A 3-bedroom house with an east/west roof has panels on both sides of the ridge. You lose about 19% of total yield compared to south-facing (based on PVGIS data for central England), but the split generation curve puts power into your home when you actually need it: mornings and evenings.
Home solar energy systems can be a worthwhile investment, but they are not all made equal. Factors like panel orientation and the angle at which they meet the sun make a real difference. In this series I will explore the advantages and disadvantages of each roof direction and help you select the right system for an East/West roof.
An east/west split is often dismissed as second-best, but its generation curve matches typical household demand better than a south-facing roof ever could.
What This Roof Must Optimise For
- Self-consumption over export. The E/W generation curve naturally aligns with morning and evening demand peaks. Every kWh you use directly saves 27.69p. Every kWh you export earns 5p. Size the system to consume as much as possible.
- Dual-MPPT inverter, non-negotiable. East and west panels generate at different times of day. You need one MPPT tracker per roof face so the inverter can independently optimise each string. A single-MPPT inverter would force both strings to the same voltage, losing 10-15% of potential output.
- Overpanel both faces. With E/W orientation producing ~81% of south-facing yield per panel (PVGIS), you need more panels to hit the same total output. Target 130-150% of the inverter AC rating. In UK conditions with E/W, clipping is minimal.
Opportunities
East/west panels produce 81% of a south-facing roof per kWp (PVGIS data, 28° tilt, central England). In practice, the UK’s heavily overcast skies narrow this gap because diffuse light, which makes up roughly 55-60% of annual irradiance in England (based on PVGIS-SARAH3 data), arrives from all directions rather than concentrated from the south.
The real advantage is the generation shape. South-facing panels create a sharp midday spike that mostly gets exported at 5p/kWh. East/west panels spread generation across a wider window. East panels catch the 7-10am slot when the kettle, toaster, and washing machine run. West panels produce through the 4-7pm cooking and entertainment window. For a typical family that is out during the day, this is a better fit than south.
Your 3-Bed Consumption Profile
Low to Mid Consumption: 2,900 kWh/year
A 3-bedroom household on gas central heating with standard appliances uses around 2,900 kWh of electricity per year, based on Ofgem Typical Domestic Consumption Values. That is roughly £803 at the current price cap rate of 27.69p/kWh. Your base loads are lighting, fridge/freezer, cooking, washing, and entertainment. Most demand concentrates in the morning (7-9am) and evening (5-9pm), with a dip during the day unless someone works from home.
At this consumption level, an east/west roof is actually well matched. The morning and evening generation peaks overlap with your demand peaks. A modest battery captures the midday surplus and releases it in the evening gap between west-face sunset and bedtime loads.
High Consumption: 6,500+ kWh/year
If you run a heat pump, charge an EV at home, or both, your annual consumption jumps to 6,500 kWh or more. A heat pump adds 3,000-5,000 kWh/year depending on your home’s insulation. An EV adds 2,000-3,500 kWh depending on mileage. Your annual bill could hit £1800+.
At this consumption level, your daytime base load is substantial. The heat pump cycles throughout the day, the hot water tank heats, and these loads overlap with whatever generation your east/west panels produce. This is actually good news for solar because you will self-consume a much higher proportion of what you generate.
High consumption homes benefit the most from E/W. The spread generation feeds a heat pump that runs in the morning and afternoon, and an EV that can be scheduled to charge during solar hours. With a battery, the budget system hits 97% self-consumption at this tier.
Budget Option
Solar Energy Concepts System Rating
System Specification
Inverter: Solis 3.6kW 5G Hybrid EH1 (£575-653)
- AC output: 3.6kW (G98 compliant, notification only)
- 2 independent MPPTs, 1 string each
- Max DC input: 600V / 15A per MPPT / 5.7kW total
- MPPT range: 90-520V
- Hybrid design allows battery addition later without replacing the inverter
Overpanelling target: 148% of the 3.6kW AC rating = 5,340W DC. With E/W panels producing ~81% of south-facing yield, overpanelling is how you close the gap. In UK conditions with an east/west split, you will rarely clip because the two faces never peak simultaneously. The east string peaks at 10am while the west string is still warming up, and vice versa in the afternoon.
The DMEGC 450W is the cheapest panel in the UK at £61/panel, but its short-circuit current (Isc) of 15.4A exceeds the Solis EH1’s 15A per-MPPT limit. That rules it out for this inverter.
Panel Options
| Strategy | Panels | Total DC | Overpanel % | String Check |
|---|---|---|---|---|
| Best value | JA Solar 445W × 12 (6 East + 6 West) | 5,340W | 148% | Voc: 6 × 39.1V = 234.6V < 600V. Vmp: 6 × 32.65V = 195.9V in 90-520V. Isc 14.43A < 15A. OK. |
| Smallest footprint | Aiko Neostar 490W × 10 (5 East + 5 West) | 4,900W | 136% | Voc: 5 × 40.98V = 204.9V < 600V. Vmp: 5 × 34.4V = 172V in 90-520V. Isc 14.93A < 15A. OK. |
| Max overpanel | LONGi Hi-MO X6 455W × 12 (6 East + 6 West) | 5,460W | 152% | Voc: 6 × 39.15V = 234.9V < 600V. Vmp: 6 × 32.98V = 197.9V in 90-520V. Isc 14.79A < 15A. OK. |
The JA Solar 445W at £64/panel is the cheapest compatible panel per watt (14.4p/W). The Aiko Neostar 490W has the highest efficiency at 24.5%, fitting 4,900W into just 10 panels (pricing not confirmed from UK distributors at time of writing). The LONGi Hi-MO X6 455W at £73/panel gives 120W more total DC than the JA Solar option at the same panel count.
