M&E Contrax Resources

Solar Savings and Payback

Resource Highlights:

The biggest savings usually come from using solar electricity on site, not exporting it.

Batteries can improve payback by increasing self consumption, especially for evening heavy homes.

Payback depends on system design, roof suitability, tariffs, and how you use electricity.

How to Estimate Your Return

Solar panels can reduce your electricity bills from day one, but the amount you save and how quickly you see payback depends on a few key factors. The most important thing to understand is where savings come from.

Most people assume export payments are the main benefit. In reality, the biggest value usually comes from using your own generated electricity on site.

This guide explains how solar savings work, what affects payback, and how to estimate a realistic return for your home or business.

Where do solar savings come from?

Using solar electricity directly

When your panels generate electricity, your property uses that power automatically. Every unit you use from solar is a unit you do not need to buy from the grid.

This is usually the largest portion of savings for both domestic and commercial systems.

Battery storage

If you have a battery, it stores surplus solar electricity during the day and supplies it later. This increases self consumption, which often increases savings.

Batteries are particularly useful when:

most electricity usage is late afternoon and evening

you want more independence from the grid

you plan to add EV charging

Export payments

If you generate more than you use and your battery is full, surplus electricity can be exported to the grid. Some households and businesses receive payments through export tariffs such as SEG.

Export payments can improve overall return, but they are usually a secondary benefit compared with self consumption.

Ways to improve solar savings

Small changes can make a noticeable difference:

run appliances during daylight hours where possible

use timers for washing machines and dishwashers

schedule EV charging to match solar generation when practical

consider battery storage if evening usage is high

use monitoring to track performance and spot changes early

The goal is to increase self consumption, because that usually delivers the best value.

The biggest factors that affect payback

Your electricity usage pattern

Payback tends to be strongest when you use electricity during daylight hours. Examples include:

home working

families at home during the day

commercial sites operating in business hours

If usage is mostly evenings, battery storage can help shift solar value into those hours.

Roof direction, pitch and shading

Solar output is strongly influenced by roof layout.

south facing roofs often generate the most across the year

east and west facing roofs can still perform very well, especially for morning and evening usage

shading from trees and roof features can reduce output

Design decisions such as array placement and inverter choice can improve real world performance.

System size and design quality

A system should be sized around your usage, not just roof capacity. Oversizing can lead to higher exports and lower self consumption, unless you have a battery or large daytime demand.

Electricity prices and tariff structure

If grid electricity is expensive, solar savings can be higher because each unit you generate offsets more cost. Time of use tariffs can also affect the best battery strategy.

Maintenance and monitoring

Solar is low maintenance, but monitoring protects payback by catching problems early. A system that underperforms for months without anyone noticing can reduce savings.

How to estimate a realistic payback

A professional estimate should be based on:

your annual electricity usage and daily pattern

roof suitability and shading assessment

expected annual generation for the system size

likely self consumption with and without a battery

a sensible allowance for export where applicable

warranties and expected component lifespan

The key is realism. The best installer will explain assumptions clearly and show you how the numbers are built.

Frequently Asked Questions

It varies by property, system size and usage pattern. A tailored estimate from a survey will provide the most accurate guide for your situation.

Often, but not always. If your home already uses a lot of electricity during the day, you may get strong value from solar alone. Batteries help most when evening usage is high.

They can help, especially if your system exports a lot, but most savings come from using solar electricity on site first.