Twenty six answers

We take your annual consumption in kilowatt hours from twelve months of bills, then divide by the specific yield for your roof. In the Raleigh area a well oriented, unshaded array returns roughly 1,300 to 1,400 kWh per installed kW per year as a sample range. A home using 12,000 kWh a year therefore needs around 9 kW DC before we adjust for shading and roof area.

Kilowatts measure rate, kilowatt hours measure quantity. Your array is quoted in kW because that is its maximum rate of generation. Your bill is in kWh because that is the quantity of energy you used. A 9 kW array does not produce 9 kWh, it produces roughly 12,000 kWh over a year.

Divide the system size in watts by the module wattage. A 9 kW system built with 440 W modules is 21 modules. At about 21.5 square feet each that is roughly 450 square feet of panel, and you need 15 to 20 percent more roof than that once fire setbacks and walkways are allowed for.

Because sizing follows consumption and roof, not house size. A household with a heat pump, an electric water heater and an EV can use three times the energy of a similar house with gas heat and one car.

Sometimes, in spring and autumn. That surplus goes to the grid under your utility's export arrangement. What it is worth to you depends on your rider, which is why we model export credit separately rather than assuming one for one.

No, but it helps. In this latitude a true south plane is the reference. East or west facing planes typically return roughly 12 to 18 percent less annual energy for the same array. North facing planes we decline, because the loss is severe enough that the money is better spent elsewhere.

Around 30 degrees, which is close to a 7:12 pitch, maximises annual yield at this latitude. The curve is flat though: anything between roughly 15 and 40 degrees is within a few percent of optimal, so pitch is rarely the deciding factor.

We measure it as total solar resource fraction, the share of ideal annual irradiance a plane actually receives. A plane at 85 percent loses 15 percent of its potential. We publish this figure per plane and normally advise against panels on any plane below about 70 percent.

Replace it first. An architectural shingle roof runs 20 to 25 years in this climate, so fifteen years in leaves under half its life. Removing and reinstalling an array later costs thousands and buys you nothing.

A residential array adds roughly 2.5 to 3.5 pounds per square foot, which almost every modern roof handles. Older framing with 2x4 rafters at wide spacing occasionally needs reinforcement, which we identify from the attic at the site check.

Modules are tested to withstand one inch hail at around 50 miles per hour and the mounting is engineered for the local wind zone. Your homeowner policy normally covers the array as a building improvement, and we provide the documentation your insurer will ask for.

Not on its own. A grid tied inverter is required to shut down when the grid goes down, so that it cannot energise lines that a crew believes are dead. Backup needs a battery with an islanding transfer switch.

Usable kilowatt hours divided by your backed up load in kilowatts. One 13.5 kWh module carrying an 800 W average load runs about seventeen hours. The same module carrying 2.5 kW runs about five. That is why we build a load schedule instead of quoting a runtime.

Sometimes, if the service size and the transfer rating allow it and you accept the cost. Most households get better value from a critical loads subpanel that leaves the range, dryer and water heater on the unbacked side.

Yes, if you have an array. The system runs the house and recharges the battery from generation while blocking export. That is what turns a one day battery into a multi day one.

A generator gives you unlimited runtime as long as you have fuel, and it needs maintenance, fuel storage and a monthly exercise cycle. A battery is silent, instant and maintenance free but finite. Households that lose power for hours prefer batteries. Households that lose it for days in rural areas often still want a generator.

Net cost after credits, divided by first year savings, with escalation and degradation applied year by year. Net cost is the contract price less any credit you can actually use. First year savings is production multiplied by what each kilowatt hour is worth to you, which is not the same as your headline rate once export credit is treated properly.

For a purchased residential system in this region our models typically land between nine and thirteen years, as a sample range, depending on consumption, shading and whether storage is included. Storage lengthens payback and buys resilience instead.

We guarantee production against the model, within 10 percent, because production is what we control. We cannot guarantee savings, because savings depend on future utility rates and on how you use energy, and anyone promising otherwise is guessing.

It reduces federal income tax owed for the year the system is placed in service. It is not a rebate and not a discount on the invoice. If you owe less tax than the credit, the remainder generally carries forward. Confirm your own position with a tax professional.

Lower up front, higher over the life, and the tax credit goes to the system owner rather than to you. Leases suit households without the tax appetite or the capital. We will tell you plainly which case you are in.

Typically eight to fourteen weeks from signed contract to permission to operate. Install itself is one to two days. The rest is design, permitting and the utility interconnection review, and those timelines belong to other organisations.

The utility's written authorisation to energise and export. Until PTO lands the system stays off, even if it is physically complete and inspected. It is the single most common source of the last delay.

We do. Building and electrical permits with your authority having jurisdiction, the interconnection application with the utility, and the HOA architectural submission where one applies.

Twenty five years on our mounting workmanship and flashing, module and inverter warranties per the equipment we install, and ten years on battery modules. All equipment warranties are registered in your name at commissioning and copies go in your handover pack.

An owned system transfers with the property and generally supports the sale. A leased system requires the buyer to assume the agreement, which adds a step to closing. We provide the transfer documentation either way.