Plug-in solar (balcony solar) is “worth it” under specific conditions, but it is not a real alternative as you may think.
In the UK there was a scam with solar called rent a roof as was the main drive behind older solar systems installed from around 2000. Plug in solar, it pretty much a similar scam on a different scale, and here is why.
Value Proposition
- The Goal: Offsetting daytime “baseload” consumption (refrigerators, Wi-Fi routers, idle electronics, standby devices).
- Typical Setup: 1–2 panels (approx. 400W–800W) connected via a micro inverter directly into a standard wall socket.
- Upfront Cost: £400–£1,000 / $500–$1,200 depending on region, panel count, and mounting hardware.
- Estimated ROI: Payback typically ranges between 3 to 6 years** depending on local electricity tariffs and direct sunlight exposure.
When It Makes Sense
- You rent or live in a property where permanent roof mounting is prohibited or structurally impractical.
- You have a clear, unshaded south- or south west-facing balcony, terrace, or ground space.
- Your household maintains a continuous daytime baseline draw (working from home, running background appliances)*.
When to Avoid It
- High Instantaneous Loads: It will not run high-draw appliances like heat pumps, EV chargers, or electric showers independently.
- Shaded Positioning: North-facing or heavily shaded placement negates financial return due to micro inverter minimum operational thresholds.
- Regulatory Restrictions: Regional grid codes vary. In some jurisdictions, anti-islanding compliance, micro inverter approvals, or utility notification are strictly required before back feeding into a final ring circuit.
** RenewSolar ROI is less than 2 years
* this is the real issue.
Why is plug in solar a scam
When you are more behind the scenes of energy and government or the big company; power and people are not a balanced relationship, the company want to make money from you and the government is the tool they use. There is a bigger “economics” reason. but it really makes sense when you look at how the solar actually works.
image showing solar production in the real world – System design Renewsolar,
Power used at home, “the base load” is usually low, around 100W for many homes and around 200W, day time base loads can be around 450W. If I use percentages then it makes sense.
to understand how solar works, we have to use percentages and time, as the two go hand in hand with solar
On a midsummer day in the UK Midlands (latitude ~52.5°N), the sun reaches a high solar elevation angle of roughly 61° above the horizon at solar noon (~1:00 PM BST).
When solar panels are installed vertically (90° tilt) facing due South, this steep sun angle creates a distinctive bimodal (“camel-hump”) power curve:
- Mid-morning Peak (~10:00–10:30 AM BST): As the sun enters the southern sky at a moderate elevation angle (~35°–40°), sunlight strikes the vertical panel face at an optimal angle of incidence.
- Midday Saddle / Dip (~12:30–1:30 PM BST): At solar noon, when overall solar radiation is at its peak, the sun sits directly above the panel. Because light glances off the vertical surface at a steep top-down angle (approx 61 off perpendicular), direct power output dips significantly compared to a tilted roof.
- Mid-afternoon Peak (~3:30–4:00 PM BST): As the sun descends lower into the southwestern sky, the angle of incidence improves again, generating a second peak before falling off toward sunset.
Daily Profile Summary (Standard 800W Plug-In Kit)
| Parameter | Standard 35° South Roof | Vertical 90° South Wall / Balcony |
| Peak Power Time | 1:00 PM BST (Single Sharp Peak) | 10:15 AM & 3:45 PM BST (Twin Peaks) |
| Max Peak Output | ~650W – 720W | ~420W – 480W |
| Midday Output (1 PM) | ~700W | ~350W – 380W (Midday Glance Dip) |
| Total Daily Summer Yield | ~4.8 – 5.5 kWh | ~3.1 – 3.6 kWh (~35% lower overall) |
| Self-Consumption Fit | High midday export potential | Excellent alignment with morning/afternoon home baseload |
What that looks like…
So looking at this power curve you are looking at producing power, so would tilt your panels, makes sense?
What we want to do is look at two homes and what power they use over the day with a 800w system installed.
