Home with solar system by Maine Solar Solutions. It has an 8.01 kW array consisting of eighteen 445-watt REC solar panels with one SolarEdge SE10000H-US inverter. It is designed to produce 10,145kWh per year. (Courtesy photo)
Solar Electric and New Construction – Sizing Considerations
George Harvey
When homeowners consider installing a solar electric system on an existing home, they start off with one significant advantage – they already know their homes electricity consumption. In a building that has been occupied, the amount of electricity used has been recorded, measured in kilowatt-hours (kWh) per month. And unless there is some other change also going on at the same time, such as installation of heat pumps to replace an old oil furnace or the purchase of an electric car, the electricity production requirements for an optimal solar system are pretty much dictated.
Designing a solar electric (PV) system for a new house is a somewhat different experience. It is not usually possible to know exactly what the new home’s electricity consumption will be. If a solar electric system is being designed to offset all of the home’s electricity consumption, we will need to know how much electricity is to be used not just for lighting, but also for cooking, space heating, water heating, and a variety of other purposes.
The size of a house is a factor to be considered. The number of adults and children in the family are a factor. The lifestyle people live is also an important factor.
Sam Zuckerman of Maine Solar Solutions (MSS) gave us some insight into the approach his company uses with new construction customers. Since they do not know exactly what the home’s electricity consumption will be, they start with the data that is available, including house plans, elevations, and site plans. This allows them to determine the maximum number of panels that will fit on the roof. They then present a proposal with three different system sizes: a maximum system size, a mid-size system and a smaller more conservative system size.
“Our goal is to educate our customer so they are making an informed decision,” Zuckerman said.
The customer can choose to be conservative and install a smaller system designed for expansion or they can go with a larger system and adjust their electricity consumption to use of the available production.
Financing of the new solar system should also be considered. Federal tax credits and other financial incentives may be in place that are scheduled to be reduced or disappear, and obviously, it is best to keep these dates in mind. Clearly, it would be better to install a larger system that can take advantage of a subsidy than to install a smaller system that might not have a subsidy available when it is expanded in the future.
Also, it is a good idea to consider having the cost of a new house include the solar system when getting a mortgage. It is possible that the financing for a PV system will be considerably less expensive if it is included in the larger mortgage.
Zuckerman also pointed out that there are several considerations for designing a system that are not usually included in home owners’ thoughts. One thing to think about is the aesthetics of the system. Some people rather dislike the look of traditional solar panels that they typically see and may find that all black solar panels are more pleasing to look at.
Efficiency is another thing to consider. Solar panels do not all operate at the same efficiency. And, of course, they do not all cost the same. Some do better than others at extreme temperatures. Finding the best value on solar panels will require keeping all these factors in mind. It is not a job that most customers are prepared to tackle alone.
From the customer’s point of view, the best thing to do is to learn as much as possible before investing in a solar system. An approach to PV system sales and design like the one that is practiced by Maine Solar Solutions is one that is itself designed to make the solar design as clear as possible to customers.
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