Many site offices, labour camps, farms, factories and warehouses in the UAE have no connection to the grid, the public power network. They run on diesel generators, and an off-grid solar system can take over much of that work. Diesel cost AED 4.80 a litre in October 2026, up from AED 4.30 in September, according to the UAE's monthly fuel prices. A generator is sized for the busiest hour of the day. For much of the night it runs at low load, which means it supplies only a small share of the power it was built for. At low load it burns more diesel for each unit of electricity it makes.
An off-grid solar system powers a site that has no grid connection. It often works as a hybrid. Solar panels run the site by day and charge a battery for the evening, and a smaller generator is kept as backup. In Dubai, the Dubai Electricity and Water Authority (DEWA) allows off-grid systems in two cases only: emergency backup, or exceptional cases such as remote areas. Even then, you need its written approval. In the other emirates, you write to the local electricity company and ask whether your system needs its approval.
Joseph Smart Solar is a solar installer in Dubai. We design off-grid and hybrid solar systems for sites with no grid, and we are enrolled with DEWA and approved by EtihadWE. Our parent company, Joseph Group, has worked in the UAE since 1979.
Can solar replace a diesel generator on a UAE site?
Yes, for the hours the sun is up, and for the evening if you add a battery. In a hybrid design, a generator smaller than the one you run now is kept as backup. There are three ways to power a site with no grid:
- Generator only. The diesel generator runs day and night. You pay for the fuel and for servicing.
- Hybrid solar system. Panels run the site by day and charge a battery. The battery runs the site in the evening. A controller, the box that manages the system, starts the generator only when the battery runs low. Our team calls this whole setup a PV genset, where PV means solar panels that make electricity and genset means generator.
- Solar with batteries only. There is no generator. This suits small loads that draw the same power all day, such as lights, signs and cameras. A load is any machine, light or AC unit that uses power.
Both solar setups depend on the battery. DEWA's own FAQ says that off-grid systems depend on rechargeable batteries to store spare power, while systems connected to the grid do not need storage.
What does a diesel generator really cost to run?
A 180 kW diesel generator that runs at a quarter of its power for 12 hours a night burns about 199 litres. At the October 2026 price of AED 4.80 a litre, that is about AED 956 a night. A kilowatt (kW) measures how much power a machine supplies or uses at one moment.
Those figures come from the US generator maker Kohler, which publishes fuel use for its 180 kW generator, model 180REOZJG. They show why low load costs more:
- At full load, it makes 180 kW from 51.8 litres an hour. That is about 3.47 kWh for each litre. A kWh is the unit of electricity on a power bill.
- At quarter load, it makes 45 kW from 16.6 litres an hour. That is about 2.71 kWh for each litre.
- So at quarter load, each kWh needs about 28% more diesel (3.47 ÷ 2.71 = 1.28).
Low load also harms the engine. Running a diesel engine at light load for long periods sends unburned fuel and soot into the exhaust. This fault is called wet stacking, as the US engineering magazine Consulting-Specifying Engineer explains. NFPA 110, the US standard for emergency generators, asks for monthly tests at 30% or more of the generator's full rated power to prevent wet stacking. The usual cure is a few hours of running at about 75% of full power.
Your own figures will differ. Before you compare a solar quote with your generator, collect three numbers for the last three months:
- Litres of diesel delivered to site, from the delivery notes.
- What you paid for generator rental or servicing.
- Hours the generator ran: the running hours shown on its control panel today, minus the hours in your service record from three months ago.
Multiply the litres by the price you paid per litre, from your diesel invoices. Add the rental or servicing cost, and divide by three to get your generator's monthly cost. To find your litres per hour, divide the litres by the hours.
How much of the generator's work can solar take over?
Solar can take over everything your site runs in daylight, and the evening too if you add a battery. Site office air conditioning, tools, water pumps and lights in working hours all match the hours the sun is up.
You can estimate what panels will make. kWp, or kilowatt peak, is the most power a set of panels makes in full sun. The Global Solar Atlas, a free online solar map, gives about 1,792 kWh a year for each kWp in Dubai. Fujairah's figure is almost the same, about 1,789. That works out to about 4.9 kWh a day for each kWp, as a yearly average.
Evening and night loads need a battery. A battery energy storage system stores spare daytime power and releases it after sunset. Loads that run all night, such as cold rooms or dormitory air conditioning in a labour camp, need a large battery or the generator. Solar can still run them by day, so the generator runs fewer hours.
When the generator does run, it can also charge the battery. It then works closer to full load, where each litre makes more electricity.
Which sites suit off-grid or hybrid solar, and which do not?
