"Your electrics, safe in our hands"
1 What battery technology does the system use?
2. Why are you recommending it for me? Advantages/disadvantages can include charge/discharge efficiency, weight, size, life expectancy, safety considerations etc.
3 Are there any special considerations in terms of battery management / maintenance or storage location I need to be aware of? For example, due to their weight, some types of battery should only be located on the ground floor. Some will need ventilation as well.
4 Does the system require replacement of my existing solar inverter? [if you have one]
5 Will the batteries need mains electricity to charge at any time? Ask for an estimate of annual demand and cost. And, if applicable, whether the system can be programmed to charge from cheaper offpeak electricity.
6 What is the predicted lifetime of the batteries? How is this calculated? How many charge-discharge cycles? How many years?
7 How will I know that the batteries are nearing the end of their life?
8 What guarantees apply to the system/the batteries?
9 How would I safely dispose of used batteries at the end of their life?
10 What’s the cost of replacement/additional batteries? The batteries are likely to need replacing at least once in the lifetime of the solar panels.
11 Can I buy replacement batteries from anywhere or do I have to buy a special type from the original system manufacturer? You may be able to get better value batteries if you have more options and can shop around.
12 What is the useable storage capacity in kilo-watt hours (kWh)? The useable storage capacity is not the same as nominal capacity because most types of battery should not be 100% discharged as this shortens their life. If the figure is quoted as Amp-hours (Ah), what’s the voltage? Ah x V = kWh. 500Ah at 12V sounds better than 200Ah at 48V, when it is actually smaller (500 x 12 = 6kWh; 200 x 48 = 9.6kWh)
13 What does this mean in practical terms? Your installer should be able to indicate what type of appliances could be operated and for how long. For example a 3kWh battery operated with an allowable depth of discharge of 80% outputs 2.4kWh (80% of 3kWh) – enough to supply 200W of lighting for approximately 12hrs.
14 What is the charge-discharge efficiency? All battery systems lose some energy in the charge-discharge cycle but some technologies lose less than others.
15 Can I add more batteries at a later date to increase the storage capacity? 16 Will the system give me power during a mains power-cut? Some systems, such as those integrated or connected to a solar inverter, will not operate during a power-cut
17 If the system does provide power during a power cut, how will this work in practice (will I have to re-wire the house to achieve this)? And what will I be able to run?
18 Will the system affect my generation meter reading/FIT income at all?
19 Does the system incorporate a means of monitoring electricity in and out? This could help you get the most from the system or identify if more batteries would benefit you (assuming the system can be expanded).
20 Do I need to get any permissions/notify anyone before having a battery storage system installed? For example, your Distribution Network Operator will require notification of the battery storage system install. Others such as Ofgem and the local council may require notification.