St Mary solar guide

A productive coast, with a cloudier and more varied interior.

St Mary’s north-coast edge performs better than much of its hilly interior. The parish remains suitable for solar, but generic Jamaica-wide output claims can overstate some locations.

Local data guide · published 31 August 2026

Try a system size

What would that mean on a roof?

These figures estimate electricity from the panels, not money saved. A kWh is one unit of electricity on your bill; kW describes the panel system’s rated size. Your savings depend on when you use that electricity, whether you store it in a battery and whether you send any to JPS Jamaica.

Typical year

7,603 kWhabout 634 kWh per month on average

Middle half of locations

7,480–7,778 kWhDifferences between locations; your roof can change the result

Strongest month

July · 699 kWhLong-term average, not a forecast

Weakest month

December · 548 kWhAbout 22% below July

Colour map of modelled annual solar electricity output across St Mary. — **Annual solar electricity across St Mary**Each square is approximately 1 km. The stepped edge shows the source resolution rather than pretending the estimate is more precise.

About 1,310About 1,640 kWh/kWp

The parish is not one number

The coastal edge is stronger. Interior hills create the spread.

The strongest mapped cells sit along sections of the north coast around Port Maria and toward the western boundary. Output becomes lower across interior and southeastern hills.

St Mary also has a more noticeable seasonal dip late in the year, so annual output should not be divided by twelve and treated as a monthly promise.

Cells analysed: 762
Central geographic range: 1,496–1,556
Typical variation: About ±2%

Month by month

How does solar output change through the year?

July is strongest in the long-term model. December produces about 78% of that output, so the annual figure should not be treated as twelve identical months.

572Jan

588Feb

694Mar

673Apr

645May

653Jun

699Jul

685Aug

657Sep

634Oct

554Nov

548Dec

Estimated monthly generation in kWh for the selected system size. Hover, tap or focus a bar for its detailed value. The figures are long-term estimates, not a weather forecast.

View the monthly figures as a table

Month	Per installed kW	5 kW system
January	114.4 kWh	572 kWh
February	117.7 kWh	588 kWh
March	138.8 kWh	694 kWh
April	134.5 kWh	673 kWh
May	128.9 kWh	645 kWh
June	130.6 kWh	653 kWh
July	139.8 kWh	699 kWh
August	136.9 kWh	685 kWh
September	131.4 kWh	657 kWh
October	126.9 kWh	634 kWh
November	110.9 kWh	554 kWh
December	109.7 kWh	548 kWh

Before asking for quotes

Questions worth asking in St Mary.

Where do hills and trees block the sun?A property can lose the early or late part of the solar day even when its annual resource cell looks reasonable. Request a measured shade assessment.
Can the roof and fixings tolerate persistent moisture?Use compatible metals, properly rated enclosures and waterproof penetrations; corrosion risk is not limited to homes directly on the coast.
How will hurricane loads reach the structure?Rails and brackets only work when attached into sound framing or structure with spacing appropriate to the exposed site.
Is the estimate seasonally honest?Ask the installer for monthly production, not only an annual total, and compare the weaker November–December period with the household’s needs.

Use the Jamaica panel and roof guide to test the mounting and equipment answers in a quotation.

Generation is not the bill

A 5 kW system making 634 kWh a month will not automatically erase the same-sized bill.

Timing decides value

Solar used in the home avoids the retail cost of a JPS Jamaica unit. Surplus sent through net billing receives a much lower export credit.

A battery moves energy

A battery can carry daytime generation into evening use and provide outage cover, but it does not make the panels generate more.

Your roof changes the result

Shade, direction, heat, dirt, cable losses and equipment choices move a real installation away from the parish benchmark. Use the panel guide to test those roof assumptions.

How we calculated this

Where do these estimates come from?

We use long-term sunshine data to estimate panel output across the parish. These are planning averages, not a forecast for your roof. Shade, roof direction and equipment can change the result.

See the data, calculation and source assumptions

We selected the 762 Global Solar Atlas PVOUT grid cells whose centres fall inside the St Mary parish boundary, then calculated the annual mean, central 50% range and monthly means.

The source models a free-standing crystalline-silicon system at optimum fixed tilt. It is useful for parish comparison and early planning, not a guarantee for a particular roof.

Solar source: Global Solar Atlas 2.0 PVOUT
Source years: 1999–2018 long-term average
Spatial resolution: 30 arc-seconds, approximately 1 km
Calculation: Jamaica Solar Check parish aggregation

Solar data obtained from Global Solar Atlas 2.0, developed and operated by Solargis on behalf of the World Bank Group with ESMAP funding. Source data © 2019 Solargis, CC BY 4.0. Parish calculations and colour map are adaptations by Jamaica Solar Check; the source organisations do not endorse this site. Boundary geometry: geoBoundaries JAM ADM1, sourced from OpenStreetMap/Wambacher, CC BY-SA 2.0.