The BIG one…. How do I compare value for money between different battery systems?
Key points –
- Understand why you want a battery system – this should inform you what specification you actually need, i.e. size, discharge rate, islanded or not etc.
- Once you know your requirements for all eventualities go ahead and choose two brands that are as close to each other as possible that still both meet your already listed needs. It is quite likely that they will not match each other exactly in performance, useable storage capacity, installation location, costs or even warranty. Finding two identical items might be challenging.
- Make sure you are comparing like for like as much as you can – if not decide what it most important to you. Can you live without a certain specification or not? Are there any red lines that must not be crossed – you might either have to be flexible or actually go for a higher specification battery than you initially thought.
- Have no pre-conceived ideas – cost is no indicator of value for money. Depending on what is most important to you there may be surprising solutions.
First you must decide what you want it for i.e. maximising self-use of solar or running you through the night all the way through to a full emergency power supply for the whole home e.g. islanding from the grid with enough capacity for a full day. This will tell you the size you want and the discharge rate you need.
Realistically you probably have a budget you wish to stay within. This is perfectly reasonable and having already learnt that not all systems are equivalent in practise e.g. discharge rates etc you must be clear about what you are comparing. In other words, you must be clear about specifications when comparing two systems as even though one may appear to offer less value for money at first glance e.g. be more expensive, it may be more practical in the delivery of its purpose. As such the cost in £££ per kWh storage accessible may be better than something that appears better initially due to a lower price. This is the old rule that cheap does not necessarily mean value for money, It MIGHT but not necessarily.
Remember to compare:
Useable capacity – Rate of discharge – Enclosure rating – Operating temperature – Warranty.
This will help you to decide…
Written by John Rowlatt