as excessive heat, shading, dust on components, electrical current wastage through wires, and inefficient circuitry within the PV system (fuses, inverters, charge controllers, etc.). To do this, divide 2 kW by 0.78. Adjusting the size of the solar array by 22%, then, gives us the more accurate figure: 2.6 kW. Now, you’ll need to find out the number of 285-watt modules that will meet that capacity. Simply divide the adjusted load capacity by 285 and multiply the value with 1,000. For an array made up of 285-watt modules that produces 2.6 kW, you’ll need to set up nine modules ((2.6/285) × 1000 = 9). Another thing to note, if your home is covered in shading, you may need to accommodate a larger array to counteract its reductive effect on the panels. Our partners, as all solar site assessors, typically use Sun path analysis devices that measure blocked radiation bynearby hills, trees, and other land features. If the Sun path tool points to 5% shading, your array will need to be sized up 5%.

The size of the array stays the same in a battery-backed system, but you still need to size the battery bank. Batteries are sized by the length of time a power outage usually takes. In such a scenario, most homeowners dedicate the battery to only power “critical loads”. Critical loads include essentials like water pumps, refrigerators and freezers, heating and cooling, and lights in critical living spaces, such as bathrooms and kitchens.

You might be wondering if solar panels are worth it after all. Well, that depends on your local provider’s charge of installing the system per watt. When you propagate the payoff over a 30-year period and compare it to what you would be paying on utility, you’ll have your answer. The 30-year period being the standard limit is owed to the PV system’s usual life expectancy. So, how do you compare utility payments with the investment in a PV system? The answer to that may justify investing in solar. Stick around or fill out a request for a professional to do the calculations for you, with zero-commitment.

Let’s use an example to see if purchasing and installing a solar system is worth it. Suppose your home needs 8 kWh daily and peak sun hours in your area is 4. To correctly size the system, divide your daily electrical requirement by the peak sun hours, in our case that gives us 2 kW. To size up 22% - a margin of error that accounts for equipment being faulty or exposed to the elements - divide the load capacity by 0.78 to get 2.56 kW. Assuming there is no shade blocking your panels, a local solar professional tells you they can install the PV system for $3.3 per watt. Next, take your home’s adjusted load capacity and multiply it by the proposed price per watt. In our example, 2.56 kW × $3.3 × 1000 = $8,448. Moreover, this year the federal government’s assigned a 26% rebate when purchasing a PV system, therefore you should deduct this from the final price. The Solar Investment Tax Credit (ITC) represents $2,197 of the total cost (0.26 × $8,448), and subtracting it from $8,448 equals $6,252 as the PV system’s final cost. These tax credits are set to drop 22% in 2021 and 10% in 2022, so don’t miss out on the opportunity. The solar system is worth it only if the cost of its electricity over a 30-year period beats the utility company’s traditional alternative. Stretch the example daily requirement of 8 kWh out 30 years by multiplying it by 10,950 (365 days of the year × 30 years). The result entails that the PV system will have an electrical output of 87,600 kWh over the next three decades, provided it lasts. Lastly, in getting how much you would be paying in cents by the kilowatt-hour, divide the cost your local installer gave you, after rebates, by the 30-year electrical output. With our example, dividing the installation cost of $6,252 by 87,600 kWh gives us $0.07 per kWh. If you’re interested in comparing affordable offers on installing PV systems, complete this short form to get no-obligation quotes from professionals near you.

One of the more definitive brain exercises that measure the value per buck spent on a PV system is return on investment (ROI). Conveyed in percentage form, ROI represents the annual amount of savings you make from having a PV system. It functions by dividing the value of electricity the PV system produces by its cost. Let’s do the calculations ourselves, shall we? Taking the example figure of 8 kWh that your house might need per day, we should stretch it out to a year for a workable unit of measure that the ROI calculation will require: 8 kWh × 365 days (in a year) gives 2,920 kWh of power demand. Before we proceed, we should first know the exact amount you’re currently paying in traditional electric annually. But for illustrative purposes, the table for the average cost per kilowatt-hour for all states is shown in the table below 2.

State | Dollars per Kilowatt-hour |
---|---|

Connecticut | 0.21 |

Maine | 0.17 |

Massachusetts | 0.22 |

New Hampshire | 0.2 |

Rhode Island | 0.21 |

Vermont | 0.18 |

New Jersey | 0.15 |

New York | 0.19 |

Pennsylvania | 0.14 |

Illinois | 0.13 |

Indiana | 0.12 |

Michigan | 0.15 |

Ohio | 0.13 |

Wisconsin | 0.14 |

Iowa | 0.12 |

Kansas | 0.13 |

Minnesota | 0.13 |

Missouri | 0.11 |

Nebraska | 0.11 |

North Dakota | 0.1 |

South Dakota | 0.12 |

Delaware | 0.13 |

District of Columbia | 0.13 |

Florida | 0.12 |

Georgia | 0.11 |

Maryland | 0.13 |

North Carolina | 0.11 |

South Carolina | 0.12 |

Virginia | 0.12 |

West Virginia | 0.11 |

Alabama | 0.12 |

Kentucky | 0.11 |

Mississippi | 0.11 |

Tennessee | 0.11 |

Arkansas | 0.1 |

Louisiana | 0.1 |

Oklahoma | 0.1 |

Texas | 0.11 |

Arizona | 0.13 |

Colorado | 0.12 |

Idaho | 0.1 |

Montana | 0.11 |

Nevada | 0.12 |

New Mexico | 0.13 |

Utah | 0.1 |

Wyoming | 0.11 |

California | 0.19 |

Oregon | 0.11 |

Washington | 0.1 |

Alaska | 0.22 |

Hawaii | 0.32 |

To find your household’s annual ROI from solar, let’s pick a number at random, like $0.13 per kWh, and go with it. Calculating for the yearly payments you would make towards traditional utility, multiply the example yearly 2,920 kWh we inferred earlier by $0.13 to get the annual cost of $380. If the rebated system costs $6,252, you can find ROI by dividing $380 by $6,252, which equates to 6% (($380/$6,252) × 100%) as your return on investment. Think of where you could be allocating that money to make your home more superefficient. The answer to the question of the return on investment a PV system poses is an easy, yes! But keep in mind that there are no known rebates on the horizon, post-2022, and the percentage on the federal tax credit is set to decrease in 2021, so act now by completing this short form or insert your zipcode below to speak to a local installer

- Sengupta, M. Y. (2018). Solar Resource Data, Tools, and Maps. Retrieved from NREL.gov: https://www.nrel.gov/gis/solar.html
- Administration, U. E. (2018). Annual Electric Power Industry Report. Retrieved from EIA.gov: https://www.eia.gov/electricity/annual/