Off-grid and hybrid systems work best where a site needs power for many months and has space for panels. Good fits include:
- Site offices and porta cabins on projects that run for a year or more.
- Labour camps, where solar can run daytime loads such as the camp office, kitchen and laundry.
- Farms, where a pump can fill a water tank in daylight, so the tank stores water instead of a battery storing power.
- Factories and warehouses on industrial plots still waiting for a grid connection.
- Cold rooms and chillers on a generator, with solar covering the daytime hours.
- Signs, cameras and lights far from the grid.
Keep the generator as the main source in these cases:
- The site closes before a solar system could be designed, approved and installed. Ask your installer how long that takes for your site.
- Your grid connection will arrive before solar could be approved and installed. Compare your installer's timeline with the date your electricity company gave you.
- Heavy loads run around the clock and there is not enough space for panels. Work out your kWp with step 4 of the sizing steps below, then ask your installer how much roof or ground area your panels need.
What approvals does an off-grid solar system need in the UAE?
In Dubai, DEWA allows off-grid systems only in narrow cases and only with its written approval. In the other emirates, write to the local electricity company before you install, and ask whether your system needs its approval.
Dubai. DEWA's 2025 connection conditions are its rules for connecting power systems. They say that no one other than DEWA may generate power with an off-grid system in Dubai, whether the source is diesel, solar or anything else. There are two exceptions: backup power during emergencies, and exceptional cases such as remote areas, with DEWA's prior written approval. DEWA must also approve the design. In practice:
- Choose a solar contractor on DEWA's enrolled list, the installers DEWA allows to fit solar systems in Dubai. Our list of solar companies in UAE shows how to check the list.
- Ask the contractor to apply to DEWA for written approval to run an off-grid system on your site. Give them the site location and your load list from the sizing steps below.
- Ask the contractor to submit the system design to DEWA for approval.
- Do not buy panels or batteries until both approval letters arrive. Keep the letters on site.
If a diesel generator already runs on your site, ask the contractor to include it in the same application, so DEWA can say whether it may stay as backup.
The Northern Emirates. Etihad Water and Electricity (EtihadWE) is the electricity company for the Northern Emirates. Its Distributed Solar System is a programme for rooftop solar connected to the grid, and its conditions say an approved contractor must install it. They do not cover off-grid systems. Before you install an off-grid system, write to EtihadWE through the contact page on its website, and ask whether your site needs its approval. Keep its reply with your site records.
Abu Dhabi and Sharjah. Before you install, write to TAQA Distribution in Abu Dhabi or to SEWA (Sharjah Electricity, Water and Gas Authority) in Sharjah. Use the contact page on its website, and ask whether your off-grid system needs its approval. Keep the reply with your site records.
How do you size solar and batteries to replace a generator?
You can make a first estimate from a list of what runs on site:
- List every load. Read the input power in watts on each unit's label. On an AC, use the input power, not the cooling capacity, which is a much bigger number. One 2-ton split AC sold in the UAE lists 1,983 W of input power. If a label shows kW, multiply by 1,000. If it shows only amps, send a photo of the label to your installer.
- Write down the hours each load runs, split into daytime and night.
- Work out the energy. Multiply watts by hours, then divide by 1,000 to get kWh. Keep two totals: one for daytime, one for night.
- Estimate the panels. Add the daytime and night kWh, because the panels also charge the battery. Divide the total by 4.9, the kWh each kWp of panels makes on an average day in Dubai or Fujairah. Use the same 4.9 for a first estimate in the other emirates. The answer is the kWp of panels you need. Ask your installer what margin they add for dust and hazy days.
- Estimate the battery. Look for a battery that can supply at least your night kWh each night. Ask your installer how much extra capacity they add.
- Size the backup generator. Pick the loads that must keep running when the battery is empty, such as a cold room or a water pump. Add their watts and divide by 1,000 to get kW. Generators are rated in kVA (kilovolt-amperes). To convert kVA to kW, multiply by 0.8. To go the other way, divide the kW by 0.8 to get the kVA to ask for. Kohler's 180 kW generator is rated at 225 kVA (180 ÷ 0.8 = 225).
Here is a worked example, based on a site office enquiry we received from Ajman. The office has two 2-ton split ACs and 12 LED lights of 15 W each, and it is open 10 hours a day.
- The two ACs at about 2 kW each, for 10 hours, use about 40 kWh.
- The 12 lights at 15 W, for 10 hours, use about 1.8 kWh.
- If both ACs run for 2 more hours after sunset, the battery must supply about 8 kWh.
- Day and night together come to about 50 kWh, so the panels need about 10 kWp (50 ÷ 4.9 = 10.2).
This is a first estimate. A site survey then checks the real loads and the space for panels.
