By generating clean electricity, solar power systems reduce the amount of coal and natural gas burned in power stations. This reduces the amount of pollutants and greenhouse gases released into the atmosphere, which contribute to disease and man-made climate change. Fossil fuels also require extraction processes such as fracking and surface coal mining, which have negative environmental impacts such as land degradation, water pollution and mine fires. The installation of solar power systems will obviously have a positive impact on the environment. But there are several different types of systems available, including those with batteries – how do they compare in terms of environmental aspects? and how to choose a solar power system for your projects?
Most existing solar systems are connected to the grid and do not have batteries
The electricity from the solar panels is first used by the equipment on site and any excess is exported to the grid for use by your neighbours. Any shortfall is provided by the grid and this setup is relatively cheap and efficient, using a simple inverter that relies on the stability of the grid. However, it is not very self-sufficient, as the inverter will shut down if a grid outage occurs. As the grid has minimal energy storage, the centralised power station reduces its output to compensate whenever your solar system is in operation. Each kilowatt hour of solar power reduces the power plant’s output accordingly. In fact, the benefits are even greater because the power station not only has to meet the needs of the end user, but also bears the losses incurred in the power lines, which can exceed 20% in remote areas. Some argue that because coal-fired power stations lack flexibility, they will consume coal at the same rate regardless of the amount of solar power generated, when in fact they respond quickly enough.
Battery grid-connected (hybrid)
There are various reasons for incorporating batteries into grid-connected solar power systems. Some of these systems are very self-sufficient as they can power your equipment during grid outages. With enough batteries and solar panels, importing from the grid may become a rare event. However, adding batteries will not increase your net impact on fossil fuel generation. Of course, you will import less from the grid at night, and on the other hand you will output less during the day. Batteries also incur losses when charging and discharging, so the house will consume slightly more power than it would without them.

Off-grid
With the price of batteries falling, many people are now considering disconnecting from the grid. This is certainly the most self-sufficient option, but its adoption will be limited by the cost. A complete off-grid system can cost around 20,000 USD for a typical household. From an environmental point of view, there are disadvantages to disconnecting from the grid. At current prices, it makes sense to install a relatively large number of solar panels to help power the house during cloudy winter weeks or during the rainy season. The excess power generated on sunny days will be wasted as the off-grid system cannot be exported to the grid. Off-grid homes often use diesel generators to get through the worst weeks, or to pay for extra consumption such as guests. This small amount of fossil fuel use should also be taken into account. Grid-connected solar panels are more environmentally friendly than off-grid solar panels where the grid is available.
Conclusion
A grid-connected solar system without batteries is a very environmentally friendly option because the excess solar energy is fed into the grid, reducing the damage caused by fossil fuels. Installing grid-connected batteries does not usually directly benefit the environment, but it does help develop economies of scale in battery manufacturing and installation, which will help in our long-term transition to a 100% renewable electricity system. In specific cases, batteries may have direct environmental benefits if they contribute to mega solar systems, avoid grid infrastructure construction or upgrades, or if they enable an environmentally beneficial off-grid lifestyle.