Can I have my solar with batteries, and grid connect too?
When it comes to home electricity, the majority of consumers don’t understand it, and would rather not as it's dangerous and sounds complicated- it can be both of these. We then add a renewable energy system to the mix, we have even more confusion and less consumers who are actually interested in understanding how it works. Most consumers expect to pay someone else to install or advise the correct system that will work for the customer. The problem we have here, is that most consumers don’t understand, so they cannot communicate what the best solution for your situation will be, and most renewable energy sales consultants just want to get another sale. They will sell you the system that they make the most out of, or, failing that, a system they think you can afford. Now, in saying this, I know there are honest humans out there that do care for their customers and want the best system for the customer. At the end of the day, if you (the customer) have an understanding, and can communicate what you want, you will end up with a better outcome.
Can you have a battery bank and still be connected to the grid system? The short answer is yes, and technically no, at the same time. Let me explain.
Installing batteries to your solar system if you haven’t planned for it will most likely require rewiring of your solar panels. The reason for this is, if you have had a system installed that feeds the dinosaur, your panels are normally wired in series which gives your system high DC Volts to put into the grid system. Batteries require lower voltages, so your panels are normally wired in parallel, so that it increases the amps per hour not the volts. This is the reason it is important to plan your system and educate yourself. The majority of sales reps and installers have only had experience with grid connect systems, so they will tell you the way they have been trained. If they do not have a technical background or an understanding of electrical engineering systems, they will tell you this can’t be done because my boss says it can't.
So you have now had your panels rewired, and now we are going to install some batteries? No, wrong answer. The next thing to get the best performance out of your solar panels is to install an MPPT or a solar charge controller. In short, they protect your batteries and give you better performance. Once these are installed they will feed power into your batteries. Yay, you can now install batteries. Don’t get too excited, as you can’t use that stored power just yet.
The next part of your system is your inverter. If you already have a grid feed system, then it is likely that your inverter will not work with batteries. Now you go off to the shop to buy another inverter that works with your batteries and allows you to connect to the grid. More than likely, the guy at the shop is going to tell you this cannot be done!
What you want is an inverter charger for a DC system which you will most likely only find from solar guys that have been in the industry for a very long time, and who build off grid systems. This will allow you to now use your battery storage in your home!
There are a few different ways of having the final parts of your system wired back to the grid. Most of the time, a simple switch that senses a low voltage in your batteries will switch your home back to grid power while your batteries get charged back up from the grid (or your renewable energy supplies- in this example we will use solar).
If your system is sized correctly to your load and requirements, the only time your system will switch back to grid power is when you have had a few days in a row of low renewable energy production, or maybe you have had a house full of unexpected guests resulting in more daily consumption.
Having batteries installed can allow you to do lots of tricky things with your energy consumption, for example, if you wanted to, you could size your batteries to be large enough to run your lights at night, one power point that you watch your TV with, and maybe your computer. In most households, you can get away with a simple set up like that. The more users, and the more consumption you want at night, the more battery storage you will require, as well as a potentially more complex set up.
The point is, plan your system. If you haven't got a system yet, plan for battery storage now as a part of your system design. If you already have a dinosaur feeding system, it might require some more research and a complicated re jig of your system.
I hope this hasn’t scared too many people away or made it more complicated about batteries. It’s pretty simple at the end of the day, you have renewable energy system that puts power into the batteries of a day or night depending on your renewable source, and the excess that doesn’t go into the batteries should used that day. If your batteries are low, the system will switch your power consumption back over to the grid until your batteries are charged and ready to go again, simple!
Solar Battery storage is something that is, and will be, a part of most houses in the future when it comes to energy usage in the home.
Remember the best thing you can do is reduce your consumption and your load. The greenest energy is the type that you don’t have to make!