Battery
Fogstar 5.12kWh Server Rack (£730-900)
The budget battery target for a 3-bed home is ~5.3 kWh (two-thirds of the 7.9 kWh daily average consumption). The Fogstar 5.12kWh at £730 is the most cost-effective option in the UK market right now. It is a 48V LFP rack unit that connects directly to the Solis EH1 hybrid inverter. On an E/W roof, the battery captures the lunchtime generation that falls between the morning and evening demand peaks, then releases it after sunset.
Total system cost:
- DIY: £2,250-2,550
- Installed: £5,000-5,700
DIY Feasibility
A dual-MPPT system is only slightly more complex than a single-string setup. You run two separate DC cables from the roof (one per face) into the inverter. The Solis EH1 has clearly labelled MPPT1 and MPPT2 inputs. The battery connects via a separate DC port. The main consideration is running cables from both sides of the roof through the loft space to the inverter location.
You can mount the panels, run the DC cabling, and install the inverter yourself. You will need a qualified electrician to make the final AC connection to your consumer unit (Part P of building regulations). Budget £150-300 for this. No MCS certification is needed for the install itself, though you will not be eligible for SEG export payments without MCS. For a system sized for self-consumption, losing SEG income is negligible.
Expected Performance
| Metric | Low-Mid (2,900 kWh) | High (6,500 kWh) |
|---|---|---|
| Annual yield | 4,084 kWh | |
| Self-consumption (with 5.12 kWh battery) | 60% (2,435 kWh) | 97% (3,966 kWh) |
| Export | 40% (1,629 kWh) | 2% (98 kWh) |
| Grid savings | £674/year | £1098/year |
| Export income (SEG 5p) | £81/year | £5/year |
| Total annual saving | £756/year | £1103/year |
Premium Option
Solar Energy Concepts System Rating
System Specification
Inverter: Solis 5.0kW S5 Smart Hybrid (£707-770)
- AC output: 5.0kW (requires G99 application, not just notification)
- 2 independent MPPTs, 1 string each
- Max DC input: 600V / 15A per MPPT / 8.0kW total
- MPPT range: 90-520V
- Hybrid design with native battery port
Overpanelling target: 142% of the 5.0kW AC rating = 7,120W DC. The Solis S5 has 8.0kW max DC input, so 7.12kW sits comfortably within limits. With 8 panels per face, each MPPT handles its own string independently.
Panel Options
| Strategy | Panels | Total DC | Overpanel % | String Check |
|---|---|---|---|---|
| Best value | JA Solar 445W × 16 (8 East + 8 West) | 7,120W | 142% | Voc: 8 × 39.1V = 312.8V < 600V. Vmp: 8 × 32.65V = 261.2V in 90-520V. Isc 14.43A < 15A. OK. |
| Smallest footprint | Aiko Neostar 490W × 14 (7 East + 7 West) | 6,860W | 137% | Voc: 7 × 40.98V = 286.9V < 600V. Vmp: 7 × 34.4V = 240.8V in 90-520V. Isc 14.93A < 15A. OK. |
| Max overpanel | LONGi Hi-MO X6 455W × 16 (8 East + 8 West) | 7,280W | 146% | Voc: 8 × 39.15V = 313.2V < 600V. Vmp: 8 × 32.98V = 263.8V in 90-520V. Isc 14.79A < 15A. OK. |
Battery
Fogstar 16.1kWh ECO (£1,850)
The premium battery target for a 3-bed home is 11.9 kWh or more (150% of the 7.9 kWh daily average). The Fogstar 16.1kWh exceeds this target and provides genuine multi-day resilience. On winter evenings when E/W panels produce very little, the battery bridges the gap. In summer, it captures the midday surplus from both faces and powers the home until midnight.
The 16.1kWh capacity also enables winter tariff arbitrage. Charge overnight on Octopus Go at 7.5p/kWh, discharge during the day at 27.69p. That 20p/kWh spread across 16kWh is £3.20 per day, or roughly £96/month in the darkest months.
Total system cost:
- DIY: £3,900-4,300
- MCS installed: £9,300-10,200
G99 and MCS
At 5.0kW AC output, this system exceeds the G98 threshold of 3.68kW. You must apply for G99 permission from your DNO before connecting. This is a formal application, not a notification. Most DNOs approve residential G99 within 45 days, but some regions (notably SSEN in Scotland and parts of Southern England) can take longer if the local grid is constrained.
MCS certification is recommended for the premium option because: (a) you qualify for SEG export payments, which become meaningful at this generation level, (b) the battery enables time-of-use tariff strategies that require a certified installation for some suppliers, and (c) it protects your home insurance and property value.
