{"id":2284,"date":"2026-08-01T11:42:00","date_gmt":"2026-08-01T08:42:00","guid":{"rendered":"https:\/\/mits.sa\/%d9%86%d8%b8%d8%a7%d9%85-%d8%a7%d9%84%d8%b7%d8%a7%d9%82%d8%a9-%d8%a7%d9%84%d8%b4%d9%85%d8%b3%d9%8a%d8%a9-%d8%a7%d9%84%d9%85%d9%86%d9%81%d8%b5%d9%84\/"},"modified":"2026-10-17T08:29:48","modified_gmt":"2026-10-17T05:29:48","slug":"off-grid-solar-system","status":"publish","type":"post","link":"https:\/\/mits.sa\/en\/off-grid-solar-system\/","title":{"rendered":"Off-grid solar power system: When do you need it and how is it designed?"},"content":{"rendered":"<p>An off-grid system is a solar power system completely independent of the electrical grid. It generates electricity from panels during the day and stores it in batteries for use at night. It&#039;s needed when the grid doesn&#039;t reach your location or when connection is impractical. It&#039;s designed in five basic steps: load assessment, panel calculations, battery selection, inverter selection, and finally, cabling and protection.<\/p>\n<div class=\"mits-box\"><strong>In short:<\/strong><\/p>\n<ul>\n<li>An off-grid system is suitable for farms, rest areas, camps, and remote locations, and is not the most economical option for a home with network access.<\/li>\n<li>The design starts from the daily load schedule in watt-hours, not from the number of panels.<\/li>\n<li>Batteries are calculated based on nighttime consumption and the allowed depth of discharge, and panels are calculated based on the worst days of the year.<\/li>\n<li>Moving heavy loads to daytime use reduces the size of batteries and greatly lowers costs.<\/li>\n<\/ul>\n<\/div>\n<h2>When do you really need an off-grid system?<\/h2>\n<p>A separate system is an excellent solution in its proper place, and unnecessarily expensive in others. Situations where it is the logical choice:<\/p>\n<ul>\n<li>A farm or well located far from power lines, as in the outskirts of Qassim, Tabuk and Al-Ahsa.<\/li>\n<li>A wilderness retreat or winter camp used during specific seasons.<\/li>\n<li>Locations where laying a new power line is longer and more difficult than installing an independent system.<\/li>\n<li>Small loads in remote locations: surveillance cameras, gate lighting, communication and monitoring devices.<\/li>\n<\/ul>\n<p>However, if the network is available and stable, a tethered or hybrid system will often give you a better return. We compared the three types with figures in the article. <a href=\"\/en\/on-grid-vs-off-grid-vs-hybrid\/\">The difference between On-Grid, Off-Grid and Hybrid solar power systems<\/a>.<\/p>\n<h2>Step 1: Daily Load Schedule<\/h2>\n<p>Every sound design begins with the question: How many watt-hours does it consume per day? List each device, its power in watts, and the number of hours it operates, then multiply the power by the hours. We&#039;ll take a rest area in Qassim as an example; the figures are hypothetical for illustrative purposes.<\/p>\n<table class=\"mits-t\">\n<thead>\n<tr>\n<th>The device<\/th>\n<th>Power<\/th>\n<th>Operating hours<\/th>\n<th>Daily consumption<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>LED lighting (10 bulbs x 20 watts)<\/td>\n<td>200 watts<\/td>\n<td>6<\/td>\n<td>1200 watt-hours<\/td>\n<\/tr>\n<tr>\n<td>Refrigerator (estimated daily average)<\/td>\n<td>\u2014<\/td>\n<td>24<\/td>\n<td>1500 watt-hours<\/td>\n<\/tr>\n<tr>\n<td>television<\/td>\n<td>100 watts<\/td>\n<td>5<\/td>\n<td>500 watt-hours<\/td>\n<\/tr>\n<tr>\n<td>Routers and chargers<\/td>\n<td>15 watts<\/td>\n<td>24<\/td>\n<td>360 watt-hours<\/td>\n<\/tr>\n<tr>\n<td>18000 BTU Split Air Conditioner<\/td>\n<td>1800 watts<\/td>\n<td>6<\/td>\n<td>10800 watt-hours<\/td>\n<\/tr>\n<tr>\n<td>1 HP water pump<\/td>\n<td>746 watts<\/td>\n<td>1<\/td>\n<td>Approximately 750 watt-hours<\/td>\n<\/tr>\n<tr>\n<td><strong>the total<\/strong><\/td>\n<td><\/td>\n<td><\/td>\n<td><strong>15110 watt-hours \u2248 15.1 kilowatt-hours<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Note that the air conditioner alone accounts for more than 70% of consumption (10.8 \u00f7 15.1). This is normal in our climate, which is why every decision regarding air conditioning affects the overall system.<\/p>\n<h2>Step 2: Calculate the number of panels<\/h2>\n<p>A kilowatt of solar panels in Saudi Arabia produces approximately 4.5 to 6 kilowatt-hours per day. In a split system, we design for the lower end (4.5) because winter days are shorter, and we add an approximate margin of 20% for losses related to battery charging and discharging, cables, and dust.