Solar PV for Facilities: Why Design Should Not Start with Roof Area

Solar PV for Facilities: Why Design Should Not Start with Roof Area When a company considers solar PV, the first question is often: How many panels can we fit on the roof? It is a reasonable question, but it is not the correct engineering starting point. The objective is not to fill every available square meter with panels. The objective is to design a generation system that matches: facility consumption, load profile, operating hours, grid conditions and project economics. Solar design therefore begins with energy demand, not roof area. Start with Facility Consumption Before defining plant capacity, understand: - Annual electricity consumption - Seasonal variation - Daily load profile - Peak demand - Daytime vs nighttime use - Planned future loads - Expansion plans A single electricity bill cannot provide this picture. Twelve months of data is a much stronger starting point. Why Load Timing Matters Two facilities can consume the same amount of electricity annually but require very different solar strategies. A factory operating mainly during daylight may consume solar generation directly. A hotel operating 24/7 may have significant evening and overnight loads. The question is therefore not only: How much electricity is consumed? It is also: When is it consumed? Load Profile Matters Annual consumption provides total volume. A load profile provides operating behavior. It helps identify: - Base demand - Peak demand - Day/night patterns - Seasonal loads - Weekday/weekend differences - HVAC impacts These factors influence both plant size and project economics. What Happens If We Design from Roof Area Alone? A system may become oversized relative to demand. This can create: - unnecessary CAPEX - unused generation - export limitations - curtailment - longer payback Or the opposite may occur: roof area may appear too small while alternative generation options exist. These can include: - ground-mounted systems - solar carports - solar canopies - wheeling - remote generation - storage where justified The roof is therefore a design constraint—not the complete strategy. Zero Export Some grid arrangements do not permit electricity export. A Zero Export system controls generation so that power does not flow back into the grid. This makes load-profile analysis critical. If PV capacity greatly exceeds daytime demand, the plant may frequently curtail generation. Wheeling When the consuming facility cannot host a sufficiently large solar plant, generation may be developed at another suitable location and transferred through the grid under an approved wheeling arrangement. This enables project capacity to be determined by energy needs rather than by the physical limitations of one building. Hyatt Regency Ayla Example For Hyatt Regency Ayla, the resort site in Aqaba could not accommodate the required solar plant. The system was therefore developed in Quweira and energy transferred to the resort through a wheeling arrangement. The plant capacity is approximately: 1.3 MWp DC and: 965 kW AC with annual generation of approximately: 3.0 GWh Single-axis tracking was used to improve solar capture and plant productivity. The engineering decision therefore involved more than panel quantity. It integrated: location + plant capacity + tracking + energy-transfer strategy. kWp, kW and kWh These terms are often confused. kWp represents rated PV module capacity under defined test conditions. kW represents instantaneous power. kWh represents energy produced or consumed over time. A 1 MWp plant does not continuously produce 1 MW. Annual output depends on multiple factors. DC vs AC Capacity PV module DC capacity does not always equal inverter AC capacity. The relationship is often described through the: DC/AC Ratio The correct ratio depends on: - climate - generation profile - module cost - inverter characteristics - grid constraints - economic objectives DC oversizing can be an intentional engineering decision. Fixed Tilt vs Tracking Fixed-tilt systems are mechanically simple and often cost-effective. Tracking systems such as Single-Axis Tracking can increase energy capture throughout the day. However, tracking adds: - mechanical systems - land requirements - maintenance - additional CAPEX The decision should therefore be based on incremental economic value, not energy production alone. Do You Need Batteries? Not every solar project needs storage. The first question should be: What problem would the battery solve? Possible objectives include: - backup - peak-demand reduction - self-consumption improvement - off-grid operation - storing surplus generation Where daytime consumption is strong and grid supply is reliable, PV without batteries may provide a stronger business case. Solar PV May Not Be the First Step In many facilities, the better energy sequence is: Reduce consumption → Electrify suitable thermal loads → Recalculate demand → Design renewable generation If avoidable consumption exists, installing PV first may mean investing in generation to supply energy that could have been eliminated. Solar PV and Heat Pumps Converting a thermal load from diesel or gas to heat pumps reduces fuel consumption but increases electrical demand. This new electrical load can then be partially offset with solar PV. For this reason, electrification and renewable generation should often be evaluated together. Project Economics PV feasibility can include: - CAPEX - annual generation - electricity offset value - O&M - module degradation - inverter replacement - land cost - grid fees - payback - NPV - IRR The important part is making assumptions transparent. Highest Generation Does Not Always Mean Best Project More annual generation can look attractive, but it may not create the best financial result. The strongest project balances: generation + utilization + CAPEX + grid constraints + operating risk. Data Required Before Solar Design Useful inputs include: - 12 months of electricity bills - demand readings - operating hours - electrical drawings - single-line diagrams - roof or land availability - site photographs - future loads - planned heat pumps - planned EV charging - grid information Better input data leads to better design. Common Solar PV Mistakes Common mistakes include: - starting with panel count - ignoring future loads - using one month of consumption - ignoring system losses - ignoring shading - overlooking interconnection limits - assuming batteries are always necessary - failing to include monitoring and O&M Why Monitoring Matters A PV plant may appear physically healthy while suffering from: - string faults - inverter issues - soiling - shading - communication problems - underperformance Monitoring allows these issues to be identified before months of generation are lost. How Is Performance Verified? Measured generation should be compared against expected performance while considering: - solar irradiation - weather - availability - outages - plant condition The same engineering principle used in M&V for efficiency projects applies to renewable generation: performance should be measured, not assumed. Conclusion Solar PV design should not begin with: How many panels fit on the roof? It should begin with: How much energy does the facility use? When does it use it? What future loads are expected? What grid constraints apply? Can consumption be reduced first? And where is the best location to generate? Roof area comes later as one of many design variables. At Perfect Solutions Engineering, solar PV is treated as part of the facility’s complete energy system—not as a standalone array. The objective is not to install the largest plant possible. The objective is to engineer the right plant for the actual energy demand.