Here is the 24-hour power curve comparing an 800W plug-in solar setup (35° South tilt) against the consumption profiles of both Persona 1 (Single Working Person) and Persona 2 (Family of 4) on a UK summer day.
Quantitative Breakdown & Solar Alignment
| Metric | 800W Plug-In Solar (35° Tilt) | Persona 1: Single Working Person | Persona 2: Family of 4 |
| Total Daily Energy | 7.13 kWh generated | 5.51 kWh consumed | 16.21 kWh consumed |
| Daytime Baseload | N/A | 100 W (08:00–18:00) | 150 W (24/7 continuous) |
| Peak Power Spikes | ~0.70 kW (at 13:00) | 8.10 kW (Shower + Baseload) | 8.15 kW (Shower / Cooking) |
| Direct Solar Used | N/A | 1.77 kWh | 3.98 kWh |
| Solar Self-Consumption % | N/A | 24.9% (75.1% exported/lost) | 55.8% (44.2% exported) |
| Electricity Bill Offset % | N/A | 32.2% of daily bill | 24.5% of daily bill |
As you can see the use of power and the production in what would be IDEAL conditions ( clear skies in the summer). You are exporting almost twice the amount you would use. At RenewSolar we save “you only save what you use” and this is typical of grid tied solar. – Grid tied is a solar installation that works with the grid, has no battery and exports excess power.
You do not get paid for the export, however the energy company does.
Making solar work for you –
The old RenewSolar slogan
By adding battery storage to an 800W plug-in solar system alters energy self-consumption, but performance is governed by two physical constraints:
- The 800W Output Cap: Plug-in micro inverters/batteries export a maximum of 800W back into the wall socket. Spikes like an 8kW electric shower or 2.5kW cooker still pull the majority of their power from the grid.
- Total Solar Generation Limit: An 800W array on a UK summer day yields ~7.13 kWh total. If daytime consumption is high, there is insufficient excess solar to fill a large battery.
Comparative Battery Performance (800W Solar Kit)
| Metric | Baseline (No Battery) | + 2 kWh Battery | + 5 kWh Battery |
| Persona 1: Single Working Person | |||
| Total Daily Demand | 5.51 kWh | 5.51 kWh | 5.51 kWh |
| Solar Utilised (Direct + Battery) | 1.77 kWh | 3.76 kWh | 4.97 kWh |
| Solar Self-Consumption % | 24.9% | 52.7% | 69.8% |
| Remaining Daily Grid Import | 3.74 kWh | 3.71 kWh | 3.69 kWh |
| Battery Utilisation | N/A | 100% full daily | ~70% filled |
| Persona 2: Family of 4 | |||
| Total Daily Demand | 16.21 kWh | 16.21 kWh | 16.21 kWh |
| Solar Utilised (Direct + Battery) | 3.98 kWh | 6.55 kWh | 6.65 kWh |
| Solar Self-Consumption % | 55.8% | 91.8% | 93.2% |
| Remaining Daily Grid Import | 12.23 kWh | 12.19 kWh | 12.19 kWh |
| Battery Utilisation | N/A | 100% full daily | <60% filled (severely underutilised) |
Operational Analysis
1. Persona 1 (Empty House During Day)
- 2 kWh Battery: Captures evening TV and baseload needs. Increases solar usage from 1.77 kWh to 3.76 kWh.
- 5 kWh Battery: Captures almost all daytime excess solar (~5.36 kWh available excess). Increases solar utilisation to 4.97 kWh.
- Grid Import Limit: Grid import drops to ~3.7 kWh but cannot go lower because the 10-minute 8kW shower consumes ~1.33 kWh in a burst that exceeds the battery’s 800W discharge rate.
2. Persona 2 (High Daytime Demand)
- 2 kWh Battery: Reaches 91.8% solar self-consumption. The battery absorbs the ~2.8 kWh of daytime excess and discharges it during evening gaming, TV, and dishwasher cycles.
