How to Assess Your Building for Solar Hot Water
Solar hot water systems use the sun’s energy to heat your water. Considering the rising costs of natural gas, the increasingly stringent building energy codes, and the government’s mega thermal rebates and incentives programs, solar hot water systems have become the hottest (pardon the pun) sustainable solution on the market today.
However, not all solar hot water projects are created equal. Unlike solar PV systems, every solar hot water system is different. A solar hot water system may not always make financial sense for a particular property because of various layout factors. “Each solar thermal project site is always unique with its own set of conditions and factors. Ensuring that an engineer is specifically experienced in solar thermal system design is critical to optimizing both the system performance and financial payback,” says William Chen, COO of the San Diego solar thermal company, Adroit Energy Inc. Although many thermal installers have the craftsmanship to find a solution, here are 5 things to look for on your property if you are considering a solar hot water system:
The roof is usually the first thing property owners evaluate before calling a solar thermal installer. Even though a nice, flat, unobstructed roof is the best case scenario for a solar thermal system, this may not always be the case for a particular property. Many modern buildings are designed with roofs divided into small sections featuring various roof slopes. Solar hot water panels may not be able to fit in the available space. Moreover, in this situation, city permit requirements may become an issue. Although these architectural roof styles look nice, this design may prohibit a developer from saving money with a solar thermal system.
If there is land around the building, a ground mount or trellis system may be a better option.
2.) Boiler Location
In many cases, the solar hot water system’s panels on the roof are piped to a solar hot water tank that pre-heats your existing boiler. The more distance the installer needs to pipe in order to connect these three elements, the more expensive the project may become.
Ideally, the boiler is located on the roof. In this situation, minimal piping will be needed to connect your current system to the panels. If your boiler is in a closet or mechanical room, there needs to be available space next to your current boiler for the new solar hot water tank. Installers can often build the solar hot water tank on a concrete slab, or inside small structure, outside the mechanical room.
If you own a high-rise with a mechanical room in the basement, piping becomes more costly. Depending on the number of levels between the mechanical room and the roof, the simple physics of water pressure and gravity may prevent a solar hot water system from functioning. Your local thermal installer will be able to tell you if there is too much distance in order for the system to work efficiently.
3.) Multiple Boilers
If a property has multiple hot water heaters, a solar hot water system may not make financial sense. This point is especially true for multifamily housing developments. If each apartment has an individual hot water heater, the material and costs may increase substantially. The price goes up even more if the residents pay individual gas bills. Often, a solar thermal ICS unit or a thermosiphon could be an excellent and affordable solution.
4.) Building height
Usually, low rise buildings with flat roofs do not have issues with the roof space required to efficiently run a solar hot water system. However, low rise buildings may be more susceptible to shading from trees or high-rises.
As far as high-rises are concerned, as buildings get taller, the ratio of the increased hot water demand to available roof area can drop very quickly. There could also be complications for a tall building with a mechanical room in the basement. As previously explained, more piping equals higher costs.
In these instances, a solar thermal installer may suggest a solar façade, carport, or trellis structure as an alternative.
A property with a flat, southeast to southwest facing roof could be the perfect candidate to save money with a solar hot water system. However, shading is a huge factor that can greatly reduce your system’s efficiency and payback.
If a tree or another building is shading a thermal collector, that particular collector will not work efficiently. Also, if you own a low-rise building positioned among high-rises, shading could also be an issue. Shading is even more problematic in solar photovoltaic systems. If one PV panel gets shade, the entire row of panels connected to it will also substantially slow down.
In many circumstances, property owners are willing to cut and trim the trees in order to gain the sun’s benefits. A qualified installer will use a device to measure your shading and discuss your options.
If you believe your property may qualify for a solar hot water system, send us an email at email@example.com. We’ll contact you and evaluate your property together.