The cost of a solar power system is primarily determined by three factors: the system's size in kilowatts, its type (grid-tied, hybrid, or off-grid), and whether or not batteries are included. Other contributing factors include the type of panels and inverter, the appropriate rooftop mounting structure, cable length, site complexity, and the level of warranty and after-sales service.
- The size of the system is determined by your consumption and the coverage percentage you want, and this is the first thing that raises or lowers the cost.
- Batteries are often the largest single item in hybrid and separate systems.
- The installation structure varies depending on the surface: concrete, metal, ground, elevated, or carport.
- Two offers with the same number of kilowatts may differ greatly due to the quality of the components, the warranty, and the range of work.
- The best way to reduce costs is to design correctly from the start, not to choose the cheapest component.
Why do solar energy pricing quotes differ for the same size?
Many people ask: I received two offers for a 10 kW system, so why is there such a big difference between them? The answer is that the kilowatt number describes the power of the panels only, and does not say anything about the type of inverter, the presence of batteries, the type of structure and the thickness of its iron, the length of the cables and their protection, or whether installation, permits and operation are included in the price or not.
Therefore, don't compare offers based solely on the total price. Compare the component list item by item, the scope of work, warranties, and who is responsible for post-commission maintenance.
Key factors that determine the cost of a solar system
1. System size and coverage ratio
The higher your daily electricity consumption, the more panels, inverter size, and cable length you'll need. However, a 100% system won't necessarily cover your entire consumption; some people start by covering part of their bill and then expand later. This decision directly impacts the cost. Generally, the cost per kilowatt-hour decreases with increasing size because some expenses, such as design, operation, and transportation, don't double with increasing size.
2. System type: Tied, Hybrid, or Split
A grid-tied (on-grid) system without batteries is usually the simplest. A hybrid system adds batteries and a hybrid inverter. An off-grid system requires batteries sufficient for the entire night and several days of backup power, and more solar panels because it's designed for the weakest month of the year. The differences between the three systems are explained in the article. The difference between On-Grid, Off-Grid and Hybrid solar power systems.
3. Batteries: Type and Capacity
Battery capacity is calculated based on nighttime usage and the required number of hours of standby time. Lithium batteries differ from gel batteries in lifespan and permissible depth of discharge, which affects the nominal capacity you need to purchase to obtain the same usable power. The calculation method is detailed in [the relevant section/context]. Calculating battery capacity for nighttime operation.
4. Panel type and capacity
High-efficiency monocrystalline and bifacial panels differ from others in their output per square meter. If your surface area is limited, the higher-efficiency panel may be more efficient overall because it provides a greater output from the same area.
5. Inverter: Type, Brand, and Phase
The inverter is the brain of the system. It varies depending on whether it's on-grid or hybrid, single-phase or three-phase, and also on the brand and its monitoring and protection features. An inverter that's too large increases costs unnecessarily, while one that's too small wastes panel production.
6. Mounting structure and surface type
Concrete roofs require a sloping structure with foundations or weights, while metal roofs require a lightweight structure supported by sheet metal. Ground-level installations require concrete foundations, and elevated structures and carports require more steel and longer columns. The type of metal (hot-dip galvanized steel or aluminum) and its thickness also affect the choice. Learn more about the options in [link/context missing]. Solar panel mounting structures.
7. Cables, protection, and grounding
The distance between the panels, the inverter, and the electrical panel increases, as does the length and cross-section of the cables. In addition, circuit breakers, lightning protection, and the grounding system are essential components that cannot be skimped on because they protect the system and the building.
8. Location and difficulty of installation
A high roof requires a crane, a farm far from the city, or an operational facility that cannot be shut down during installation; all of these increase time and effort. Projects requiring civil works such as excavation and foundations differ from installing a prefabricated roof.
9. Permissions and Network Connection
The grid-connected system undergoes procedures and approvals according to the requirements set by the relevant authorities (such as the Saudi Electricity Company and the Electricity Regulatory Authority). This may include approved components and a suitable meter. Confirm whether these procedures are included in the offer or the customer's responsibility.
10. Warranty, maintenance and after-sales service
An offer that includes a warranty on installation, maintenance visits, and production follow-up differs from an offer that only provides the supply. The price difference often reflects the difference in the contractor's post-commission responsibility.