- 5 kWh Battery: Diminishing returns. Because daytime activities already consume 3.98 kWh of solar directly, only ~3.15 kWh of excess solar generation remains across the entire day. The 5 kWh battery only yields an additional 0.10 kWh/day over the 2 kWh model because there is not enough surplus solar to charge it.
Sizing Recommendation
- 2 kWh Battery: The optimal economic balance for plug-in solar. It captures over 90% of available excess power for occupied homes and doubles self-consumption for unoccupied homes.
- 5 kWh Battery: Oversized for a standard 800W plug-in solar array unless charged overnight on an off-peak grid tariff (e.g., Octopus Go / Economy 7). Without off-peak grid charging, an 800W panel setup cannot generate enough surplus to justify 5 kWh of storage capacity.
Important considerations
DONT RUSH – important factors have to be considered before you jump on the data sets that we have wrote about. the real world works differently and we do not live in the summer with clear sky’s every day.
Sizing Conclusions at 5.2 kWh/day
- Persona 1 (Empty House):
- Total unconsumed daytime surplus drops from ~5.36 kWh to 3.55 kWh.
- A 2 kWh battery captures 1.91 kWh of surplus, pushing self-consumption to 68.4%.
- A 5 kWh battery captures 3.00 kWh of surplus (reaching 89.5% self-consumption), but never fully charges because total daily surplus tops out at 3.55 kWh.
- Persona 2 (Occupied House):
- High daytime usage directly absorbs 3.45 kWh, leaving only 1.75 kWh of total surplus across the entire day.
- A 2 kWh battery captures almost 100% of available excess power (1.48 kWh usable output after conversion losses), raising self-consumption to 94.8%.
- A 5 kWh battery provides zero additional value over a 2 kWh battery, remaining more than 60% empty every single day unless charged directly from an off-peak grid tariff overnight.
Add another plug in solar 800w into the data set.
Adding a second 800W plug-in unit (doubling total capacity to 1600W and daily yield to 10.4 kWh) shifts the primary system constraint from generation scarcity to storage capacity and local grid regulations.
Comparative Analysis (1600W / 10.4 kWh Daily Output)
| Metric | Baseline (No Battery) | + 2 kWh Battery | + 5 kWh Battery |
| Persona 1: Single Working Person | |||
| Direct Solar Used | 1.94 kWh | 1.94 kWh | 1.94 kWh |
| Battery Discharge Used | 0.00 kWh | 2.05 kWh | 3.05 kWh |
| Total Solar Utilised | 1.94 kWh (18.6%) | 3.99 kWh (38.3%) | 4.99 kWh (47.9%) |
| Exported / Unused Surplus | 8.46 kWh | 6.41 kWh | 5.41 kWh |
| Persona 2: Family of 4 | |||
| Direct Solar Used | 4.55 kWh | 4.55 kWh | 4.55 kWh |
| Battery Discharge Used | 0.00 kWh | 2.97 kWh | 4.95 kWh |
| Total Solar Utilised | 4.55 kWh (43.7%) | 7.52 kWh (72.3%) | 9.50 kWh (91.4%) |
| Exported / Unused Surplus | 5.85 kWh | 2.88 kWh | 0.90 kWh |
Key System Dynamics & Trade-offs
1. Reversal of the 5 kWh Battery Dynamics
- With 800W (5.2 kWh yield): The 5 kWh battery was oversized because there was not enough excess solar to charge it.
- With 1600W (10.4 kWh yield): The 5 kWh battery becomes highly effective for Persona 2, increasing self-consumption from 72.3% to 91.4% and covering almost all evening baseload, TV, and gaming draw.
2. Diminishing Returns for Unoccupied Homes (Persona 1)
- Without a battery, Persona 1 exports 81.4% (8.46 kWh) of generated solar directly to the grid uncompensated.
