Plug-in Solar: What to Expect in Year One

Your plug-in solar system is up and running. You have survived the first week, set up monitoring, and started shifting loads. Now the question becomes: what does a full year actually look like?

This guide covers every month, based on real PVGIS data for an 800W south-facing system in central England (Birmingham, 52.5°N). Your numbers will vary by location, angle, and shading, but the patterns are universal.

The Annual Overview

An 800W plug-in solar system in a typical UK location generates approximately 700-850 kWh per year. That is enough to power a washing machine, dishwasher, and fridge-freezer for the year, or offset roughly 25-30% of average household electricity consumption.

But that generation is not evenly distributed. Summer months produce 3-5 times more than winter months. Understanding this pattern is the key to realistic expectations and sustained satisfaction with your system.

January: The Quiet Month

Expected generation: 25-35 kWh (0.8-1.1 kWh per day)

January is the lowest-performing month. Days are short (roughly 8 hours of useful daylight), the sun is low in the sky, and cloud cover is frequent. On the worst days, you might generate just 0.3 kWh. On the best clear days, 2 kWh is possible.

What to expect:

• The system IS working, even if the numbers seem disappointing
• Generation peaks between 11am and 1pm
• Any solar generation in January is a bonus — it reduces your import during the most expensive time of year

Common question: "Is my system broken? It's barely generating anything."

No. This is completely normal. A 800W system simply cannot overcome short days and low sun angles. If your monitoring app shows any generation during daylight hours, the system is working. For context, see our January generation guide.

February: The First Glimmers

Expected generation: 35-50 kWh (1.3-1.8 kWh per day)

February is noticeably better than January. Days are lengthening by 2-3 minutes per day, and the sun is climbing higher. By late February, you will see generation start earlier and last longer.

What to expect:

• A 40-50% improvement over January
• The occasional clear day producing 3+ kWh
• A psychological boost after the winter doldrums

March: Spring Arrives

Expected generation: 55-70 kWh (1.8-2.3 kWh per day)

March is when things get interesting. The clocks change on the last Sunday of March, and suddenly your system has an extra hour of evening generation. The spring equinox means 12 hours of daylight, and the sun is high enough to produce meaningful output.

What to expect:

• Daily output starts to feel worthwhile
• Load-shifting becomes more impactful — enough generation to run a washing machine cycle most days
• Clear spring days can produce 4-5 kWh

Read our detailed spring performance guide for more.

April: The Ramp-Up

Expected generation: 75-95 kWh (2.5-3.2 kWh per day)

April is often the month that makes new solar owners smile. Generation roughly doubles compared to February. The combination of longer days, higher sun angle, and (relatively) clearer skies means consistent daily output.

What to expect:

• 3-4 kWh on most days
• Peak output approaching 600-800W on clear afternoons
• Your electricity bill starts to show a noticeable reduction
• Some export on sunny days when you are not home

May: Nearly There

Expected generation: 90-110 kWh (2.9-3.5 kWh per day)

May typically delivers near-peak generation. Days are long (15-16 hours of daylight) and the sun is high. May often outperforms June in the UK because it tends to have clearer skies — June can be cloudier than people expect.

What to expect:

• Consistent 3-4 kWh days with 5+ kWh peaks
• More generation than you can easily self-consume
• Export becomes a regular occurrence unless you are actively load-shifting
• The question shifts from "am I generating enough?" to "how do I use more of what I generate?"

June: Peak Season Begins

Expected generation: 95-115 kWh (3.2-3.8 kWh per day)

June has the longest days (over 16 hours in southern England, nearly 18 in northern Scotland) and the highest sun angle. Generation starts before 6am and continues past 9pm.

What to expect:

• Near-maximum daily output
• Generation often exceeding household daytime consumption
• Significant export if you are not aggressively load-shifting
• The panels feel like they are working hard — because they are

July: The Peak

Expected generation: 95-110 kWh (3.1-3.5 kWh per day)

July is typically the highest-generation month, driven by long days and summer sun. Interestingly, very hot days can slightly reduce output — solar panels are less efficient above 25°C. The UK rarely gets hot enough for this to matter much, but you might notice a slight dip on the rare 30°C+ day.

What to expect:

• Consistent high output
• Peak instantaneous output of 700-800W during midday
• On very hot days, output may drop 5-10% compared to a 20°C day
• Generation from early morning to late evening

August: Still Strong

Expected generation: 85-100 kWh (2.7-3.2 kWh per day)

August remains excellent. Days shorten slightly but remain long. The sun angle begins to drop but is still high. Generation is typically 85-95% of July levels.

