Unify Stock in Physical Store and Online: Why Your ERP Is Failing (and Shopify POS Is the Solution You Didn't Know Existed)

It's Saturday afternoon. A customer visits your website, sees that there are some size 38 sneakers left in the store on Serrano Street, and buys them for pickup (Click & Collect).

Half an hour later, she receives a cancellation email: "Sorry, we're out of stock."

What happened? Those shoes were sold in-store on Friday afternoon, but your PrestaShop and physical store's POS system only sync stock once a day (or worse, every 4 hours). That gap is where customer loyalty and your reputation die.

If you're a Retail Director at a brand with physical stores, you know that true omnichannel retailing in Spain remains a myth for 90% of businesses. Today, I'll explain how Shopify POS (Point of Sale) makes real what your ERP has been promising for years without delivering.

The problem of "phantom" stock in legacy systems

Most Spanish brands have this Frankenstein architecture:

• An older ERP system (Navision, SAP B1, Sage) as the "master".
• A POS software in stores (TPVsol, ICG, etc.).
• A PrestaShop/Magento for online shopping.
• A "middleware" or connector that tries to get everyone to talk to each other.

The problem is latency. Between the cashier scanning the item, the POS system notifying the ERP, and the ERP system notifying the website, minutes or even hours can pass. During sales or Black Friday, those minutes are critical.

Shopify POS: The "One Truth" About Inventory

The magic of Shopify Plus when you also use its POS (Point of Sale) system in your physical stores is that it eliminates synchronization . There's no need to "sync" anything anymore because the physical store and the website read the same database in the cloud.

Immediate operational advantages:

• 100% Real Stock: If you sell a shirt in the Barcelona store, it disappears from the website in 0.5 seconds. Literally.
• Endless Aisle: If a customer comes to your store and can't find their size, the salesperson can use the iPad (Shopify POS) to order it from the central warehouse stock and ship it to their home. You save the sale.
• Cross-Returns: Buy online and return in-store without any administrative hassles. The system handles it natively.

Turn your employees into digital ambassadors

In the old model, store staff hate the web because they feel it "competes" with them or gives them extra work (preparing Click & Collect orders) without attribution.

With Shopify POS Plus, you can attribute online sales to specific employees. If a sales associate helps a customer complete a web purchase using the store's iPad, they earn a commission. Suddenly, the web is their ally, not their enemy.

Do I have to throw away my code readers?

Not necessarily, but you'll want to. Shopify's hardware (or compatible hardware, like Star Micronics/Zebra) is modern, Bluetooth-enabled, and aesthetically pleasing.

Forget about back-office servers and VPNs that keep going down. Shopify POS works on iPads or Android tablets with a 4G/WiFi connection. If the power goes out in your store, you can continue accepting payments with a mobile payment terminal and an iPad with 4G. It's completely resilient.

Frequently Asked Questions about Retail and Shopify POS

Does Shopify POS work in Spain under the anti-fraud law (TicketBAI/Verifactu)?

Shopify is continuously adapting its system to local regulations. For very specific tax requirements in Spain (such as TicketBAI in the Basque Country), there are certified integrations or apps that connect Shopify POS with the necessary tax software to issue legal invoices that fully comply with regulations.

Can I continue using my ERP for accounting?

Yes, it's ideal. Shopify POS manages sales and operational inventory quickly. At the end of the day (or in real time), Shopify transfers all financial sales to your ERP (SAP, Business Central) for official accounting. This gives you the best of both worlds: agility in store and financial accuracy.

How much does Shopify POS Pro cost?

If you have Shopify Plus , the Shopify POS Pro license (which includes all the advanced staff and inventory management features) is free for up to 20 locations (stores) . This represents a huge saving compared to paying for traditional POS software licenses per register.