Alectrona
Commercial solar by system sizeThe 500 to 750 kWp band is large-roof commercial solar, where the array fills a distribution shed or a cold store and the design is shaped by insurer-driven rapid shutdown and the limits of your grid connection.
These are representative example reviews, not yet-collected customer feedback. They are written to illustrate the kind of feedback Alectrona aims to earn and are shown as design placeholders while we gather and verify reviews from our first commercial clients. Alectrona is the commercial solar trading brand of RVTC LTD.
What set Alectrona apart was the documented design pack. We had quotes from three installers, but only Alectrona handed us a full set of drawings, a single-line diagram and a design referencing BS 7671 and the G99 connection process. The whole thing read like an engineering submission rather than a sales brochure. Our M&E consultant reviewed it and signed it off without a single query. That gave the board the confidence to release the capital.
Other firms priced our roof off a satellite image and a desktop guess. Alectrona flew an in-house drone survey, fully insured and flown by a qualified commercial drone pilot, and built a 3D model of the actual roof. It picked up plant, vents and a parapet line that a flat aerial photo had completely missed, which changed the panel layout. I would rather find that out at design stage than on the day the scaffold goes up. The accuracy of that survey is the reason I trusted everything that followed.
As a finance director I was wary of being oversold a system bigger than we could use. Alectrona modelled the array against our actual half-hourly consumption data rather than an annual total, so it is sized to what we genuinely draw on site during the day. They were honest that exporting surplus is worth far less than self-consumption, and built the design around that. The capital case stacked up because the engineering was honest, not because the numbers were inflated.
We were undecided between buying outright, leasing and a PPA. Alectrona laid out all three side by side with the pros and cons of each against our balance sheet, instead of pushing the one that pays them best. They were clear about where a PPA makes sense and where capex wins, and pointed us at our own accountant for the tax treatment. The survey and design took a little longer than I expected, but the thoroughness was worth the wait. Genuinely consultative.
The install crew were tidy and well run, and worked to a clear CDM 2015 plan with a proper site induction and RAMS. What impressed me most was the handover. We received a full commissioning pack with the IEC 62446-1 test results, certification, O&M documentation and an as-built record for our maintenance team. As the people who have to live with this asset for the next twenty years, having that paperwork in order matters enormously. Nothing was left loose.
I expected the usual hard sell and got the opposite. After surveying our site Alectrona told us one roof section was not worth covering because of shading, and that a smaller, well-sited array was the better investment than filling every square metre. There was no commission-driven upselling and no pressure. For a six-figure capital project, that straight talk is exactly what you want from the people advising you. We will be using them again on our second site.
This band covers systems from 500 kWp up to 750 kWp, the scale at which a single large roof carries a serious generating asset. As an indicative guide, a system this size runs to roughly 850 to 1,390 commercial modules, takes up roughly 2,500 to 5,250 m² of usable roof and produces in the order of 425,000 to 712,000 kWh a year on a Yorkshire yield. Those figures are engineering rules of thumb, not a promise: your real numbers come from an on-site survey and a PV*SOL model of your roof, its shading and your half-hourly consumption.
It suits the large-footprint operations whose roofs are big enough to host an array of this size and whose electricity demand is heavy enough to use most of the generation on site: regional distribution centres, large logistics sheds, cold storage and food and drink processing. At this scale the engineering is no longer the hard part. The constraints that shape the design are the insurer's view of roof safety and the capacity of the grid connection at your door, and both of those activate squarely inside this band.
OrientationThese are indicative engineering rules of thumb. Your real figures come from an on-site survey and a PV*SOL model of your roof, shading and consumption.
Two design constraints define the 500 to 750 kWp band, and neither is optional.
The first is module-level rapid shutdown. Once an array passes roughly 300 kWp, property insurers increasingly expect the system to meet the RC62 loss-prevention standard, which calls for the ability to de-energise the panels at module level so a roof full of live DC can be made safe for the fire service. Below that scale it is a recommendation; in this band it tends to become a condition of cover. We design RC62-compliant rapid shutdown in from the start, because retrofitting it, or discovering at the survey stage that your insurer requires it, is the kind of surprise that derails a project. It changes the inverter and optimiser strategy and the DC architecture, so it belongs in the first design, not the last.