What to expect:

• Very similar to July with marginal decline
• The psychological mid-point of the solar year
• Cumulative generation since January should now be 500-600 kWh

September: The Gentle Decline

Expected generation: 60-80 kWh (2.0-2.7 kWh per day)

September marks the transition from summer to autumn. The equinox brings equal day and night, and the sun drops noticeably lower in the sky. Generation is still useful but clearly declining.

What to expect:

• Noticeable reduction from August
• Generation increasingly concentrated in the 10am-3pm window
• Less export — your self-consumption ratio actually improves because generation better matches consumption
• Still enough to run major appliances during the day

October: Autumn Sets In

Expected generation: 40-55 kWh (1.3-1.8 kWh per day)

October is the mirror of March. Clocks go back on the last Sunday, losing an hour of evening generation. Cloud cover increases and the sun is low.

What to expect:

• A clear step-down from September
• Good days are still possible — 3 kWh on a clear October day
• Bad days might produce less than 1 kWh
• The savings become less dramatic but the system is still contributing

November: The Slide

Expected generation: 25-35 kWh (0.8-1.2 kWh per day)

November is nearly as low as January. Short days, low sun, frequent cloud. The system is generating, but only modestly.

What to expect:

• Similar output to January
• Generation window narrows to 9am-3pm
• Every unit generated is valuable — electricity prices are at their highest in winter

December: The Lowest Point

Expected generation: 20-30 kWh (0.6-1.0 kWh per day)

December is the lowest month. The shortest day (21 December) has roughly 7.5 hours of daylight in southern England. Combined with low sun angles and frequent cloud, daily generation can be as low as 0.2 kWh.

What to expect:

• The system IS still working
• Even 0.5 kWh per day saves you 15p at 30p/kWh — it adds up
• Clean the panels if you have not already — winter dirt and grime reduce output more when every photon counts

The Export Problem

From April to August, your system will regularly generate more than you consume during the day. This surplus goes back to the grid. Under most standard tariffs, you receive nothing for this exported electricity.

This is the "export problem" — you are generating free electricity, but unless you use it yourself, the financial benefit is zero.

Solutions:

1. Load-shifting — run appliances during peak generation. This is the cheapest and most effective solution.
2. Smart export tariffs — some suppliers (notably Octopus Energy) offer export payments of 4-15p per kWh. Worth investigating if your export is significant.
3. Battery storage — stores daytime generation for evening use. Currently excluded from the interim product specification for plug-and-play systems, but can be added separately by an electrician.

For a detailed look at export options, see our export guide.

Should You Adjust the Panel Angle?

A common first-year question. The optimal angle varies by season:

• Summer: A shallow angle (20-25°) captures more of the high summer sun
• Winter: A steep angle (50-60°) captures more of the low winter sun
• Year-round optimum: 35° is the best compromise for the UK

Our advice: Set your panels to 35° and leave them. The marginal gain from seasonal adjustment is small (5-10%) and the hassle of climbing a ladder every few months is not worth it for most people.

If your panels are flat (0°), however, tilting them to even 15-20° makes a meaningful difference. See our panel angle guide for the full analysis.

Year One by the Numbers

For an 800W system, south-facing at 35°, in central England:

• Total annual generation: 750-850 kWh
• Best month: July (95-110 kWh)
• Worst month: December (20-30 kWh)
• Self-consumption rate (with load-shifting): 50-70%
• Annual savings (at 30p/kWh, 60% self-consumption): £135-155
• Annual savings (with export payments at 7.5p/kWh): £175-210

These numbers assume no battery storage. Adding a battery can push self-consumption above 80%, increasing savings to £200-280 per year.

For a personalised estimate, use our savings calculator.

What to Watch For

Over year one, keep an eye on:

• Panel degradation — modern panels degrade at 0.3-0.5% per year. You will not notice this in year one.
• Dirt and debris — clean panels once or twice a year. Rain does most of the work, but bird droppings and tree pollen can accumulate. See our maintenance guide.
• Inverter reliability — micro-inverters are solid, but watch for error codes in your monitoring app.
• Shading changes — trees grow, neighbours build extensions. If a new shadow appears over your panels, it is worth investigating.

Our detailed year 2-3 maintenance guide covers long-term care. But for now, enjoy your first year. You are generating your own electricity, and that feeling does not get old.