RV, off-grid and 12V systems

Can a Harbor Freight Thunderbolt 100W Panel Go Straight to a Battery?

Published · By the SolarPanelX editors · Prices and specs as of that date, from the pages under Sources

Summary

The owner's manual says no. The manual for SKU 71049 tells buyers to use an appropriate charge controller, sold separately, whenever the panel is connected to a battery, and not to attach it to a battery or the grid without a proper regulator, inverter or charge controller. The $99.99 panel comes with one Anderson-style connector and two mounting stands.

Panel specifications from the manual

The manual rates the panel at 19 V, 5.3 A and 100 W, with an open-circuit voltage of 24.5 V, a short-circuit current of 5.7 A and 72 cells. The product page gives 41.1 × 22.6 × 1.3 in and 15 lb, and the warranty runs 90 days from purchase.

At 24.5 V, the open-circuit voltage is a little over twice a 12 V battery's, and it is the number to hold against a controller's input limit. For a fixed mount the panel uses the predrilled holes on its back, with brackets or a frame sold separately.

What the kit adds

The Thunderbolt 100 W kit (SKU 70735, $169.99) adds a 10 A PWM controller, two 12 V LED bulbs, an 8 ft battery cable, a 10 ft Anderson-style cable and four "Z" mounting brackets, for $70 more than the panel alone. Its controller auto-selects 12 V or 24 V, accepts up to 50 V, and has Sealed, Gel, Flooded and user charge settings, and the kit manual says "Use with 12 volt batteries only."

The separate 30 A controller (SKU 68738, $69.99) is for 12 V lead-acid or gel batteries and takes up to 360 W of input. Its maximum input voltage is "25V max." on the product page and 50 V in the manual.

Two ways of saying 500 Wh

The panel page says it "Produces an average of 31 Ah (500 Wh) per day." The kit page says "up to 500 Wh per day in full sunlight." The same 500 Wh is presented as an average on one page and a maximum on the other.

Shopping for one? Browse RV and off-grid solar panels →

Sources

  1. Harbor Freight — THUNDERBOLT SOLAR 100 Watt Monocrystalline Solar Panel (SKU 71049)
  2. Harbor Freight — Owner’s Manual 71049
  3. Harbor Freight — THUNDERBOLT SOLAR 100 Watt Monocrystalline Solar Panel Kit (SKU 70735)
  4. Harbor Freight — Owner’s Manual 70735
  5. Harbor Freight — THUNDERBOLT SOLAR 30 Amp Solar Charge Controller (SKU 68738)
  6. Harbor Freight — Owner’s Manual 68738

We have not tested these products. Specs, prices, stock and terms are as published on these pages on the date above and can change; check the manufacturer or retailer before you buy.

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