The second is the grid connection. From around 500 kWp upward, exporting the full output of the array is rarely a given. The local network may not have the headroom to accept it, and the DNO connection offer can come back limited. The engineering answer is export limitation engineered to the G100 standard, which caps what the system pushes onto the network so the connection can still be granted, while you keep the full benefit of the power used on site. Because an exported unit is worth far less than a unit you avoid importing, a well-designed system in this band is built around self-consumption first, with export limitation sized so the grid constraint costs you almost nothing in real return. Whether your connection needs limiting, and at what threshold, is a question the DNO answers, which is why the connection enquiry runs early in the project, not after the panels are ordered.
There is no honest single price for a 500 kW solar system, because two roofs at the same kWp can cost very differently. The figure is built up from the site, and at this scale the cost is driven by the modules and inverters, the mounting system and the way it fixes to your specific roof build-up, the DC and AC cabling runs across a large footprint, the switchgear and the connection into your incoming supply, and access works such as scaffolding or edge protection on a big roof. The grid side is the variable that moves most: a straightforward connection with spare network capacity is one cost, while a connection that needs reinforcement, an export-limitation scheme or new switchgear at the point of supply is another. The RC62 rapid-shutdown requirement also shapes the equipment specification, as covered above.
What does hold true across this band is scale economics. The per-kWp cost falls as the system grows, because the fixed costs of getting a crew and a survey to site, of the design and the connection paperwork, and of the welfare and access setup, are spread across more installed capacity. A 700 kWp array does not cost twice a 350 kWp one. That is why this large-roof band is typically the best value per kWp on a like-for-like roof, stated as a direction rather than a number, since the real figure is always survey-led from the PV*SOL model. For how a system of this size pays back and how it is funded, see our commercial solar ROI and payback guide and the commercial finance routes, where the economics are set out with the proper caveats. We do not put payback years or a per-kWp price on this page.
The 500 to 750 kWp band suits operations with both a large roof and a heavy, steady electrical load, because the return lives in self-consumption. A roof big enough to host this many modules is common on regional distribution centres and large logistics sheds, and the daytime demand of conveyors, automation, lighting and EV charging means much of the generation is used where it is made rather than exported at a low rate.
It fits cold storage and food and drink processing especially well. Refrigeration and process plant draw a large, year-round base load through the working day, which is the load profile that solar offsets most effectively, so a high share of the output is consumed on site and the export constraint matters less. That alignment between a large generating roof and a large on-site demand is what makes this band work. Where your roof is large but your daytime load is lighter, the design leans harder on export limitation and the economics shift, which is exactly the kind of thing the survey and the PV*SOL model are there to test before any commitment.
At this scale you are usually a Type B generator under ENA Engineering Recommendation G99, and a connection of this size frequently lands at high voltage rather than on your low-voltage incomer. That moves the application up a tier: the Distribution Network Operator runs network studies and requires witness testing before it will let the array energise, and the offer that comes back can call for new switchgear, a dedicated cable run or, in a constrained area, reinforcement. In our patch the DNO is Northern Powergrid, which covers Yorkshire and north and north-east Lincolnshire, and the spare headroom on your particular feeder is the single biggest unknown a connection enquiry resolves.
The reformed connections process now weights the queue toward projects that can show readiness, such as planning progress and land or site control, so an early, well-evidenced application tends to move faster than a speculative one. The practical rule at this band is to open the grid conversation before the design is finalised, because the offer shapes the export limit, the switchgear and the programme. The detail sits in our guides to the G99 application and the grid connection queue.
A site hosting an array of 500 to 750 kWp runs on half-hourly settlement metering, so both the import you offset and any surplus you export are measured and settled in half-hour blocks rather than estimated. That granularity makes self-consumption auditable, and it exposes how the system interacts with non-commodity costs. Use of System charges, the distribution DUoS and transmission TNUoS lines on a half-hourly bill, are material at this size and are weighted toward winter peak-demand periods and the red-band hours of the working day. Solar offsets daytime import directly, and pairing the array with battery storage lets a site shift load away from those charged peaks, which is a second layer of value beyond the unit saved. We size that against your own metered profile rather than a sector average, and the half-hourly metering and network-charge questions are set out in full on their own pages.