If you would rather not do the sums yourself, send us your load list, and we will size the system as part of our free site survey.
How do UAE heat and dust affect panels and batteries?
Heat matters most for the battery. Huawei's LUNA2000-215 commercial battery works from minus 30 °C to 55 °C and reduces its output above 50 °C. Ask for the datasheet of any battery you are offered. The operating temperature line shows where its output starts to drop, and if the datasheet leaves this out, ask the installer for the figure in writing. Then ask how the battery will be kept below that temperature in August, such as in shade or in a cooled container.
Dust matters most for the panels. A dusty panel makes less power. Before you buy, ask your installer who cleans the panels, how often, and whether cleaning is in the price.
How does diesel show up in your company's emissions report?
The UAE's climate law, Federal Decree-Law No. 11 of 2024, came into force on 30 May 2025. It requires companies to measure and report their emissions, and fines for breaking it go up to AED 2 million. Every litre of diesel adds to that report. The US Environmental Protection Agency gives 10.21 kg of CO2 for each US gallon of diesel, which is about 2.7 kg for each litre.
The 180 kW generator in the example above, burning 199 litres a night, adds about 16 tonnes of CO2 a month. Every hour of power that solar supplies instead of diesel lowers the emissions you report.
What should you ask before you buy an off-grid or hybrid system?
Ask these questions, and get each answer in writing:
- Which approvals does this system need, and who applies? In Dubai, ask to see DEWA's written approval and the approved design before work starts.
- Can the controller, the box that runs the system, start and stop the backup generator? If not, ask what has to change, and what that costs.
- How many kWh can the battery supply each night? The answer should be at least the night kWh from step 3 of the sizing steps.
- At what temperature does the battery's output drop, and where will the battery sit? Ask how it will be kept below that temperature in August.
- How will I see the system's output each day? Ask who gets an alert when output drops, and how fast they respond.
- When the grid reaches my site, can this system connect to it? Ask which approval that needs.
- If the site closes, can the panels and battery move to my next site? Ask who moves them and who reconnects them.
How does Joseph Smart Solar plan an off-grid or hybrid system?
We start with a free site survey. Before the visit, please send the generator's size, three months of fuel records, and a list of what runs on site and when.
From there, our team:
- Checks the loads and the space for panels on site.
- Designs the panels, battery and backup generator as one system.
- Applies for the approvals your emirate requires.
- Installs the system with our own team.
- Monitors it after switch-on, so we get an alert if output drops.
For two government schools in Abu Dhabi and Al Ain, we installed 92 off-grid solar signs, each running on its own panel and battery. You can see this on our projects page.
If your site runs on a diesel generator, send us those details. We will tell you how much of that load solar can carry.
Frequently asked questions
Is a solar generator the same as a hybrid solar system?
No. A solar generator is usually a portable box with a small battery, charged from a panel and sized for a few lights or a phone. A hybrid solar system for a site is fixed equipment: rows of panels, a set of batteries and a diesel generator. One control box decides which of them powers the site, and the system is designed around the site's real power use, such as air conditioning, pumps and cold rooms.
Can solar run air conditioning at night?
Yes, but only from a battery. Panels do not make power after sunset, so every hour of night cooling must be stored during the day. One 2-ton split AC sold in the UAE lists 1,983 W of input power. Two of them running for two hours need about 8 kWh from the battery. Long, heavy night loads are usually cheaper to run on the generator.
Do batteries cope with UAE summer heat?
They can, if they are kept cool. Huawei's LUNA2000-215 commercial battery works from minus 30 °C to 55 °C and reduces its output above 50 °C. Ask the installer for the battery's datasheet and the temperature where its output starts to drop. Then ask how the battery will be kept below that in August, such as in shade or in a cooled container.
Do I need DEWA approval for an off-grid solar system in Dubai?
Yes. In Dubai, only the Dubai Electricity and Water Authority (DEWA) may generate power with an off-grid system. The exceptions are emergency backup and exceptional cases such as remote areas, and both need DEWA's written approval. DEWA must also approve the design. Choose a contractor on DEWA's enrolled list, the installers DEWA allows to fit solar systems in Dubai. Ask them to apply for both approvals, and do not buy panels or batteries until both letters arrive.
What size generator do I still need with solar?
Size it for the loads that must keep running when the battery is empty, not for every machine on site. Add their watts and divide by 1,000 to get kW. Generators are rated in kVA (kilovolt-amperes), so divide the kW by 0.8 to get the kVA to ask for. The US maker Kohler rates one of its generators at 180 kW and 225 kVA. A smaller generator working close to its full power uses less fuel for each kWh it makes.