Can too much solar for a home be possible?

Everyone yells from the rooftops install more solar, embrace the sun. But where is the line where it becomes too much solar? Thats what we tried to figure out.

We're looking into solar system sizing this week.

Which is based on one question... Is there such a thing as too much solar for a home? Probably, but where is that line?

I'm using my mum's energy and home as an example of how much solar would be too much solar for her.

A 100% increase in her solar size increases her solar consumption by 12%

A few weeks ago, a solar/battery company told me the analysis SolvingZero provides homeowners is too close to the truth, and many installers will hate it because they won't be able to oversell unsuspecting homeowners with oversized solar systems.

I showed this company my mum's SolvingZero dashboard, where she viewed three different solar system modelled sizes for her home: a 7.6kW, 10.4kW, and 14.8kW system.

In her dashboard, she can see that the increase in solar capacity from 7.6 to 14.8kW only equals a 12% average gain in the amount of solar energy she consumes.

These numbers are based on the energy consumption patterns of my mums house which I can access from her smart met

er when she uses the SolvingZero app. In the app we forecasted how different solar sizes would impact her energy consumption patterns.

If you'd like to try this for your home, I have more details about how to get your own free dashboard at the end of the article.

The graph below shows a full year of solar energy consumption for the three solar system sizes.

My mum's consumption of solar energy would increase by around 6 to 20%, depending on the month, which averages to the 12% mentioned earlier.

One quick context note, in the SolvingZero tool I can choose which direction the panels are facing. The 7.6 and 10.4kW sized systems are split to face 60% north and 40% west, and the 14.8kW sized system has around 15% facing east.

Her solar energy exports would increase, but she will consistently hit the export limits

The amount of energy my mum would export back into the grid at the 14.8kW system size would be substantial. From the 7.6kW to the 14.8kW system, her exports would increase by around 105% to 168%, depending on the month.

The graph below shows the energy my mum would export back to the grid for the feed-in-tariff credits, given the different-sized solar systems.

Unfortunately, in my mum's area of Melbourne, there is a 5kW export limit, which she would consistently hit given the larger system, even with trying to split the system to the west, north, and east to spread the energy production throughout the day.

The amount of energy she could export into the grid on a 14.8kW system would be much lower than indicated in the above graph, limiting her actual export value.

There will also be a decrease in the feed-in-tariff credit value in the future. As solar becomes more prolific, these credits will continue to decrease in value for most Australians. Any current benefit of exporting more energy should be considered when intentionally oversizing.

Use the savings to invest into other parts of the home

I am not advocating for undersized solar systems but more for a considered approach to purchasing our solar systems.

Some homeowners out there need to step back and assess their options and would be better off investing part of their cash into other parts of the home. If 400-watt solar panels cost $250 each, and my mum chooses the 7.6kW system instead of the 14.8kW, that is a savings of 18 panels, which equals $4500.

That's enough to buy a high-efficiency heat pump for her hot water or to insulate her ceiling. Upgrading parts of the home and buying solar panels will pack a more profitable one-two punch than purchasing an oversized solar system and hoping for the best.

Naturally bigger families will need a bigger system, so do a deep dive into your own consumption

My mum uses around 16kWh of energy daily, which is bang on the Australian average. But she is one person on her own. A family of four or five naturally uses more energy and needs a larger solar system.

It could well be possible that filling up a whole roof with solar is the best option for a big family. But rather than guessing it's better to make informed decisions based on your actual energy usage, and I'm not just talking about looking at one or two energy bills and calling it a day.

The size of the solar system should depend on the usage patterns of the home and the future plans for upgrading the home. There has to be a deep understanding of how the home uses its energy every hour of the day and every month of the year to get a full picture of what the house needs.

The size of the solar system should be relative to the needs and wants of the home, rather than a random sizing that an installer says is right.

Access your energy consumption data to figure out what is best for your home

If you have a smart meter and want to use your energy consumption data to see how different-sized solar systems on your roof would affect your bills and your dependency on grid energy, then we can help you do this for free.

We can read the data of any smart meter in Australia without visiting the home or connecting a device. We then use eight years of historical weather data near your home to forecast how different solar systems will reduce your energy bills and reliance on grid energy.

If you'd like to try it out, then let me know. Reply to this email, and we can get you set up.

Otherwise, you might be able to contact your energy distributor or energy provider and ask for your energy data to be emailed. From there, with a bit of work, you too can forecast what kind of system you will need for your home and make those key informed decisions.

This is the beginning of a comprehensive solar analysis

This solar analysis is only the beginning of what a home needs to consider when thinking about installing solar. If you'd like me to look into more solar-related questions like pricing, installation, payback, etc. Then let me know!