- Even with a 5 kWh battery, Persona 1 caps out at 4.99 kWh of total daily solar use due to low total evening demand.
The importance of value
Based on an electricity tariff of £0.30 / kWh and an average UK annual solar yield (~720 kWh/year per 800W array), here is the financial return on investment (ROI) and simple payback period analysis across the hardware configurations.
Hardware Cost Breakdown
- 800W Solar Kit Only: £375
- 800W Solar Kit + 5kWh Battery: £1,125 (£375 + £750)
- 1600W Solar Kit (2x 800W) + 5kWh Battery: £1,500 (£750 + £750)
Financial ROI & Payback Comparison Table
| System Configuration | Total Upfront Cost | Persona 1 (Single Working Person)Empty Daytime | Persona 2 (Family of 4)High Daytime & Evening Load |
| 800W Solar Only | £375 | • Saved: £75.60/yr (252 kWh) • Payback: 5.0 years • Annual ROI: 20.2% | • Saved: £140.40/yr (468 kWh) • Payback: 2.7 years • Annual ROI: 37.4% |
| 800W Solar + 5kWh Battery | £1,125 | • Saved: £172.80/yr (576 kWh) • Payback: 6.5 years • Annual ROI: 15.4% | • Saved: £198.60/yr (662 kWh) • Payback: 5.7 years • Annual ROI: 17.7% |
| 1600W Solar + 5kWh Battery | £1,500 | • Saved: £255.00/yr (£850 kWh) • Payback: 5.9 years • Annual ROI: 17.0% | • Saved: £375.00/yr (1,250 kWh) • Payback: 4.0 years • Annual ROI: 25.0% |
Key Financial Takeaways
- Fastest Payback (800W Solar Only):For an occupied home (Persona 2), the stand-alone £375 solar kit pays for itself in just 2.7 years because daytime appliances directly consume the solar output without requiring battery storage.
- The 800W + 5kWh Disconnect:Pairing an 800W solar array with a 5kWh battery extends the payback period to 5.7–6.5 years. The 800W array does not generate enough surplus power during spring/autumn to fully cycle a 5kWh battery daily.
- Sweet Spot for the 5kWh Battery (1600W Array):If investing £750 in a 5kWh battery, pairing it with a 1600W solar setup (£1,500 total) yields significantly better financial performance for a family, reducing payback down to 4.0 years (£375 annual savings).
- Off-Peak Tariff Arbitrage Option:The payback of the 5kWh battery can be accelerated further if charged from the grid overnight during winter on a cheap off-peak tariff (e.g., £0.07–£0.09/kWh) and discharged during peak daytime rates (£0.30/kWh).
There are more ways to make this a better deal. Without adding an additional inverter, you can add solar and a CC, this can directly charge the battery from solar, but it is not a year round good option for the costs.
There is also a real importance to “not keep flogging a dead horse”.
while this may seem like a money extraction, it is all based on value to you. The entry point is bad value to you.
If you are going to pick a double plug in 800w system, then you are better off buying a larger micro inverter and having it installed professionally. The 2kw micro inverter supports 4 solar panels. while giving you a higher output and base load coverage. The cost difference is around £35, installation can be as little as £150.
Upgrading out of the plug in limits
Upgrading to a 2kW micro inverter system (paired with a ~2kW solar array yielding ~13.0 kWh on a summer day) and a 5kWh battery removes the 800W output bottleneck.
What Changes with a 2kW Inverter Capacity?
- Appliance Coverage: Instead of capping output at 800W, the inverter now delivers up to 2,000W continuously.
- High-Draw Appliances Covered: Kettles (2kW), washing machines (1.8kW–2kW), dishwashers (1.8kW), and fryers (2kW) are now 100% powered by solar/battery without pulling from the grid.
- Partial Shower Offsetting: An 8kW electric shower still exceeds inverter capacity, but the 2kW inverter offsets 25% of its power draw (drawing 2,000W from solar/battery and 6,000W from the grid).
