Solar Thermal Installations

Q: What’s the size and weight of a DHW PV panel?
A: They vary, but most are around 4′x 8′ and weigh between 100lbs and 135lbs (plus about 3lbs. with fluid).

Q: How many panels are normally required?
A: For domestic hot water needs (showers, laundry, dishwashing, etc.), an installation usually comprises two panels for a household of two people; for additional heating applications, such as radiant floor heating, more panels are required. Installations using the more efficient evacuated-tube panels require fewer panels.

Q: How should panels be positioned on rooftops?
A: The ideal angle from horizontal is 45°. The panels should be angled a little west of south (194° or further west), to avoid morning haze and to better accommodate the generally more prevalent use of power later in the day.

Q: Might installation and use increase roof leaks?
A: It’s unlikely, since arrays are bolted to rafters, not plywood, and flashing and caulking is done at time of installation.

Q: Wouldn’t the array interfere with roof maintenance or replacement?
A: If roof shingles are over ten years old, it would be sensible to re-shingle before the installation.

Q: Will my roof need reinforcement?
A: Roofs must be appropriately up to code for weight bearing, but should not need reinforcing.

Q: What kind of maintenance do the panels need?
A: The non-toxic glycol fluid generally used as a heat transfer substance needs checking and possibly replacing every five years.

Q: How much will the panels heat my water?
A: Depending on the type (flat plate vs. evacuated-tube) and number of collectors and size of tank, water temperatures of 110° - 180° can be achieved.