Comprehensive month-by-month PVGIS data for plug-in solar across four UK regions. Annual patterns, self-consumption dynamics, and what each season means for your savings.

Plug-in Solar UK Monthly Performance Guide: What to Expect All Year

This is the definitive guide to plug-in solar generation patterns across the UK. Using PVGIS European solar radiation data, we show you month-by-month expectations for four UK regions, helping you predict annual output and plan when to shift your consumption for maximum savings.

800W System: Monthly Generation by Region

The data below represents a typical 800W plug-in solar system (two 400W panels in series, south-facing, 35° tilt) under real European atmospheric and cloud conditions:

London (South-East England)

Month	Daily Avg	Monthly Total	Self-Consumption Potential	Key Insight
January	0.8 kWh	25 kWh	Very low (winter load mismatch)	Minimal value without battery
February	1.1 kWh	31 kWh	Low (demand doesn't align)	Still winter; patience required
March	2.4 kWh	75 kWh	Moderate (12-2pm window)	Inflection point; output triples
April	3.6 kWh	108 kWh	Good (longer daylight)	Spring acceleration continues
May	4.5 kWh	140 kWh	Excellent (shift loads to noon)	Peak self-consumption season begins
June	5.0 kWh	150 kWh	Excellent (export problem starts)	Need battery or acceptance of waste
July	5.2 kWh	161 kWh	Excellent (but excess wasted)	Highest output month
August	4.8 kWh	149 kWh	Excellent (leaf shade emerging)	Still excellent; monitor for shade
September	3.5 kWh	105 kWh	Good (leaf shade increases)	Autumn decline begins
October	2.2 kWh	68 kWh	Moderate (sun angle drops fast)	Rapid descent into winter
November	1.3 kWh	39 kWh	Low (dark mornings/evenings)	Winter pattern establishes
December	0.7 kWh	22 kWh	Very low (shortest day)	Minimum generation point
ANNUAL TOTAL	2.9 kWh avg	1,073 kWh	—	—

Manchester (North-West England)

Month	Daily Avg	Monthly Total	Notes
January	0.6 kWh	19 kWh	Higher cloud cover than south
February	0.8 kWh	23 kWh	—
March	1.9 kWh	59 kWh	Turning point still occurs
April	2.9 kWh	87 kWh	—
May	3.8 kWh	118 kWh	—
June	4.2 kWh	126 kWh	Slightly lower than London
July	4.4 kWh	136 kWh	—
August	4.0 kWh	124 kWh	—
September	2.9 kWh	87 kWh	—
October	1.8 kWh	56 kWh	—
November	1.0 kWh	30 kWh	—
December	0.5 kWh	16 kWh	—
ANNUAL TOTAL	2.4 kWh avg	881 kWh	~18% lower than London

Edinburgh (Scotland)

Month	Daily Avg	Monthly Total	Notes
January	0.4 kWh	12 kWh	Latitude effect: very low winter
February	0.6 kWh	17 kWh	—
March	1.6 kWh	50 kWh	March jump still pronounced
April	2.5 kWh	75 kWh	—
May	3.6 kWh	111 kWh	Similar to Manchester May
June	4.0 kWh	120 kWh	Summer peak lower due to latitude
July	4.1 kWh	127 kWh	—
August	3.8 kWh	118 kWh	—
September	2.6 kWh	78 kWh	—
October	1.5 kWh	47 kWh	—
November	0.8 kWh	24 kWh	—
December	0.3 kWh	9 kWh	Extreme minimums at high latitude
ANNUAL TOTAL	2.0 kWh avg	718 kWh	~33% lower than London

Cardiff (Wales)

Month	Daily Avg	Monthly Total	Notes
January	0.7 kWh	22 kWh	Intermediate between London/Manchester
February	1.0 kWh	28 kWh	—
March	2.2 kWh	68 kWh	—
April	3.4 kWh	102 kWh	—
May	4.2 kWh	130 kWh	—
June	4.7 kWh	141 kWh	—
July	4.9 kWh	152 kWh	—
August	4.5 kWh	139 kWh	—
September	3.2 kWh	96 kWh	—
October	2.0 kWh	62 kWh	—
November	1.2 kWh	36 kWh	—
December	0.6 kWh	19 kWh	—
ANNUAL TOTAL	2.7 kWh avg	995 kWh	~7% lower than London

400W Single-Panel System: Quick Reference

For a 400W system, divide the above figures by 2. For example:

London 400W: ~537 kWh annually (2.9/2 × 365 ≈ 537)
Manchester 400W: ~440 kWh annually
Edinburgh 400W: ~359 kWh annually
Cardiff 400W: ~498 kWh annually

Annual Pattern Analysis

High Generation Period (May–August): 40% of Annual Output

Summer dominates. Four months generate ~430 kWh (40% of London's 1,073 annual). This is when you experience real savings—or real export waste if you lack battery storage.

Implication: If you can only install battery storage, summer is when it matters most.

Transitional Periods (March–April, September–October): 30% of Annual Output

Spring and autumn are the sweet spots for self-consumption. Generation aligns reasonably with typical household consumption patterns. No excess waste, no winter shortage.