Daily Performance Comparison (2kW Inverter + 2kW Solar + 5kWh Battery)
| Performance Metric | Persona 1: Single Working Person(5.51 kWh Total Daily Load) | Persona 2: Family of 4(16.21 kWh Total Daily Load) |
| Summer Daily Solar Yield | 13.00 kWh | 13.00 kWh |
| Direct Daytime Solar Used | 1.95 kWh | 5.80 kWh |
| 5kWh Battery Discharged | 2.80 kWh (Fully covers evening) | 5.00 kWh (100% discharged by 22:30) |
| Total Solar Energy Utilized | 4.75 kWh / day | 10.80 kWh / day |
| Solar Self-Consumption % | 36.5% (8.25 kWh surplus exported) | 83.1% (2.20 kWh surplus exported) |
| Electricity Bill Reduction % | 86.2% offset (Grid import: ~0.76 kWh) | 66.6% offset (Grid import: ~5.41 kWh) |
24-Hour Power Curve & Demand Chart
Above: Single person user, has battery reserve.
Below: Family average, full cycle battery.
Financial ROI & Payback Matrix (at £0.30 / kWh)
| Metric | Scenario A: Total Cost = £1,650 | Scenario B: Total Cost = £1,950 |
| Persona 1: Single Working Person | ||
| Annual Energy Saved | 1,150 kWh | 1,150 kWh |
| Annual Financial Savings | £345.00 / year | £345.00 / year |
| Simple Payback Period | 4.8 years | 5.7 years |
| Annual ROI | 20.9% | 17.7% |
| Persona 2: Family of 4 | ||
| Annual Energy Saved | 1,650 kWh | 1,650 kWh |
| Annual Financial Savings | £495.00 / year | £495.00 / year |
| Simple Payback Period | 3.3 years | 3.9 years |
| Annual ROI | 30.0% | 25.4% |
Core Financial Takeaway
- At £1,650, payback remains 3.3 years for Persona 2 and 4.8 years for Persona 1.
- Even if higher panel pricing pushes total system investment to £1,950, the payback period for a family remains under 4 years, yielding an annual return of 25.4%—outperforming standard cash savings and index yields.
I hope this has given you a sight into making solar work for you and how you select a system can offer value or not, for the most part a simple plug in system will not offer use great savings and put a dent in your power bill.
For others who are more concerned about lining the pockets of others, and the scam we mentioned, here is Their profits from your solar installation per year. The power company does not want to put money into what was a public company, they have skimmed the profits and lacked any reasonable investment into the infrastructure.
The idea ( as per there disclosure documents) was to transfer this to the paying public.
The two objectives were:
People buy solar, reducing power production costs,
people install batteries to store solar but saves the grid buying batteries.
– G100 and DRM control, allows the grid to control your battery and production as if it was theirs to use. We see this coming into effect, and the low payment for power export by many companies.
Of course this is generally marketed differently than plain honesty of the objectives.. It would be damaging to the companies putting there prices up and making multi billion pounds a year in profits to dump its network costs on people and still make a standing charge for this. Some may say immoral. but when adding the taxpayer grants and funds and compensation is just outrageous.
Below: charting grid annual profiting as per the system installed.
YOUR SAVINGS: zero export value. how many solar work for you (not them).
In this scenario ( normalised), any solar generation exceeding immediate household demand or battery storage capacity is curtailed (dumped to the grid for £0.00). Only energy directly displacing imported grid power delivers financial value.