<\/p>\n<ul>\n<li>Basic power: 15.1 \u00f7 4.5 \u2248 3.36 kW.<\/li>\n<li>After the margin: 3.36 \u00f7 0.8 = 4.2 kW.<\/li>\n<li>With 550W panels: 4200 \u00f7 550 \u2248 7.6, i.e., 8 panels (4.4 kW).<\/li>\n<li>Area: 4.4 \u00d7 5 to 6 m\u00b2 = approximately 22 to 26 m\u00b2.<\/li>\n<\/ul>\n<p>Orient the panels towards the south at an angle close to the site&#039;s latitude, approximately 26\u00b0 in Al-Qassim. If they will be installed on the ground or a roof, calculate the appropriate structure via <a href=\"\/en\/solar-mounting-structure-calculator\/\">Solar Mounting Structure Calculator<\/a>.<\/p>\n<h2>Step 3: Calculate battery capacity<\/h2>\n<p>Batteries are not charged based on total daily consumption, but rather on consumption when there is no sunlight. In our example, we assume the nighttime loads are: lighting 1.2 kWh, television 0.5 kWh, half the refrigerator&#039;s consumption 0.75 kWh, half the router&#039;s consumption 0.18 kWh, and three hours of air conditioning 5.4 kWh. The total is approximately 8 kWh.<\/p>\n<p>Next, we divide by the allowable discharge depth and the inverter efficiency (we take 95%):<\/p>\n<ul>\n<li>Lithium phosphate (LiFePO4) at a depth of 90%: 8 \u00f7 0.9 \u00f7 0.95 \u2248 9.4 kWh. On a 48V system: 9400 \u00f7 48 \u2248 196, i.e., a battery of approximately 200 Ah.<\/li>\n<li>Gel or lead with a depth of 50%: 8 \u00f7 0.5 \u00f7 0.95 \u2248 16.8 kWh, which is about 350 amp-hours at 48 volts.<\/li>\n<\/ul>\n<p>If you want a spare day for dusty days, multiply the result by 2. Remember that lithium can withstand approximately 3,000 to 6,000 cycles compared to 500 to 1,500 cycles for gels; the difference in lifespan compensates for a large part of the price difference. Details are in my article. <a href=\"\/en\/solar-battery-sizing\/\">Calculating battery capacity for nighttime operation<\/a> \u0648<a href=\"\/en\/solar-batteries-lithium-vs-gel\/\">Solar batteries: Lithium or gel?<\/a>.<\/p>\n<h2>Step 4: Choosing the inverter and charge controller<\/h2>\n<p>The inverter is selected based on the highest load operating at any given moment, not on daily consumption. In our example, it might be operating simultaneously: an air conditioner (1800 watts), a pump (746 watts), and a refrigerator, lights, and television (approximately 450 watts). The total is approximately 3 kilowatts.<\/p>\n<p>However, motors (air conditioner compressors, refrigerators, and pumps) draw several times the operating current at startup, especially non-inverter-driven devices. Therefore, an inverter of approximately 5 kW with a suitable starting current rating is recommended. The charge controller should ideally be an MPPT type and must be compatible with the voltage and current of the power supply panels. Many modern off-grid inverters come with a built-in MPPT charge controller.<\/p>\n<h3>Why is a 48-volt system preferred?<\/h3>\n<p>Because the current decreases as the voltage increases. A 3000-watt load on 12 volts requires 3000 \u00f7 12 = 250 amps, while on 48 volts it requires only 62.5 amps. Lower current means thinner cables, less heat, and less loss. 12-volt systems are only suitable for very small loads.<\/p>\n<h2>Step 5: Cables, protection, and installation location<\/h2>\n<ul>\n<li>Suitable DC fuses and circuit breakers between the panels and the regulator, and between the batteries and the inverter.<\/li>\n<li>Cables with a cross-section that can withstand current with limited voltage drop, especially between the battery and the inverter where the current is highest.<\/li>\n<li>Grounding of structures and inverters, and protection from lightning strikes in exposed locations.<\/li>\n<li>A shaded and well-ventilated room for the batteries and inverter, because summer heat shortens the life of the batteries.<\/li>\n<li>Sturdy structures that can withstand winds, and hot-dip galvanized steel is preferred in exposed locations.<\/li>\n<\/ul>\n<div class=\"mits-tip\"><strong>\ud83d\udca1 Tip:<\/strong> Shift heavy loads to sunnier times: run the water pump and washing machine, fill the top tank at midday, and cool the rest area thoroughly before sunset. Every kilowatt-hour you shift from night to day saves you approximately one kilowatt-hour of battery capacity.<\/div>\n<h2>Common errors in off-grid systems<\/h2>\n<ul>\n<li><strong>Reducing the size of the batteries to lower the price:<\/strong> It is emptied to a great depth daily and its lifespan is shortened.