Can Solar Panels Power a Heat Pump?

Heat pumps need electricity to run, and, naturally, since electricity is a renewable source, this only begs the question, can a solar panel power a heat pump?

Solar panels can produce enough energy to power a heat pump for your home. Solar panels and heat pumps can work very well together and will decrease your overall electricity costs.

But, things are never as black and white, so continue reading below. I share with you more in-depth information and details about everything you need to know about this interesting topic.

How Much Power Does a Heat Pump Use?

To fully answer the question, we need to take a step-by-step approach and gather all the variables. The first question that needs answering is how much power do heat pumps use.

While heat pumps are well-known to be one of the most energy-efficient ways to heat a home, and indeed they will save you a lot of money, they still need electricity to run.

The actual amount of electricity a heat pump will need to work properly will vary on several different factors.

• The local climate and seasonality.
• The condition of the ductwork and insulation.
• The condition and size of the home.
• How the heat pump is used.
• And the type of heat pump.

Although each individual case will be very different, we can take a look at a few averages.

The operating costs of heat pumps are about $850 per year, on average. Air source heat pumps may consume between $650 and $1,300 per year, while ground-source heat pumps may cost between $500 and $1,000 per year.

In comparison, other means of heating a home may cost about $400 and $3,000 per year for heating alone.

Upon further analysis, we can see that these numbers coincide with the averages given by the U.S. Environmental Protection Agency (EPA), which states that a geothermal heat pump can save, on average, between $400 and $1,500 in electrical bills for heating and cooling in one year.

How Much Power Does a Solar Panel Generate?

Technically speaking, a solar panel can power virtually any appliance in your home. A solar panel can power your washing machine, refrigerator, oven, TV, and so much more. But most importantly, it can also power your heat pump.

However, matters are not as simple as just sticking a few solar panels on your roof. The amount of electricity a solar panel is expected to generate depends on three main factors.

• The size of the solar panel.
• The efficiency of the solar cells.
• The amount of sunlight in your area (peak sun hours).

Although the size of solar panels may vary somewhat, it has remained mostly unchanged for several decades now. The standard solar panel measures at 65″ by 39″ and it consists of 60 solar cells which work in tandem to generate electricity. A larger solar panel produces more electricity, and this size has been found to be the most practical so far.

The efficiency of solar panels has dramatically improved over the last several decades. Back in the 1950s, solar panels were able to convert about 6% of the solar energy to electricity, while today, in 2020, the efficiency of solar panels has gone up to 18.7%. (Some higher-end solar panels can push that percentage up to 25%.)

To find how much electricity a solar panel generates, you need to do a few things. 

Take a look at the label of the solar panel. On this label, you will see listed the nominal power that the solar panel will generate in perfect conditions.

With that being said, the average amount of sunlight is arguably the most important factor. Although you may have a total of 8 hours of sunshine during the day, this does not translate to 8 hours of peak sun hours, which can be closer to 3 or 4. In fact, the average peak sun hours in the U.S. is about 3 to 5. (However, these numbers may vary.)

As of 2020, the top residential solar panels generate between 285 and 360 watts.

A single solar panel rated at 300 W that receives 4 peak sun hours in one day will generate 300W x 4 PSH = 1,200W or 1.2 kW per day.

The average solar system size used in the U.S. is about 5kW. (Although 10kW and 15kW solar systems are becoming more popular as of lately.) A 5kW solar system will generate about 20kw on a standard day with 4 peak sun hours.

How Many Solar Panels Do I Need?

Each solar system is designed to meet the needs of the household. An in-depth assessment is always carried out by trained professionals, whose purpose is to make a proper assessment of how much electricity you will need. Naturally, this also takes into account the electricity requirements of a heat pump.

Another question I sometimes get asked is what happens if the solar panel is not able to meet the requirements of the heat pump.

Worry not. If your solar panel is not able to meet your energy needs, you will just have to use some extra energy from the grid to meet your demands.

The solar panels will still work and produce the electricity they normally do, and you will need to supplement the rest with electricity from the grid. This will result in higher energy consumption and, ultimately, a higher energy bill.

When considering the consumption of a heat pump, its coefficient of performance (COP) needs to be considered. 

The average COP of air-source heat pumps varies between 3.2 and 4.5, and the COP of ground-source heat pumps is between 4.2 and 5.2

An average home situated in a mild climate requires between 5,000 and 30,000 kW per year for heating alone.

So let’s consider an average of 15,000 kW for cooling and heating and 5,000 kW for a total of 15,000 kW per year.

We also have a standard 5kW solar panel system that produces 5,000 kW per year. After a quick calculation, we end up with 10,000 kW per year that will be used from the electrical grid. 

A 5kW solar system will require 17 solar panels, assuming they generate 300W each. In other words, to cover the costs of running the heating pump in our example, we will either need to find a way to lower the electrical consumption of the pump or use a 15kW solar system, which will consist of 51 solar panels. (This will amount to 895.05 sq feet of solar panels.)

Is It Worth to Power a Heat Pump With Solar Panels?

It is true, the combination of a solar panel system and a heat pump (be it air or ground-source) can provide adequate heating for your home while lowering your energy bills.

Although a solar panel system can work with an air-source heat pump, it synergizes best with a ground source heat pump. When one system is at its lowest efficiency yield, the other one is at its peak and vice versa. These two systems provide the best level of flexibility in terms of cooling and heating.

But this is where we are also presented with the inherent problem of the two systems. They usually work best and are needed most at different times. A solar panel system will produce the most energy and work best during the summer seasons and the day, while a heat pump may be most needed during the colder seasons and not always during the day.

So if you want to use the solar panel explicitly for powering a heat pump, you may run into some problems. 

However, the benefits of the two systems are still present.

One will provide direct heating while the other will generate electricity which can be used any way you seem fit.

The biggest, and only, downside to combining a solar panel system and a heat pump together is the price. Yes, the high installation costs are usually what will deter many homeowners. Often the high initial costs will make the potential pay off not really worth it.

In many cases, the best return on investment may be achieved by better insulating your home rather than modifying or upgrading your heating pump and solar system.

Certified energy advisors can make these assessments.

What Types of Solar-Assisted Heat Pump Systems Are There?

There are two main types of solar panel systems that are available today: (1) photovoltaic (PV) solar panel systems and (2) thermal solar panel systems.

These two should not be confused.

A solar PV system generates electricity by absorbing the energy from the sun.

The energy generated by the solar PV panel can improve the performance of a heat pump that works in a colder environment. Research in this field has proven that a solar-assisted heat pump has a higher coefficient of performance (COP) compared to a standard air-source heat pump.

On the other hand, a thermal solar panel uses the energy from the sun to directly heat water or air. Integrating a thermal solar panel with a heat pump is referred to as a solar-assisted heat pump system. The thermal solar panel acts as a source of heat that feeds the heat pump.

There exist hybrid models of a geothermal solar-assisted, and air-source solar assisted heat pump systems. These offer more versatility, and in certain cases, lower installation costs, but may be harder to maintain and operate.