How to Properly Size Your Home Solar System
An undersized solar system leaves you paying more to JPS than necessary, while an oversized system wastes money on panels that generate energy you cannot efficiently use or sell. Proper sizing is the foundation of a solar installation that delivers maximum financial return and meets your household's energy needs.
Analyzing Your Electricity Consumption
Pull together twelve months of JPS bills and calculate your average monthly consumption in kilowatt-hours. Look for seasonal patterns since air conditioning usage often spikes during Jamaica's hottest months from June through September. Note your highest consumption month because your system should be designed to handle your peak needs, not just your average. A household consuming an average of 900 kilowatt-hours per month with peak months reaching 1,200 kilowatt-hours needs a system sized for productive output that addresses the higher figure.
Calculating Required System Capacity
In Jamaica, each installed kilowatt of solar capacity produces approximately 115 to 135 kilowatt-hours per month, depending on location, roof orientation, and shading. To offset 900 kilowatt-hours of monthly consumption, you would need approximately 7 to 8 kilowatts of installed capacity. However, since net billing credits for exported energy are valued below the retail rate, it is often more cost-effective to size your system to cover 80 to 90 percent of your total consumption rather than 100 percent, ensuring that most of your production is consumed directly.
Roof Space Constraints
Each kilowatt of modern monocrystalline solar panels requires approximately 5 to 6 square meters of unobstructed roof space. A 7-kilowatt system therefore needs roughly 35 to 42 square meters. Account for setbacks from roof edges, areas shaded by trees or adjacent structures, and space for walkways required by building codes. If your available roof space limits the system size below your target capacity, higher-efficiency panels can extract more power from the same area, though at a higher cost per watt.
Planning for Future Energy Needs
Consider how your electricity consumption might change over the next five to ten years. Are you planning to add air conditioning to additional rooms, install a pool pump, or purchase an electric vehicle? Building headroom into your system design now is far cheaper than adding panels later, which may require additional inverter capacity and a new JPS application. Even if you do not install extra panels immediately, choosing an inverter with spare capacity and leaving roof space for future expansion keeps your options open.
Getting Quotes and Comparing Proposals
Request proposals from at least three licensed solar installers in Jamaica. Compare them on system size, panel brand and efficiency, inverter brand and features, warranty terms, projected energy production, and total installed cost. Be wary of proposals that promise unrealistically high production figures or use the cheapest available equipment. Your solar system will operate on your roof for 25 years or more, so quality components and professional installation are worth the premium.