When This Makes Sense vs Overkill
Worth it if: You have a heat pump or EV, or plan to add one within 2-3 years. At high consumption, the premium system self-consumes 84% of its output. The 16.1kWh battery handles winter evenings and enables Octopus Go arbitrage when solar output drops. E/W systems export less than south-facing systems of the same size, so the extra panels earn their keep.
Overkill if: You are a low-consumption household with no plans to electrify heating or transport. The budget system already delivers a solid return. The extra cost for the premium setup extends payback to 4.7 years (DIY), and the larger battery puts more capital at risk from future price changes.
Expected Performance
| Metric | Low-Mid (2,900 kWh) | High (6,500 kWh) |
|---|---|---|
| Annual yield | 5,445 kWh | |
| Self-consumption (with 16.1 kWh battery) | 48% (2,615 kWh) | 84% (4,581 kWh) |
| Export | 51% (2,803 kWh) | 15% (837 kWh) |
| Grid savings | £724/year | £1268/year |
| Export income (SEG 5p) | £140/year | £42/year |
| Total annual saving | £864/year | £1310/year |
Tariff Strategy and DNO Notes
Budget option: A flat-rate tariff works fine. Your savings come from self-consumption. The 5.12kWh battery shifts midday surplus to the evening, which is where most of your value comes from. If electricity prices rise (they tend to), your returns improve automatically.
Premium option: Octopus Go is the natural fit. Charge your battery overnight at 7.5p/kWh and discharge during the evening peak at 27.69p. In summer, solar handles the charging. In winter, cheap off-peak grid power fills the battery instead. The E/W generation curve means you export less during peak solar hours, making SEG income a smaller part of the equation than it would be for a south-facing system.
DNO Region Considerations
E/W systems export less aggressively than south-facing setups because generation is spread across the day rather than concentrated at midday. This makes DNO approval straightforward even in constrained areas.
G98 (budget, 3.6kW): Notification-only. All DNOs process this within days. No practical regional variation.
G99 (premium, 5.0kW): Application required. Turnaround varies by DNO:
- UKPN (London, South East, East): Generally fast, 20-30 working days
- WPD / National Grid ED (Midlands, South West, Wales): Moderate, 30-45 days
- NPG (North East, Yorkshire): Generally fast, 20-30 days
- SSEN (Scotland, parts of South): Can be slow, 45-60+ days. Known for grid constraint issues in rural areas
- ENW (North West): Moderate, 30-45 days
If you are in an SSEN area and planning a 5kW system, submit your G99 application early. Do not wait until the panels arrive.
ROI Comparison
| Budget DIY | Budget Installed | Premium DIY | Premium MCS | |
|---|---|---|---|---|
| Low-Mid Consumption (2,900 kWh/year) | ||||
| Upfront cost | £2,400 | £5,350 | £4,100 | £9,750 |
| Annual saving | £756 | £756 | £864 | £864 |
| Payback | 3.2 years | 7.1 years | 4.7 years | 11.3 years |
| 25-year return | £18,900 | £18,900 | £21,600 | £21,600 |
| High Consumption (6,500 kWh/year) | ||||
| Upfront cost | £2,400 | £5,350 | £4,100 | £9,750 |
| Annual saving | £1103 | £1103 | £1310 | £1310 |
| Payback | 2.2 years | 4.9 years | 3.1 years | 7.4 years |
| 25-year return | £27,575 | £27,575 | £32,750 | £32,750 |
Assumes flat electricity rate of 27.69p/kWh, SEG at 5p/kWh, no energy inflation, and 0.5% annual panel degradation. Real returns are likely higher as energy prices tend to rise over 25 years.
Generation Yield Source
All yield estimates in this guide are derived from PVGIS (Photovoltaic Geographical Information System), the European Commission’s free solar radiation database. PVGIS uses satellite-measured irradiance data and is the standard reference for solar yield calculations across Europe.
Simulation Parameters
| Parameter | Value |
|---|---|
| Location | 52.308°N, -0.717°W (Central England reference) |
| Roof slope | 28° |
| System loss | 14% |
| Database | PVGIS-SARAH3 |
Yield by Roof Face
| System | Face | PVGIS Aspect | E_y (kWh/kWp/yr) | DC Capacity | Annual Yield |
|---|---|---|---|---|---|
| Budget | East | -90° | 804.98 kWh/kWp | 2.67 kWp | 2,149 kWh |
| Budget | West | +90° | 788.18 kWh/kWp | 2.67 kWp | 2,104 kWh |
| Premium | East | -90° | 804.98 kWh/kWp | 3.56 kWp | 2,866 kWh |
| Premium | West | +90° | 788.18 kWh/kWp | 3.56 kWp | 2,806 kWh |
Clipping factor applied: 0.96 (accounts for inverter limiting when DC input exceeds AC capacity).
Budget total annual yield after clipping: 4,084 kWh
Premium total annual yield after clipping: 5,445 kWh
You can verify these figures yourself using the PVGIS interactive tool. Enter your postcode for location-specific results:
