Best 10 Solar Panel Suppliers For Bulk Orders - A Complete List

Securing solar panel suppliers for bulk procurement requires a rigorous approach that goes far beyond comparing unit prices. Retail buyers and project developers face significant risks from production delays, inconsistent quality, and logistical bottlenecks that can derail entire infrastructure projects. Successful sourcing demands a deep understanding of supply chain stability, technical specifications, and cross-border compliance protocols.

This guide outlines the essential steps for evaluating reliability, from verifying factory audits and IEC certifications to utilizing escrow services for financial protection. We examine how specialized B2B platforms like Global Trade Plaza, Alibaba, and EximNext mitigate risks through verification badges and integrated logistics. Readers will learn to calculate total cost of ownership, navigate complex documentation requirements, and select suppliers with the financial resilience to handle large orders during market volatility.

Why Bulk Solar Procurement Requires Specialized Sourcing

Procuring solar panels for retail resale differs fundamentally from securing modules for large-scale infrastructure projects or wholesale distribution. Retail buyers typically focus on unit price and immediate availability, whereas bulk procurement demands a rigorous analysis of supply chain stability, production capacity, and logistical coordination. Energy distributors and project developers cannot afford production delays or inconsistent quality, as these factors directly impact project timelines and return on investment.

The operational differences are significant. A bulk order often involves multiple container loads, requiring precise coordination of manufacturing schedules with shipping windows. Specialized suppliers understand the nuances of industrial-grade packaging, freight consolidation, and the documentation required for cross-border compliance. They also possess the financial resilience to handle large orders without compromising on raw material quality, such as polysilicon or silver paste, which can fluctuate in price and availability. Sourcing from these specialized partners ensures that the supply chain remains stable even during global market volatility.

How to Assess Solar Panel Supplier Quality and Reliability

What criteria determine if a solar panel supplier is reliable for bulk orders?

Assessing a photovoltaic manufacturer requires moving beyond marketing claims and examining verifiable operational metrics. First, verify production capacity and factory audits. Reliable suppliers provide transparent access to their manufacturing facilities, demonstrating consistent output capabilities that match your order volume. Look for evidence of automated production lines, which reduce human error and ensure uniform cell efficiency across batches. Financial stability is equally critical, as it indicates the supplier's ability to secure raw materials and fulfill long-term contracts without interruption.

Second, examine their certification portfolio and technical documentation. A trustworthy supplier will readily provide IEC 61215 and IEC 61730 certifications, along with detailed product data sheets. In our work with verified exporters on Global Trade Plaza, we see that top-tier manufacturers maintain organized digital records of these documents, making verification swift and straightforward. Finally, evaluate their after-sales support structure. Bulk buyers need clear warranty terms and responsive technical support to handle potential field issues. Suppliers who invest in robust customer service teams and transparent claim processes are better positioned to sustain long-term partnerships.

Global Trade Plaza: Verified Solar Panel Suppliers for Global Trade

Global Trade Plaza operates as a specialized B2B marketplace that prioritizes verification and risk mitigation for high-value industrial purchases. Unlike general consumer platforms, this network focuses on connecting bulk buyers with vetted manufacturing facilities. The platform implements a rigorous vetting process that examines business licenses, export history, and production capabilities before granting verified exporter status. This filtering mechanism significantly reduces the time spent on due diligence, allowing procurement teams to focus on technical evaluation rather than basic legitimacy checks.

A key feature for solar procurement is the integration of escrow services. This financial safeguard ensures that funds are held by a neutral third party until the buyer confirms receipt and quality of the goods. This mechanism protects buyers from non-delivery or significant quality deviations, providing a layer of security essential for large capital expenditures. Furthermore, the platform facilitates direct communication channels between buyers and factory representatives, streamlining negotiations on technical specifications and delivery terms.

For businesses seeking a trusted environment for international trade, Global Trade Plaza provides a structured approach to supplier verification. The platform’s interface allows buyers to filter suppliers by specific certifications and production capacity, ensuring that the listed entities can handle the volume required for commercial or utility-scale projects. This focus on verified exporters creates a more reliable sourcing ecosystem for critical infrastructure components.

Understanding Photovoltaic Specifications for Bulk Buying

When sourcing solar panels in bulk, technical specifications dictate the long-term performance and financial return of the installation. Buyers must look beyond the standard wattage rating and examine several critical metrics that affect energy yield under real-world conditions. Efficiency ratings indicate how much sunlight the panel converts into electricity. Higher efficiency modules require less roof or ground space, which can reduce balance-of-system costs such as racking and labor, making them attractive for space-constrained commercial sites.

Another crucial metric is the degradation rate, which measures how quickly a panel loses its power output over time. Standard industry warranties often guarantee that panels will retain 80 to 90 percent of their original capacity after 25 years. However, the annual degradation rate varies by manufacturer and cell technology. Understanding this curve helps project financiers model accurate revenue streams for the lifespan of the asset. Panels with lower annual degradation rates provide more predictable long-term performance.

The temperature coefficient is also vital, particularly for installations in hot climates. Solar panels lose efficiency as they heat up. A lower temperature coefficient means the panel maintains better performance during peak sunlight hours when temperatures are highest. Buyers should request detailed data sheets that include this coefficient, typically expressed as a percentage per degree Celsius above 25 degrees. Additionally, checking for IEC 61215 and IEC 61730 certifications ensures the panels have undergone standardized testing for mechanical load, hail impact, and electrical safety. For a comprehensive understanding of the documentation required to validate these specs and facilitate smooth customs clearance, refer to our guide on documents needed for international trade. These technical details form the foundation of a resilient supply chain.

Alibaba: Connecting with High-Volume Solar Manufacturers

Alibaba remains the most comprehensive directory for connecting with high-volume solar manufacturers. The platform allows buyers to filter suppliers based on transaction history, years in business, and specific product categories. For bulk solar procurement, the most critical feature is the Trade Assurance program. This service protects payment orders placed and fulfilled on Alibaba.com, providing a layer of security that is essential when dealing with large capital outlays.

When sourcing through Alibaba, buyers must verify the supplier's manufacturing capability. Many listings are from trading companies rather than factories. To identify genuine manufacturers, look for suppliers who provide detailed factory photos, video tours, and specific certifications such as ISO 9001. The platform also facilitates communication through its built-in messaging system, allowing buyers to request sample specifications and negotiate terms directly. For a deeper understanding of why businesses rely on trusted B2B platforms for these transactions, you can read our guide on why businesses rely on our B2B platform.

Made-in-China: Sourcing Industrial-Grade Solar Modules

Made-in-China is a specialized platform that excels in connecting buyers with industrial-grade manufacturers. It is particularly useful for sourcing large-scale solar modules for utility-scale projects. The platform emphasizes factory audits and verified supplier credentials, which helps reduce the risk of engaging with unverified entities. Buyers can access detailed supplier profiles that include production capacity, quality control processes, and export history.

The platform's search functionality allows for precise filtering by product type, such as monocrystalline or polycrystalline panels, and by capacity. This precision is valuable for buyers who require specific technical specifications for their projects. Additionally, Made-in-China offers inspection services that can be arranged through the platform, providing an extra layer of verification before shipment. For information on the documentation required to facilitate smooth customs clearance when importing from such sources, refer to our complete guide on documents needed for international trade.

Global Sources: Curated Solar Suppliers for Quality Assurance

Global Sources positions itself as a premium channel for buyers who prioritize verification over volume. Unlike platforms that aggregate millions of listings, Global Sources curates a smaller base of suppliers, many of whom are established exporters with long histories in the photovoltaic industry. This curation reduces the noise, allowing procurement teams to focus on manufacturers that have already passed rigorous entry criteria.

In our work with verified exporters on Global Trade Plaza, we see that buyers often struggle to distinguish between trading companies and actual factories. Global Sources addresses this by requiring suppliers to undergo identity verification and factory audits before they can list high-value items like solar modules. The platform displays these verification badges prominently, giving buyers a clear signal of legitimacy without needing to conduct independent background checks immediately.

How does Global Sources ensure quality for solar panel suppliers?

Global Sources ensures quality through a multi-layered verification process that includes business license validation, on-site factory inspections, and performance tracking. Buyers can filter results to show only "Verified Suppliers," which indicates that a third-party inspection agency has confirmed the supplier's physical existence and operational capacity. This is particularly valuable for bulk orders where the risk of engaging with a shell company is high. The platform also facilitates face-to-face meetings through its offline trade shows, allowing buyers to inspect panel samples and discuss technical specifications in person before committing to large contracts.

The platform’s interface is designed for serious B2B transactions. It provides detailed company profiles that highlight export markets, production lines, and quality control certifications. For buyers concerned about compliance, these profiles often include links to ISO certifications and IEC test reports. This transparency helps in the initial screening phase, ensuring that only suppliers with the necessary infrastructure for bulk solar panel manufacturing are considered.

EximNext: Streamlining International Solar Trade Logistics

EximNext focuses on the operational complexities of international trade, particularly for buyers who lack in-house logistics expertise. Sourcing solar panels is only half the challenge; getting them to the project site without damage or customs delays is the other. EximNext integrates logistics solutions directly into the sourcing workflow, offering end-to-end support that covers freight forwarding, insurance, and documentation.

For bulk solar orders, logistics are critical because solar panels are fragile and bulky. Standard shipping methods can lead to broken cells or damaged frames if not handled correctly. EximNext provides access to specialized freight forwarders who understand the requirements for transporting photovoltaic modules. This includes advice on container loading patterns to minimize stress on the panels and recommendations for protective packaging that meets international shipping standards.

How does EximNext simplify logistics for bulk solar panel orders?

EximNext simplifies logistics by offering a unified platform where buyers can request quotes from multiple freight forwarders, track shipments in real-time, and manage documentation. The platform’s documentation support is particularly useful, as it helps generate the necessary bills of lading, commercial invoices, and packing lists required for customs clearance. This reduces the administrative burden on the buyer and minimizes the risk of errors that could lead to delays at the port.

Additionally, EximNext provides tools for managing payments and escrow services, ensuring that funds are released only when the goods are shipped as agreed. This financial security is crucial for bulk orders, where the transaction values are significant. By integrating logistics, documentation, and payment management, EximNext creates a streamlined process that allows buyers to focus on their core business rather than the intricacies of international trade.

For more insights on how to build a resilient supply chain, you can read our guide on why businesses rely on our B2B platform .

Total Cost of Ownership Beyond Unit Price

When negotiating bulk solar panel orders, focusing exclusively on the unit price per watt is a common strategic error that often leads to higher final costs. The total cost of ownership (TCO) for bulk solar panel imports encompasses a wide range of variables that extend far beyond the manufacturing invoice. In our work with verified exporters on Global Trade Plaza, we observe that buyers who neglect these secondary costs frequently face margin erosion due to unexpected freight spikes, insurance premiums, and customs duties.

The landed cost calculation must include several critical components:

• Freight and Logistics: Solar panels are bulky and fragile. Shipping costs vary significantly based on container type (e.g., flat rack vs. standard container), fuel surcharges, and port congestion fees. For large orders, securing consistent freight rates is as important as the product price.
• Insurance: Given the high value and fragility of photovoltaic modules, comprehensive marine insurance is non-negotiable. Premiums are calculated based on the total cargo value and the risk profile of the shipping route.
• Customs Duties and Taxes: Import tariffs vary by country and trade agreements. Some regions offer duty exemptions for renewable energy equipment, while others impose significant levies. Buyers must verify the current Harmonized System (HS) codes and applicable tariff rates before finalizing the order.
• Testing and Certification Fees: Certain markets require third-party laboratory testing upon arrival or prior to customs clearance. These costs, though sometimes overlooked, can add substantial amounts to the project budget.
• Delay Penalties: Supply chain disruptions can lead to demurrage charges at ports. Planning for buffer times in the logistics schedule helps mitigate these risks.

By analyzing the complete financial picture rather than just the sticker price, buyers can identify suppliers who offer better overall value through efficient logistics partnerships or favorable trade terms. This holistic approach ensures that the final installed cost of the solar system remains competitive.

Compliance and Documentation for Solar Imports

Importing solar panels in bulk requires meticulous attention to regulatory compliance and documentation. The complexity of international trade means that missing or incorrect paperwork can result in shipments being held at customs, incurring storage fees and delaying project timelines. Understanding the essential documents required for smooth solar panel shipments is critical for any procurement professional.

The core documentation package typically includes:

• Commercial Invoice: This document details the transaction value, payment terms, and description of goods. It serves as the primary basis for customs valuation and duty assessment.
• Packing List: A detailed breakdown of the contents of each package, including weights, dimensions, and quantities. Accurate packing lists are essential for logistics planning and customs inspection.
• Bill of Lading (B/L) or Air Waybill: These are title documents that evidence the contract of carriage. The B/L is particularly important for sea freight, as it allows the transfer of ownership of the goods.
• Certificate of Origin: This document certifies the country where the goods were manufactured. It is crucial for determining eligibility for preferential tariff rates under free trade agreements.
• Conformity Certificates: Solar panels must often meet specific technical and safety standards in the destination country. Certificates from accredited testing laboratories (such as IEC or UL standards) prove compliance with these regulations.
• Insurance Certificate: Proof of insurance coverage for the cargo during transit.

For a deeper understanding of the specific paperwork involved in cross-border transactions, you can refer to our complete guide on documents needed for international trade. This resource provides detailed templates and explanations for each document type.

Ensuring that all documentation is accurate and consistent across all forms is vital. Discrepancies between the commercial invoice and the packing list, for example, can trigger customs inspections and delays. Buyers should work closely with their freight forwarders and suppliers to verify that all documents align with local import regulations. This proactive approach minimizes the risk of administrative bottlenecks and ensures a smooth clearance process.

Logistics and Installation Planning for Large Orders

Moving hundreds or thousands of solar panels requires more than standard freight coordination. The physical nature of photovoltaic modules makes them highly susceptible to micro-cracks and edge damage during transit. A single compromised panel can reduce the efficiency of an entire string, leading to significant power losses. Therefore, distributors must plan logistics with a focus on handling integrity rather than just cost efficiency.

When coordinating with installation teams, it is essential to establish a clear chain of custody. Large orders often arrive in standard 40-foot high-cube containers, but the internal loading strategy determines the safety of the cargo. Panels should be palletized using reinforced cardboard or wooden bases that distribute weight evenly. Stacking height must be strictly controlled; exceeding manufacturer recommendations for pallet stacking can crush the bottom layers of modules. In our work with verified exporters on Global Trade Plaza, we see that buyers who specify "no stacking" for certain fragile high-wattage modules often pay a premium for more containers but save thousands in replacement costs and labor hours.

Best practices for container loading include:

• Pallet Configuration: Ensure pallets are shrink-wrapped tightly and corner-protected to prevent shifting during road transport.
• Load Planning: Use dunnage bags or airbags to fill void spaces in the container. This prevents lateral movement when the truck brakes or turns.
• Receiving Inspection: Coordinate with the site manager to perform a visual inspection immediately upon unloading. Document any visible damage with photos before signing the delivery receipt.
• Storage Conditions: If installation is delayed, panels must be stored in a dry, covered area. Moisture ingress into the junction box or backsheet can lead to long-term degradation.

Furthermore, synchronization between the logistics provider and the installation crew is critical. If panels arrive before the mounting structure is ready, they occupy valuable site space and risk theft or weather damage. Buyers should align the delivery schedule with the construction timeline to ensure a "just-in-time" arrival. This reduces on-site inventory management costs and minimizes the risk of damage from other construction activities.

After-Sales Support and Warranty Management

Procuring solar panels is a long-term investment, and the supplier's commitment to after-sales support is as important as the initial unit price. Unlike consumer electronics, solar modules have a 25-to-30-year operational lifespan. During this period, issues such as potential-induced degradation (PID), hot spots, or frame corrosion may arise. A reliable supplier must have a robust mechanism for handling warranty claims and technical disputes.

Warranty terms in bulk orders are typically divided into two categories: product warranty and performance warranty. The product warranty covers manufacturing defects, such as delamination or cell breakage, usually for 10 to 15 years. The performance warranty guarantees that the panel will produce a certain percentage of its rated power (e.g., 80% after 25 years). Buyers must ensure that these warranties are backed by the manufacturer, not just the trading company, and are transferable if the system is sold.

Key elements of effective after-sales support include:

• Spare Parts Availability: Suppliers should maintain a stock of spare modules, junction boxes, and connectors. In the event of a small batch failure, having immediate access to replacements prevents project delays.
• Technical Support Channels: Look for suppliers who offer dedicated engineering support. This includes assistance with system design validation and troubleshooting inverter compatibility issues.
• Claim Process Clarity: The contract should specify the documentation required for a warranty claim, such as serial number logs and photographic evidence. A streamlined process reduces administrative friction.

In our experience, suppliers listed on Global Trade Plaza often provide more transparent warranty structures because their reputation depends on long-term buyer satisfaction. When evaluating suppliers, ask for references from previous bulk buyers and inquire about their response time to technical queries. A supplier that responds quickly to pre-sales questions is likely to be more responsive when a warranty claim arises. Additionally, consider the geographical proximity of the supplier's service centers. If a major defect is identified, the cost of shipping defective panels back to an overseas factory can be prohibitive. Local or regional service centers can often perform initial assessments and replacements more efficiently.

Common Pitfalls in Bulk Solar Procurement

Even experienced procurement managers encounter specific challenges when scaling solar panel orders. Identifying these risks early allows for better contract structuring and risk mitigation. Below are the most frequent errors and how to avoid them.

Quality Inconsistencies Across Batches

Solar panels are manufactured in batches, and slight variations in cell efficiency or frame finish can occur. A common mistake is assuming that a sample unit represents the entire production run. To mitigate this, require the supplier to provide a production sample from the actual batch before final shipment. Include a clause in the contract that allows for random third-party inspections at the factory gate. This ensures that the panels meeting the contract specifications are the ones being loaded into containers.

Payment Fraud and Escrow Mismanagement

Attempting to pay large sums via direct wire transfer to unverified accounts is a significant financial risk. Many scams involve fake supplier identities or compromised bank details. Always use secure payment methods such as Letter of Credit (LC) or platform-managed escrow services. These tools hold funds until goods are shipped and documentation is verified. Never release the final payment tranche until you have received the Bill of Lading and inspection reports confirming the shipment details match the purchase order.

Supply Chain Bottlenecks and Logistics Delays

Solar panels are fragile and require careful handling. A frequent oversight is underestimating the complexity of freight forwarding for large volumes. Panels must be stacked in specific orientations to prevent micro-cracks during transit. Working with freight forwarders who specialize in renewable energy equipment is essential. Additionally, verify that the supplier has experience with Incoterms relevant to your logistics setup. For example, if you are using FOB (Free on Board), ensure the supplier handles export customs clearance efficiently to avoid port delays.

Ignoring Compliance and Certification Updates

Regulatory requirements for solar imports vary by country and change frequently. Relying on outdated certifications can lead to customs seizures. Ensure the supplier provides current UL, IEC, or CE certificates that match the specific model numbers being shipped. Cross-reference these documents with the latest import regulations in your destination country. For a detailed guide on the documentation required to clear customs, refer to our complete guide on documents needed for international trade.

Overlooking After-Sales Support Infrastructure

Many buyers focus heavily on unit price and neglect the supplier's ability to handle warranty claims. A supplier with low prices but no local service network can become a liability if defects arise years after installation. Verify the supplier's warranty claim process before signing. Ask for their average response time to technical queries and their policy on replacing defective units. Reliable suppliers will have a clear, documented process for handling claims, including provisions for shipping replacement parts or panels.

Conclusion: Building a Resilient Solar Supply Chain

Building a resilient solar supply chain requires a proactive approach to sourcing, verification, and logistics. It is not enough to find the lowest price; you must establish a partnership with suppliers who prioritize quality, transparency, and long-term support. By leveraging verified platforms like Global Trade Plaza, you gain access to a network of trusted exporters who understand the complexities of global solar trade.

Key Takeaways for Sustainable Sourcing

• Diversify Your Supplier Base: Do not rely on a single manufacturer. Establish relationships with multiple verified suppliers to mitigate the risk of production delays or quality issues.
• Prioritize Verification: Use platform-provided verification tools to assess supplier credentials, production capacity, and past performance. Look for suppliers with a history of positive feedback and successful bulk transactions.
• Invest in Documentation: Ensure all contracts include clear specifications, quality standards, and dispute resolution mechanisms. Proper documentation protects your interests and facilitates smoother customs clearance.
• Plan for Logistics Early: Coordinate with freight forwarders and logistics partners before finalizing orders. Understanding the shipping requirements for solar panels can prevent costly delays and damage.

By following these best practices, you can build a robust and reliable sourcing strategy that supports your business growth and ensures the successful delivery of high-quality solar panels. For more insights on why businesses trust our platform for verified reviews and supplier connections, read our article on why businesses rely on our B2B platform.

Frequently Asked Questions

How do I verify the quality of a solar panel supplier?

Verify quality by auditing production capacity, financial stability, and technical documentation rather than relying on marketing claims. Reliable suppliers provide transparent access to automated manufacturing lines that ensure uniform cell efficiency. Check for IEC 61215 and IEC 61730 certifications and detailed product data sheets. In our work with verified exporters on Global Trade Plaza, we see that top-tier manufacturers maintain organized digital records of these documents. This rigorous verification process ensures the supplier can handle bulk orders without compromising raw material quality or delivery timelines.

What are the key specifications to check when buying solar panels in bulk?

Check efficiency ratings, degradation rates, and temperature coefficients to ensure long-term performance and financial return. Efficiency ratings determine how much sunlight converts to electricity, reducing balance-of-system costs. Degradation rates indicate power loss over time, with standard warranties guaranteeing 80 to 90 percent capacity after 25 years. The temperature coefficient shows performance loss in heat, which is vital for hot climates. Request detailed data sheets for these metrics to model accurate revenue streams and ensure the panels meet mechanical and electrical safety standards.

How does Global Trade Plaza verify its solar panel suppliers?

Global Trade Plaza verifies suppliers by examining business licenses, export history, and production capabilities before granting verified exporter status. This rigorous vetting process filters out unverified entities, significantly reducing due diligence time for procurement teams. The platform integrates escrow services to protect funds until goods are received and inspected. This financial safeguard prevents losses from non-delivery or quality deviations. The interface also allows buyers to filter suppliers by specific certifications and capacity, ensuring listed entities can handle commercial or utility-scale project volumes.

What documentation is needed to import solar panels?

Importing solar panels requires IEC 61215 and IEC 61730 certifications along with detailed product data sheets for customs compliance. You must also secure commercial invoices, packing lists, and certificates of origin to validate the goods. For a comprehensive understanding of the documentation required to validate these specs and facilitate smooth customs clearance, refer to our guide on documents needed for international trade. These technical details form the foundation of a resilient supply chain and prevent delays at border crossings.

How can I avoid scams when sourcing solar panels from overseas?

Avoid scams by using platforms with escrow services and verifying supplier manufacturing capabilities through factory audits. Alibaba offers Trade Assurance to protect payment orders, while Global Sources requires identity verification and on-site inspections. Look for suppliers who provide detailed factory photos and video tours to distinguish genuine manufacturers from trading companies. Never release full payments upfront. Use these financial safeguards and verification badges to ensure you are dealing with legitimate entities capable of fulfilling large capital expenditure contracts.

What is the typical lead time for bulk solar panel orders?

Typical lead times for bulk solar panel orders range from 30 to 60 days, depending on production schedules and shipping coordination. Large orders often involve multiple container loads, requiring precise alignment of manufacturing with shipping windows. Specialized suppliers understand the nuances of industrial-grade packaging and freight consolidation to meet these tight timelines. Delays can occur if raw materials like polysilicon are scarce. Confirming production capacity and securing financial resilience with your supplier ensures the supply chain remains stable during global market volatility.

How do I calculate the total cost of importing solar panels?

Calculate total costs by adding unit prices, freight charges, insurance, and import duties to the base invoice amount. Solar panels are bulky and fragile, so specialized freight handling and protective packaging add to logistics expenses. Consider container loading patterns to minimize stress and damage during transit. EximNext integrates logistics solutions to cover these operational complexities, offering end-to-end support for freight forwarding and insurance. Accurate cost modeling must include these variable logistics fees to determine the true landed cost for your project.

What warranty terms should I expect from solar panel manufacturers?

Expect product warranties covering manufacturing defects and performance guarantees ensuring 80 to 90 percent capacity retention after 25 years. Manufacturers should offer clear warranty terms and responsive technical support to handle field issues. Evaluate their after-sales support structure to ensure they can sustain long-term partnerships. Suppliers who invest in robust customer service teams and transparent claim processes are better positioned to address potential failures. Always request detailed warranty documentation to understand the specific coverage limits and claim procedures.

Top 10 Solar Panel B2B Platforms

1. Alibaba

2. AliExpress

3. Global Trade Plaza

4. Made-in-China

5. Global Sources

6. DHgate

7. Amazon Business

8. EximNext

9. Faire

10. Kompass