Is a 3 kW Solar System Worth It? (+How Many Batteries and Solar Panels to Use)

Are you considering an alternative power source for your RV or cabin? Is it worth it?

A 2 kW solar system complete with an appropriately sized inverter can run many household appliances reliably.

You need to make sure that the solar system components – batteries, charge controller, inverter, and connected appliances are properly sized for the system to work well.

So in this guide, I discuss whether a 2 kW solar system is worth it, share some information to help you get started with selecting the right capacity of components – number and size of batteries, inverter rating.

I also give examples of appliances that you can connect to make the most of your 2 kW solar system investment without damaging it.

Is it Worthwhile Investing in a 2 kW Solar system?

If your objective is to save money, then investing in a 2kW solar system is not worth it from a financial savings standpoint unless there are subsidies available.

At the time of writing, a complete 2 kW solar system – solar panels, batteries, charge controller, inverter system costs about USD 3,000 plus installation.

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You are looking at a payback period of 7-10 years if there are no subsidies and at that point, you will likely have to invest in a replacement set of batteries.

Note: this assumes a tariff of 13 cents per kWh.

That said, solar systems are generally low maintenance compared to a generator, do not produce fumes, and are silent too with minimal running costs.

If these benefits are important to you and budget is not an issue then it is probably worth it.

How Many Batteries Can You Use for a 2 kW Solar System?

There are several possible battery setups you can use. Some examples are provided below:

AGM or GEL Batteries

2,400 Wh Battery Bank consisting of:

4pcs of 100 Ah batteries. You can connect them such that you have 2 strings connected in parallel of 2pcs of 12 AGM or gel batteries connected in series for a 24V bank.

Note: This harvests only about 30% of the generated energy of the solar panels estimated at 8 kWh.

You can use 200Ah batteries to store more of the 8kWh from the solar panels.

Lithium Batteries

3,600Wh battery bank consisting of:

6pcs of 50 Ah batteries. You can connect them such that you have 3 strings connected in parallel of 2pcs of 12V lithium batteries connected in series for a 24V bank.

Note: This harvests only about 50% of the generated energy of the solar panels estimated at 8 kWh.

You can use 100Ah batteries to store as much of the 8kWh from the solar panels.

Connecting the battery bank in a 24V configuration or higher enables you to use less thick cables that are easier to handle, are generally more affordable while lowering the system currents.

This can reduce the severity of damage in the event of a fault like a short-circuit as an example.

What Can a 2 kW Solar System Run?

A 2 kW solar system complete with battery bank and inverter can run several appliances from the lower power consumption appliances such as lights, TVs, laptops, low power tools, microwave, washing machine, coffee pot, air conditioner reliably provided:

  • The inverter’s continuous and surge power consumption is not exceeded.
  • The total daily energy consumption of the connected appliances does not exceed the energy generated and stored by the batteries.

Drawing more power from the inverter than it can handle results in an overload condition which usually shuts down the inverter and in extreme cases can damage it.

Here is an indicative list of appliances (with estimated runtimes that you expect from a 2 kW solar system). This assumes daily storage of about 2.4 kWh.

  • Lights: 10 watts, 9 pcs running for 5 hours = 10 x 9 x 5 = 450 watt hours
  • Tv: 50 watts, 1 pc running for 4 hours = 50 x 1 x 4 =200 watt hours
  • Laptop: 40 watts, 1 pc for 5 hours = 40 x 1 x 5 = 200 watt hours
  • Washing machine: 250 watts for 3 hours = 250 x 1 x 3 = 750 watt hours
  • Microwave: 800 watts for 1 hour (total) = 800 watt hours

Total = 2,400-watt hours total power consumption is 1,990 watts which can be handled by a 3,500 watt rated inverter.

Important to note that the combined surge rating should not exceed approximately 7,000 watts, the estimated surge rating of a 3,500 watt inverter.

Check your inverter’s owner manual for its surge rating.

How many panels to use in a 2 kW solar system?

You can have 10 pcs of 200 W ( 5 strings in parallel of 2 solar panels connected in series) or 195 W solar system or 20 pcs of 100 W solar panels ( ( 10 strings in parallel of 2 solar panels connected in series) for a 24V system.

Note: This is just an example, there are probably other configurations you can use.

Related questions

Can a 2 kW Solar System Run an AC?

Yes, it can run an AC provided its continuous and surge power rating does not exceed what the inverter can handle.

Make sure that the AC is rated for a 115V for it to work with the 110/115V inverter output.

Can a 2 kW Solar System Power a Whole house?

The estimated 8 kWh supplied by this 2 kW solar system is not enough to power the entire house going by the estimated daily energy consumption of an average house in the US, 2020 of about 30 kWh according to the United States Energy Information Administration (USEIA).

It can power some appliances but will likely not be enough for an average house.

It can ably power an RV, off-grid cabin or an outside shed, or any other setup whose daily energy demand is about 8 kWh.

Make sure you have enough batteries to store this much energy.

2 kW Solar system |How Much Electricity it Generates

Daily electricity output

A 2 kW solar system can generate an estimated 6 – 8 kWh ff energy per day assuming your location receives about 3-4 hours of sunshine.

Monthly electricity output

A 2 kW solar system can generate an estimated 180 – 240 kWh Of energy per day assuming your location receives about 3 – 4 hours of sunshine.

To get as much power as possible, the solar panels should be angled to face the sun as much for as many hours as possible with no shadows cast on the panels.

Clean the panels to remove any dust or other debris that can obstruct the sun from reaching the panels for maximum power output.

Final word

If you are looking to save money, you have access to the grid and there are no subsidies then from a financial savings standpoint, it is likely not worth it unless benefits use of clean, no noise pollution is important to you.

Should you decide to invest in one, while there are several possible battery bank configurations, you can consider, 2,400Wh battery bank made up of 4pcs of 100 Ah AGM batteries – 2 strings connected in parallel of 2pcs of 12V batteries or 6pcs of 50 Ah batteries – 3 strings connected in parallel of 2pcs of 12V lithium.

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