<\/li>\n<li><strong>Design based on the average year:<\/strong> The system works well in the summer but malfunctions in the winter or after dust storms.<\/li>\n<li><strong>Ignore the takeoff stream:<\/strong> The inverter switches off whenever the pump or air conditioner is running.<\/li>\n<li><strong>Mixing old batteries with new ones<\/strong> Or different types in one bank.<\/li>\n<\/ul>\n<p>For farms whose main goal is water extraction, there is often a simpler solution that doesn&#039;t require batteries: <a href=\"\/en\/solar-system-pump\/\">Solar agricultural submersible pump systems<\/a> Which pumps water during the day and stores it in a tank instead of storing electricity. To determine the initial size of your system, try <a href=\"\/en\/solar-energy-calculator\/\">Solar system size calculator<\/a>Or learn design on your own at <a href=\"\/en\/learn\/?course=solar\">Solar System Design Course<\/a>.<\/p>\n<h2>Frequently Asked Questions<\/h2>\n<div class=\"mits-faq\">\n<h3>Can I run an air conditioner all night in off-grid mode?<\/h3>\n<p>Technically possible, but an 18,000 BTU air conditioner consumes approximately 1.8 kilowatt-hours per hour, so ten hours of nighttime use means about 18 kilowatt-hours from the batteries alone. This significantly increases the system&#039;s size and cost, so it&#039;s better to reduce nighttime operating hours or choose a more energy-efficient air conditioner.<\/p>\n<h3>How many days of battery life do I need?<\/h3>\n<p>For a break used on weekends, one day with some leeway is often sufficient. However, sensitive loads that cannot tolerate downtime may require two days or a backup generator to charge the batteries when needed.<\/p>\n<h3>What happens to excess electricity when batteries are full?<\/h3>\n<p>In a separate system, there is no grid to receive excess power, so the regulator reduces the load and this output is lost. Therefore, it is advisable to operate flexible loads such as pumps and water heaters during these times.<\/p>\n<h3>Can panels and batteries be added later?<\/h3>\n<p>Yes, if the inverter and charge controller can handle the additional power. As for the batteries, it&#039;s preferable to use the same type and specifications, and to add them as early as possible so that their lifespan doesn&#039;t differ significantly from the existing batteries.<\/p>\n<\/div>\n<div class=\"mits-cta\">\n<p><strong>Do you need a suitable system?<\/strong> The MITS team designs and installs off-grid systems for farms, rest areas, and remote sites, from load scheduling to galvanized structures manufactured in our factory.<\/p>\n<p><a href=\"\/en\/contact\/\">Request a price quote<\/a> \u00b7 <a href=\"https:\/\/wa.me\/966575993880\">WhatsApp 0575993880<\/a> \u00b7 <a href=\"\/en\/solar-energy-calculator\/\">Try the calculator<\/a><\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>A step-by-step guide to designing an off-grid system: load counting, panel calculations, batteries, and inverters, with a practical example for a break in Al-Qassim and when you actually need this system.<\/p>","protected":false},"author":1,"featured_media":2283,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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Design","seo_description":"","seo_description_en":"Off-grid solar design step by step: load list, panel, battery and inverter sizing, with a worked example for a rest house in Qassim."},"categories":[40],"tags":[143,54],"class_list":["post-2284","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-40","tag-143","tag-54"],"acf":[],"_links":{"self":[{"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/posts\/2284","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/comments?post=2284"}],"version-history":[{"count":1,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/posts\/2284\/revisions"}],"predecessor-version":[{"id":2348,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/posts\/2284\/revisions\/2348"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/media\/2283"}],"wp:attachment":[{"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/media?parent=2284"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/categories?post=2284"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mits.sa\/en\/wp-json\/wp\/v2\/tags?post=2284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}