You’re preparing to put a solar energy system on your home’s roof, or maybe you already have solar panels up there, and you’re thinking of adding a battery backup system, too. This way you can really ‘stick it to the man’ – the utility companies that relentlessly demand energy payments from homeowners and businesses here in Northern Illinois or Southern Wisconsin. But, maybe, you shouldn’t spend your money quite yet.
For some who install a battery backup system with their solar energy system, the goal is to completely cut the cord from the malevolent utility company. Of course, along with total energy independence, they also assume to save more money. If they research the idea before they jump in, they’re liable to decide it’s not such a good idea after all.
A battery backup can help in a power outage. However, considering the cost (and we’ll get to that below), this only makes sense if you live in an area that has frequent power outages. Even then, there’s a far-more cost-effective alternative – a generator. A generator will make more noise. You also have to add gasoline. But it will cost dramatically less than a battery backup system tied into your solar energy system.
Others believe that, by adding a battery backup system, they’re taking the final step to eliminate their carbon footprint. Wrong again. Instead, since your solar energy system won’t contribute as many kilowatts of extra energy it produces to ‘the grid,’ the grid will have to make up that difference. The carbon is produced anyhow. This brings us back to the question of cost.
Without a battery backup tied into your solar energy system, you’re contributing more electricity to ‘the grid’ and receiving credits for that electricity. The difference is significant.
The cost of a battery backup system added to your solar energy system can add 25-percent to the cost of the overall system. This is because it’s not as simple as running some wires to a battery.
The battery backup system requires considerable additional electronics and engineering. It needs to balance loads to match demand at all times. It needs to be setup so the battery is never overloaded by house loads or overloaded by the solar energy system. And it needs to be setup so it won’t send electricity into ‘the grid’ when there is a power outage where it could kill a line worker trying to fix the problem with ‘the grid.’
The negative aspects of a battery backup system include the complexity of the system, increased maintenance requirements, increase costs and decreased credit savings. Here is a rough breakdown of the costs you can expect with and without a battery backup system:
When tied to ‘the grid’ and using a battery backup, you may spend $6 to $10 per watt. If you have a battery backup but you’re not tied to ‘the grid,’ expect to pay roughly $9 to $15 per watt. But, with a solar energy system that is tied to ‘the grid’ but doesn’t have a battery backup system, you’ll probably spend $4 to $6 per watt.