On the relief side there is one third-party figure worth naming. Solar PV is treated as special-rate plant, and the Annual Investment Allowance gives a 100% first-year deduction within the £1m annual AIA limit, which can bring the relief forward into the year of spend. That is the mechanism, not a promise about your position, because the value depends on your profits and your other capital expenditure, so confirm it with your accountant. We keep no per-kWp price or payback figure on this page; both are survey-led and carried with their assumptions on the finance and ROI pages.
At this scale the array is a long-lived generating asset, so the operations and maintenance regime is designed in with it from the outset. An array of this size carries hundreds of strings, and a single failed string or a tripped inverter can shed a meaningful slice of output unnoticed if nobody is watching the data. That is why a system in this band is commissioned with string-level monitoring and performance-ratio tracking, so an underperforming section flags itself against the modelled yield rather than surfacing months later on a quieter bill. The half-hourly metering already on site, set out above, gives the baseline that monitoring measures against.
The physical regime is modest but real: periodic inverter servicing, thermographic or visual inspection of DC connections, and a cleaning judgement driven by your roof's soiling rather than a fixed calendar. The insurer's RC62 expectation that shapes the build also tends to shape the inspection cadence that keeps cover live. We set this out alongside the commercial O&M and monitoring services and the wider project process, so the maintenance position is clear before you commit.
There is no fixed price, because cost is built up from your specific site. At this scale it is driven by the modules and inverters, the mounting and how it fixes to your roof, the DC and AC cabling across a large footprint, the switchgear and grid connection, and access works such as scaffolding. The grid side moves the figure most: a connection with spare capacity costs less than one needing reinforcement or an export-limitation scheme. Per-kWp cost falls as the system grows, which makes this large-roof band good value, but the real figure is always survey-led from a PV*SOL model of your roof. We do not publish a per-kWp price.
Once an array passes roughly 300 kWp, property insurers increasingly expect it to meet the RC62 loss-prevention standard, which requires the panels to be de-energised at module level so a roof full of live DC can be made safe for the fire service. In the 500 to 750 kWp band this tends to become a condition of cover rather than a recommendation. We design RC62-compliant rapid shutdown in from the first design, because it changes the inverter and DC architecture and is far better engineered in than retrofitted.
Not always. From around 500 kWp upward the local network may not have headroom to accept the full export, and the DNO connection offer can come back limited. The answer is export limitation engineered to the G100 standard, which caps what the system pushes onto the network so the connection can still be granted, while you keep the full benefit of the power used on site. Because exported units are worth far less than imported units you avoid, we design for self-consumption first, so an export limit costs little in real return. Whether you need to limit export, and at what threshold, is for the DNO to confirm, so the connection enquiry runs early.
As an indicative guide, at commercial modules of roughly 540 to 600 W and about 1.7 to 1.85 modules per kWp, a system this size runs to roughly 850 to 1,390 modules. On a flat roof allowing for row spacing, that needs roughly 2,500 to 5,250 m² of usable roof at about 5 to 7 m² per kWp. On a Yorkshire yield of roughly 850 to 950 kWh per kWp a year, expect output in the order of 425,000 to 712,000 kWh annually. These are engineering rules of thumb; your real figures come from an on-site survey and a PV*SOL model of your actual roof, shading and consumption.
The on-roof work for a system this size is typically a matter of weeks once a crew is mobilised, but the programme is paced by the grid rather than the panels. From the moment the design is agreed, the G99 connection application and the Northern Powergrid offer it produces are the longest single lead time, because at this scale the connection often involves high-voltage works, network studies and witness testing. RC62 rapid shutdown and any G100 export limitation are designed in from the start, so they do not add time later. The honest answer is that the connection sets the calendar, which is why the enquiry runs early; our installation timeline guide walks through each stage, and your real dates come from the survey and the connection offer.
These bands are a way to navigate. The system we actually design comes from your half-hourly consumption and an on-site drone survey, modelled in PV*SOL, with the figure built for your site rather than read off a price list.