Portland solar guide

Solar works here—but a Jamaica-wide average is misleading.

Portland has the lowest parish average in this dataset and the widest practical coast-to-mountain difference. That makes local modelling more valuable, not solar pointless.

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

7,006 kWhabout 584 kWh per month on average

Middle half of locations

6,649–7,407 kWhDifferences between locations; your roof can change the result

Strongest month

July · 684 kWhLong-term average, not a forecast

Weakest month

December · 463 kWhAbout 32% below July

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

About 1,140About 1,590 kWh/kWp

The parish is not one number

The coastal strip is stronger. Mountain terrain pulls the average down.

The map is stronger along parts of the north coast around Port Antonio and Buff Bay, then falls across the wetter, higher interior toward the Blue and John Crow Mountains.

A good coastal roof can outperform the parish headline, while a shaded mountain site may sit well below it. Portland is exactly where a roof-specific shade and production study earns its cost.

Cells analysed: 1,017
Central geographic range: 1,330–1,481
Typical variation: About ±6%

Month by month

How does solar output change through the year?

July is strongest in the long-term model. December produces about 68% of that output, so the annual figure should not be treated as twelve identical months.

491Jan

513Feb

615Mar

615Apr

615May

629Jun

684Jul

672Aug

648Sep

588Oct

472Nov

463Dec

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	98.2 kWh	491 kWh
February	102.5 kWh	513 kWh
March	123.0 kWh	615 kWh
April	122.9 kWh	615 kWh
May	123.0 kWh	615 kWh
June	125.9 kWh	629 kWh
July	136.9 kWh	684 kWh
August	134.4 kWh	672 kWh
September	129.6 kWh	648 kWh
October	117.6 kWh	588 kWh
November	94.5 kWh	472 kWh
December	92.7 kWh	463 kWh

Before asking for quotes

Questions worth asking in Portland.

Has shade been measured across the year?Mountain ridges, dense vegetation and local cloud make a quick visual inspection inadequate. Ask for the shade assumptions behind every production estimate.
Can the equipment handle moisture?Choose suitable enclosure ratings, cable entries and corrosion-resistant fixings, and keep inverters and batteries away from rain and persistent damp.
Is vegetation maintenance realistic?Leave safe access and agree who is responsible for keeping trees from changing the array’s solar window after installation.
Does the proposal use Portland data?Reject an islandwide kWh-per-kW promise. Compare the installer’s monthly forecast with this local range and ask why it is higher or lower.

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 584 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 1,017 Global Solar Atlas PVOUT grid cells whose centres fall inside the Portland 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.