Implication: If your job is remote or flexible, spring/autumn are the best seasons for load-shifting.

Low Generation Period (November–February): 15% of Annual Output

Four months generate just ~115 kWh (11% of annual). This doesn't mean winter is useless, but it's where plug-in solar's limitations become obvious.

Implication: Winter payback periods are terrible. Justify winter plug-in solar only if you have battery storage or genuine daytime consumption (shift work, home heating).

Self-Consumption by Season

Understanding when your generation aligns with your consumption is critical:

Summer (June–August)

Generation peak: 10 am–3 pm, reaching 1.5+ kW
Typical consumption: 0.3–0.8 kW (office/school mode)
Problem: 30–50% of generation wasted as export
Solution: Add battery or shift loads (laundry, dishwasher at noon)

Spring/Autumn (March–May, September–October)

Generation peak: 10 am–2 pm, reaching 1.0–1.5 kW
Typical consumption: 0.5–1.0 kW (partially at home)
Outcome: 50–70% self-consumption naturally
Bonus: Little action needed; systems work well

Winter (November–February)

Generation peak: 11 am–1 pm, reaching 0.2–0.4 kW
Typical consumption: 0.5–1.0 kW (heating, extended daytime)
Problem: Very little generation; nearly all self-consumed but insufficient
Solution: Battery becomes essential for any winter value

Monthly Tips for Maximising Output

Month	Action	Benefit
January–February	Keep panels clean of winter grime	+10% (3–5 kWh)
March	Adjust angle to 35° if adjusting from winter; inspect shade patterns	+15% on sunny days
April–May	Shift laundry, dishwasher to 11 am–1 pm	+25% self-consumption value
June–August	Consider battery if not already owned; keep angle at 25–30° if adjustable	Prevents 30–50% waste
August–September	Monitor for new shade from leafy trees; trim overhanging branches	Prevents 10–20% losses
October	Steepen angle toward winter (~50°) if adjustable	+15% in November
November–December	Ensure panels are clean; verify monitoring is connected	+15% from cleanliness

Regional Variation Summary

Region	Annual Output (800W)	Relative to London
London (South-East)	1,073 kWh	100%
Cardiff (Wales)	995 kWh	93%
Manchester (North-West)	881 kWh	82%
Edinburgh (Scotland)	718 kWh	67%

Key insight: Northern UK systems generate 30–35% less annually, but the seasonal pattern is identical. March still triples from January everywhere.

From Data to Actual Savings

Annual output is one thing; actual savings depend on:

Self-consumption rate: Exporting wastes money (you earn 5–10p/kWh, pay 20–25p/kWh)
Electricity price: Current rates are ~25p/kWh; inflation changes ROI
Battery ownership: Shifts winter/evening value up significantly
Consumption profile: Work from home? Shift work? Great for self-consumption.

Rough savings estimate (London, 1,073 kWh/year, 70% self-consumption, 25p/kWh):

1,073 × 0.70 × £0.25 = £188/year in electricity avoided
Payback period on £800 system: ~4 years

With battery storage and optimised load-shifting, payback drops to 2–3 years.

What to Expect on Specific Days

To help you intuition-check this data in real time:

Sunny January day: 2–3 kWh (all day), concentrated 10 am–2 pm Sunny April day: 5–6 kWh (all day), peak 11 am–2 pm at 1.5–2 kW Sunny July day: 7–8 kWh (all day), peak 11:30 am–2:30 pm at 2.0–2.5 kW Overcast day (any month): 30–40% of sunny-day output Rainy day (any month): 10–20% of sunny-day output or zero

Using PVGIS to Verify for Your Location

These tables are based on PVGIS (pvgis-pvwatts.ec.europa.eu), a free tool you can use for your exact postcode:

Visit pvgis-pvwatts.ec.europa.eu
Pan to your UK roof on the map
Click your location
Enter system details: 800W nominal, 35° tilt, south-facing
Download the monthly CSV to see your precise forecast

PVGIS data is accurate to within ±10% based on 20+ years of satellite weather records.

Cross-Links: Understanding Your System Year-Round

Confused about winter performance? See January generation reality
Ready to optimise summer? See summer tips
Planning a spring install? See when spring turns good
Deciding on system size? See single vs dual panels
Preparing for winter? See autumn maintenance

The Bottom Line

Annual output for an 800W system ranges from 718 kWh (Scotland) to 1,073 kWh (South-East). The seasonal distribution is skewed heavily toward summer: 40% of annual generation occurs in just four months, whilst winter's four months generate only 11%.

Real-world savings depend on self-consumption alignment and battery ownership. Without battery storage, summer plug-in solar wastes 30–50% of generation, but spring and autumn are excellent. Winter is nearly useless without battery or specific consumption patterns.

Use this guide as a reference each month, and compare your actual generation (from your monitoring app) against these PVGIS expectations. You'll quickly develop intuition for when your system is performing normally and when something is amiss (shade, dirty panels, monitoring failure).