Monthly Yield vs. Realised Bill Savings (£0.30 / kWh)
A 1600W south-facing array in the UK yields ~1,496 kWh annually. Adding a 5kWh battery enables both personas to capture almost all shoulder and winter generation, though Persona 1 experiences summer curtailment due to lower overall load.
| Month | Expected 1600W Yield (kWh) | Persona 1 (Single Working) Self-Consumed kWh (Bill £ Saved) | Persona 2 (Family of 4) Self-Consumed kWh (Bill £ Saved) | Solar Energy Wasted / Uncompensated |
| Jan | 44.8 kWh | 41.2 kWh (£12.36) | 42.1 kWh (£12.63) | 0% |
| Feb | 72.0 kWh | 66.2 kWh (£19.86) | 67.7 kWh (£20.31) | 0% |
| Mar | 120.0 kWh | 110.4 kWh (£33.12) | 112.8 kWh (£33.84) | 0% |
| Apr | 168.0 kWh | 150.0 kWh (£45.00) | 157.9 kWh (£47.37) | ~5–10% (P1) |
| May | 200.0 kWh | 155.0 kWh (£46.50) | 188.0 kWh (£56.40) | ~22% (P1) / 6% (P2) |
| Jun | 208.0 kWh | 150.0 kWh (£45.00) | 195.5 kWh (£58.65) | ~28% (P1) / 6% (P2) |
| Jul | 200.0 kWh | 155.0 kWh (£46.50) | 188.0 kWh (£56.40) | ~22% (P1) / 6% (P2) |
| Aug | 176.0 kWh | 155.0 kWh (£46.50) | 165.4 kWh (£49.62) | ~12% (P1) |
| Sep | 136.0 kWh | 125.1 kWh (£37.53) | 127.8 kWh (£38.34) | 0% |
| Oct | 88.0 kWh | 81.0 kWh (£24.30) | 82.7 kWh (£24.81) | 0% |
| Nov | 48.0 kWh | 44.2 kWh (£13.26) | 45.1 kWh (£13.53) | 0% |
| Dec | 35.2 kWh | 32.4 kWh (£9.72) | 33.1 kWh (£9.93) | 0% |
| TOTAL | 1,496.0 kWh | 1,265.5 kWh (£379.64**)** | 1,406.2 kWh (£421.87**)** |
Seasonal Breakdown
- Winter Base (Nov – Feb): ~200 kWh Total (~1.6 kWh/day)
- Behaviour: Generation rarely fills the 5kWh battery.
- Bill Impact: 100% of generated solar power is consumed immediately or used in the evening. No solar energy is wasted.
- Shoulder Transitions (Mar, Apr, Sep, Oct): ~512 kWh Total (~4.2 kWh/day)
- Behaviour: Daily output aligns with the 5kWh battery capacity.
- Bill Impact: Persona 1 and Persona 2 utilise 90%–98% of all generated solar power.
- Summer Peak (May – Aug): ~784 kWh Total (~6.4 kWh/day)
- Behaviour: On sunny summer days, generation hits 8.0–9.5 kWh/day.
- Persona 1 Constraint: Because total daily load is ~5.51 kWh, the 5kWh battery tops off by 14:00. The remaining 2.0–3.5 kWh/day of excess generation is dumped to the grid uncompensated.
- Persona 2 Advantage: Higher background load and frequent appliance cycles allow Persona 2 to absorb almost all peak solar generation, wasting under 6%.
- Behaviour: On sunny summer days, generation hits 8.0–9.5 kWh/day.
Financial Payback (Zero Export Payment)
Assuming a total hardware setup cost of £1,350 (£600 1600W panels + £750 5kWh battery):
- Persona 1 (Single Working Person):
- Realised Annual Bill Savings: £379.64 (84.6% solar utilisation)
- Simple Payback Period: 3.55 years
- Annual ROI: 28.1%
- Persona 2 (Family of 4):
- Realised Annual Bill Savings: £421.87 (94.0% solar utilisation)
- Simple Payback Period: 3.20 years
- Annual ROI: 31.2%
RenewSolar is a global leader in solar and renewable energy; with over 20 years experience in a global market of over 40 years, the skill sets set RenewSolar above all others and why many turn to us for for their solar consultations and installations. RenewSolar offers consultations and installations, along with project management.
Clients benefit from savings of up to 70% making RenewSolar both cost effective and the top choice.
No responses yet