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The lights go out at dinner time and the fridge hums to a stop, which is when how much solar panels cost starts to matter: the answer depends on the size of the kit, not on one panel alone. A small maintainer kit with one panel and a controller sits at the low end, while a full off-grid kit with panels, batteries, an inverter and a controller sits at the high end, because the kit holds the whole system. This guide walks through the parts that set the cost, in the order you buy them.
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How much solar panels cost: the quick answer
The quick answer is that a panel on its own is the smallest part of the cost. The cost grows with the watts of the panels, the amp-hours of the batteries, the watts of the inverter, and the controller, cables and mounts that tie them together. A 30W SOLPERK kit (on Amazon) with a 12V panel and an MPPT controller maintains a 12V battery, a 100W Topsolar kit (on Amazon) with a 30A controller is a small off-grid start, and a 5KWH ExpertPower kit (on Amazon) with six 100W panels, four 12V 100Ah batteries and a 3000W inverter is a full off-grid system. The rest of this guide walks through each part in turn, so you can see where the cost sits.
Step 1: Start with the panels
Panels are priced by watts, so start there. The SOLPERK listing states a 30W panel with a cell efficiency of 30%, the Topsolar listing states a 100W panel with an efficiency of 19.5%, and the ExpertPower kit holds six 100W panels for 600W in total. More watts means more power from the same sun, so panel watts set the size of the whole kit. See the 60W vs 100W portable solar panel comparison for how the watts change the size.
Size and weight follow watts. The SOLPERK panel measures 12.0 by 8.0 by 1.0 inches, the Topsolar panel measures 45.6 by 20 by 1.37 inches and weighs 15.84 lbs in the bullets, while the spec table lists 15.21 pounds, so check the listing before you buy. The ExpertPower listing gives dimensions of 35.43 by 22.83 by 1.18 inches. Both the SOLPERK and Topsolar listings state wind pressure of 2400Pa and snow load of 5400Pa, and the SOLPERK panel is rated for up to 25 years.
| Kit | Panel watts | Controller | Inverter |
|---|---|---|---|
| SOLPERK 30W kit | 30W | MPPT | Not stated |
| Topsolar 100W kit | 100W | 30A PWM | Not stated |
| ExpertPower 5KWH kit | 600W | 40A MPPT | 3000W |
These are the three reference kits in this guide. The SOLPERK kit is a maintainer for a 12V battery, the Topsolar kit is a panel kit with a controller for a 12V or 24V system, and the ExpertPower kit is a full off-grid system with batteries and an inverter. See the 12V vs 24V solar panel guide for how the voltage changes the system.
Step 2: Add the battery
A battery is the second cost driver, and it is priced by amp-hours and by cycles. The ExpertPower kit holds four 12V 100Ah LiFePO4 batteries with a built-in Battery Management System, rated for 2500 to 7000 cycles with a 10 year life. The SOLPERK kit maintains 12V batteries, including LiFePO, Lithium Ion, AGM, SLA and GEL, and its MPPT controller cuts off reverse current at night to avoid battery drain.
Bigger batteries hold more energy, and the ExpertPower kit expands to four batteries in series at 48V 100Ah or in parallel at 12V 1000Ah. The kit also has a low-temperature cutoff that stops charging under 23°F (-5°C), and Bluetooth for tracking the battery level on a phone. A battery with more amp-hours and more cycles costs more, because it holds more energy for more years.
Step 3: Add the inverter and the controller
The inverter turns battery power into household AC, and the controller sits between the panels and the battery. The ExpertPower kit holds a 3000W pure sine wave inverter charger with a 60A charger that changes from shore power to battery power in 5ms, a 40A MPPT controller and a 30A DC-DC charger. The Topsolar kit holds a 30A PWM controller, and the SOLPERK kit holds an MPPT controller with three indicator lights: blue for the panel, red for charging and green for a full battery. See the best MPPT solar charge controllers for LiFePO4 batteries for controller options.
The controller also guards the battery. The SOLPERK controller guards against overcharge, over-discharge, short circuit and reverse polarity, and the Topsolar 30A controller guards against overcharge, over-voltage, discharge and short circuit, with reversed polarity protection. The ExpertPower listing states its 40A MPPT controller lifts power generation by over 20% compared with PWM. A licensed electrician should install any kit that connects to home wiring. See the solar charge controller size guide for how to match the controller to the panels.
Step 4: Add mounts, cables and the small parts
Mounts and cables are the last cost driver, and they grow with the size of the kit. The SOLPERK kit includes a 360° adjustable bracket for the panel, the Topsolar kit includes 4 Z mounting brackets and one pair of red and black solar cables, and the ExpertPower kit includes six sets of solar panel mounting brackets, one pair of 20ft 10AWG solar panel-controller cables and one pair of 6ft 8AWG controller-battery cables, plus a Y branch adapter. See the adjustable vs fixed solar panel mount guide for mount options, and the best 10 AWG solar panel wire guide for cable options.
Plan for growth when you buy mounts and cables. The Topsolar kit expands to 260W on a 12V system or 520W on a 24V system, so the mounts and cables should fit the larger size. The ExpertPower kit expands to four batteries, so the cables and controller should fit the larger bank.
Ways to keep the cost down
- Buy the smallest kit that covers the load: a 30W maintainer for a 12V battery, a 100W kit for a small off-grid start, a 5KWH kit for a full off-grid system.
- Match the controller to the panels: a 30A PWM controller for a 100W panel, a 40A MPPT controller for 600W of panels.
- Plan for expansion: the Topsolar kit expands to 260W on a 12V system or 520W on a 24V system, and the ExpertPower kit expands to four batteries.
- Check the listing figures before you buy: panel watts, battery amp-hours, inverter watts and controller amps.
FAQ: power away from the grid
How many watts of panels do I need?
It depends on the load. A 30W panel maintains a 12V battery, a 100W panel starts a small off-grid system, and six 100W panels make 600W for a 5KWH kit. Add up the watts of the loads first, then match the panels to them.
What does a charge controller do?
It sits between the panels and the battery and stops overcharge. The SOLPERK MPPT controller cuts off reverse current at night, and the Topsolar 30A PWM controller guards against overcharge, over-voltage, discharge and short circuit.
How long does a solar battery last?
The ExpertPower LiFePO4 battery is rated for 2500 to 7000 cycles with a 10 year life, and the SOLPERK panel is rated for up to 25 years. Cycles and years are the figures the listings state, so check the listing for the battery you buy.
Can I expand a solar kit later?
Yes, if the listing states it. The Topsolar kit expands to 260W on a 12V system or 520W on a 24V system, and the ExpertPower kit expands to four batteries in series at 48V 100Ah or in parallel at 12V 1000Ah.
Do I need an inverter?
You need one if the loads run on household AC. The ExpertPower kit includes a 3000W pure sine wave inverter charger with a 60A charger that changes from shore power to battery power in 5ms.
Related solar guides
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More picks: 12V vs 24V solar panel, 60W vs 100W portable solar panel, best MPPT solar charge controller for LiFePO4 batteries and solar charge controller size.
