If you’re considering installing a 7 kW solar system on your property, there are likely to be several questions that you need to be answered so that you make an informed decision on whether or not it is the right system, for you.
For example, how much electricity it generates, and whether it is enough or even worth it to invest in a system of that size.
In this post, I have compiled answers to common questions that someone considering installing a 7kW system might have. Hopefully, this helps you make an informed decision.
Note: This post is only intended as a guide. Always contact a qualified solar system installer.
How Much Electricity Does a 7 kW Solar System Produce?
A 7 kW solar system supplies an estimated 28 – 35 kWh or between 28 -35 units of electricity per day depending on the weather conditions and the efficiency of the solar system.
This production assumes about 4-5 hours of sunshine per day. You can expect the system to supply peak power when it is cool and sunny.
In practice though, typical AC power production can be off by more than 10-15% of the rated DC power production because of the less than ideal weather and the fact that the solar panels are not always operating at their peak power.
Is it a Lot? Is It Enough to Run a House?
At a monthly electricity production of about 840 kWh, a 7 kW solar system can meet most if not all of the electricity needs of an average residential customer in the US.
According to the Energy Information Association (EIA), the average electricity consumption of a residential customer in the USA was about 886 kWh per month (95% of the electricity production of a 7 kW system).
Whether or not it produces enough electricity to run your house depends on several factors:
- How many hours of sunshine your location receives ( the estimate assumes 4-5 hours per year)
- Your residential electricity bill.
The Importance of Matching Supply and Demand
Last but not least, considering that peak production is during the day, aim to use as many household appliances with a heavy current draw during the day to use as much of the generated electricity for faster payback.
How to Check if It Can Meet Your Residential Electricity Needs
Compare your average residential electricity bill (kWh) to the estimated monthly production of the 7kWh of about 840 kWh.
This can give you an idea of whether or not the solar system is suitably sized to meet your entire household consumption bills or not.
What Appliances Can It Power?
The 7 kW solar system is ideally suited to supply power to a home, shed, or cabin and can power many household appliances in a house including but not limited to:
AC, fridge, microwave, water heater, selected power tools, lights, TV, and laptops. If the system has a battery backup option then the runtime on the battery depends on the combined power consumption of the connected appliances, battery state of charge, and battery capacity.
Batteries for a 7 kW Solar System
If it is a grid-tie solar system, there’ll be no battery backup option. For systems with a battery backup option, there are several Lithium battery bank options usually from 3kWh and higher depending on how much runtime you’d want to cater for in case of an outage.
Battery chemistry options include but are not limited to partial charge carbon-sealed AGM batteries and Lithium-ion batteries at 24V or 48V.
Battery Bank Size (Ah) and Number of Batteries
This depends on the battery bank chemistry, desired energy storage, and voltage 24V or 48V.
For example, a 3 kWh Lithium-ion battery at 24V will have an estimated capacity of 120Ah. You may also have other battery capacities such as 10 kWh, 20kWh.
At 48V, the estimated battery capacity is about 60Ah. These batteries are also available in a single package.
How Many Solar panels?
This depends on the power rating of the solar panels used. Examples of solar panel configurations include 21 x 345-watt solar panels, 19 x 400-watt solar panels, 18 x 400-watt solar panels, or 15 x 480-watt solar panels. These are just a few of the possible combinations of solar panels you can use.
Is a 7 kW Solar System Worth It?
This really depends on your situation and objective. in my opinion, without subsidies, it is not worth it.
At current prices, a 7 kW grid-tie solar system costs about USD 18,000. This system generates an estimated 858kWH per month or 10, 296 kWh annually.
Assuming a tarrif of 12 cents per kW, annual savings amount to USD 1,235 ( 12 cents per kWh x annual electricity production of 10,296kWh).
It will take about 14.5 years (solar system cost of USD 18,000 / annual savings of USD 1,235) to recoup your investment assuming there is no subsidy.
Is it worth waiting for that long? In my opinion, without a generous subsidy, no.
The electricity production of a 7kW system at about 6.5 kW is probably sufficient to meet the electricity requirements of the average American residence, based on data from the EIA.
Of course, whether or not it meets your residential requirements depends on several factors not least your electricity consumption.
Is it worth it? This depends, in my opinion, it is not worth it given the long payback period unless there is a generous subsidy.