Renewable energy storage and you.
This is a subject I could ramble on about for many many pages, so I will try to rein it in.
Battery systems are the foundation and MOST IMPORTANT and most expensive part of a competent and reliable battery based energy system. It is also the most misunderstood part and this is evident in the very bad practices that have taken hold of the South African off grid and hybrid solar industry.
Firstly, let me start by saying that my comments here are from first hand experience over many years with dozens of different batteries. My comments also happen to be common knowledge in other large off grid /hybrid energy markets all over the world, and for good reason.
What are these bad practices you ask? There are 2 major issues with the majority of battery storage installations we see.
- Phesudo deep cycle batteries and standby float life designed backup sealed batteries being used prolifically. These battery types ARE NOT suitable for daily cycling in a renewable energy system. That is not to say that these batteries are not suitable or other purposes, I speak specifically to their suitability for daily cycling service in renewable energy applications.
- Parallel battery banks are not suitable at all in daily cycling applications. It is a bad practice and has a detrimental effect on battery life and overall storage capacity. Two battery banks in parallel in SOME instances can be undertaken if no alternative is available and are managed (but only with FLA type batteries) with copper bus bars to ensure equal electrical resistance, and battery balances are used on each bank to assist the the equal charging and discharging of the battery system. We see some storage systems with up to 6 banks of batteries. This is a very bad practice and hurts the industry as a whole.
Properly built deep cycle batteries from tier-1 manufacturers come in varying sizes and voltages for this reason. There are both vented (i.e Flooded batteries) or sealed non venting types such as AGM (absorbent glass matt) to choose from, depending on the application. I will talk more about the different types of batteries and their pros and cons in another post.
So then, why do we see these two bad practices everywhere? Simple economics. The cheap pseudo deep cycle battery costs far less than a proper deep cycle battery made for the purpose. So how does this impact things?
- It makes the total cost of the energy system far lower making it more affordable to more people, so the company benefits from increased sales due to reduced upfront capital cost.
- There is far more profit for the supplier/installer in the cheap battery in multiple banks/sets than there is the larger true deep cycle battery in one bank/set.
It is that simple.
This is, however, both a disservice to the customer and the solar industry at large in South Africa. As these battery systems perform poorly and fail prematurely, it is solar energy that is deemed unviable rather than the poorly designed and spec’d energy system.
I have tried countless times to explain this concept to numerous solar installers/suppliers, but the prospect of loosing money in the short term to ensure that they have a business in the long term (i.e killing solar energy before it really takes hold) seems unacceptable to them.
Although a quality deep cycle battery sized correctly for your electrical loads may cost more initially, it will last at least 3 to 4 times longer and have more available energy (storage capacity) than the cheap battery in paralleled banks. To be clearer, even a good battery in multiple banks will perform poorly; it is just amplified when using cheap batteries.
In conclusion, money well spent the first time will serve you far better. A well designed energy storage system with the correct battery and storage capacity will serve you for a up to a decade. On the other hand, you would get 2 – 2.5 years and be very lucky to get 3 years out of the cheaper alternative.
My comments here may not make me very popular with some solar installers/suppliers or battery manufacturers/distributors, but these are the facts, and the customer should be informed of them.
My concern is the integrity and viability of the off grid and hybrid energy (i.e. battery based) market in South Africa. Best practices will ensure our industry prospers, which everyone will benefit from.
For more info on what batteries to avoid for daily cycling, or if you would like a more in depth explanation of this post, please email us
To see what we mean by proper deep cycle batteries, view our battery page here;