Table: The impact of each factor on cost and how to save on it intelligently
| worker | Its impact on cost | How to save without harming the system |
|---|---|---|
| System size | Very large | Reduce consumption first (insulation, energy-efficient appliances), then adjust to actual consumption. |
| batteries | Large in hybrid and separate | Calculate only the actual nighttime consumption; do not add batteries for loads that can be operated during the day. |
| System type | big | If the network is available and stable, a tethered system is often the simplest. |
| inverter | middle | Choose the appropriate capacity for the panels and loads; not too large and not too small. |
| Fixture structure | middle | Choose the appropriate type for the surface, and only use a raised structure if space underneath is needed. |
| Cables and protection | small to medium | Position the inverter close to the panels, and do not compromise on protection and grounding. |
| Warranty and Maintenance | small to medium | Compare what the warranty actually covers and its duration, not just the presence of the word "warranty". |
Illustrative example: How the system type changes the component list for the same house
Let's assume a household consumes approximately 40 kilowatt-hours per day, with about 10 kilowatt-hours consumed after sunset. The following figures are approximate and intended to illustrate how the list of components expands, not to provide a price.
- Networked system: The system requires approximately 9–10 kW panels (around 18 panels at 550 watts each), a suitable on-grid inverter, a frame, cables, and protection. At night, the house is powered by the grid.
- Hybrid system: The panels are almost identical, but with a hybrid inverter and batteries for overnight use. The required capacity is ≈ 10 ÷ (0.9 DPD × 0.95 Efficiency) ≈ 11.7 kWh of lithium batteries.
- Separate system: Batteries for night and at least one day of backup, approximately two to three times the capacity of the hybrid, more panels by approximately 20% to cover short days and dust, and an inverter that can handle the starting current of all loads off-grid.
The example shows that switching from grid-tied to hybrid only added one major component—batteries—while switching to off-grid doubled the number of batteries and increased the number of solar panels. Therefore, the first question you should answer before requesting a quote is: Do you actually need off-grid operation, or do you simply want to reduce your bill?
How do you read a price quote and compare offers?
- Total panel capacity, number, and brand The capacity of a single tablet.
- Inverter type, power, and phase Does it support adding batteries in the future?.
- Batteries: Type, nominal capacity, and usable capacity.
- Structure: Its type, material, galvanizing method, and method of installation on your surface.
- Electrical work: Cables, circuit breakers, lightning protection, grounding.
- Scope of work: Supply, installation, commissioning, connection procedures, monitoring training.
- Expected annual production In kilowatt-hours, that is what determines the true value of the system.
- Guarantees and maintenance: The duration, what it includes, and who provides it.
A quote that doesn't mention expected output or omits protection and grounding warrants further inquiry before comparison. Once the cost is determined, the next step is: Calculating the solar energy cost payback periodThen report Is solar energy worthwhile? For your situation.
Mistakes that raise costs without any benefit
- Enlarging the system based on guesswork: Instead of relying on invoices for a whole year.
- Adding unnecessary batteries: In a location with a stable network, the goal is simply to reduce the bill.
- Choosing an unsuitable structure: Then it becomes necessary to modify or replace it after installation.
- Savings in protection: The inverter is prone to malfunctions that cost more than the protection itself.
- Ignore future expansion: You will have to completely replace the inverter when adding panels.
Frequently Asked Questions
Are batteries necessary in every solar system?
No. If network coverage is available and your goal is to reduce your bill, a battery-free system is usually sufficient. Batteries are necessary for locations far from the network or for those who want to operate the system during outages.
Does the cost per kilowatt decrease as the system gets larger?
Generally, yes, because factors like design, mobility, and operation don't multiply with size. But size should be based on actual consumption, not just on reducing the cost per kilowatt.
Is an aluminum structure more expensive than a galvanized iron structure?
It varies depending on the design and quantities. Aluminum is lighter and corrosion-resistant, and hot-dip galvanized iron is durable and suitable for most projects; the choice depends on the surface, loads, and environment.
Why does the contractor request a site visit before finalizing the price?
Because the type and height of the roof, shading, cable spacing, and electrical panel location all affect the design and quantities, the price based on photos alone may change after inspection.
Is it possible to start with a small system and then expand it?
Yes, provided that it is planned from the beginning: an inverter that accepts additional panels or the possibility of adding a second inverter, a reserved space on the roof, and an expandable structure.
Do you want a clear price quote with detailed specifications? MITS GROUP designs tethered, hybrid, and detached solar power systems, manufactures galvanized mounting structures at its factory in Al-Kharj, and provides feasibility studies showing expected output before you make a decision. Start by estimating the size using our solar energy calculator, then send us your invoice.
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