Product Input: Help us shine a light on batteries

Hi everyone,

I’m Kit and I work in Bulb’s Innovation Team. :battery: :sunny:

Here at Bulb, we know there are key challenges to overcome if we’re going to get to net zero by 2050. One of those challenges is ensuring a predictable supply of energy on a grid that is increasingly powered by renewables. We believe that batteries have a major role to play, charging up when there’s plenty of wind and sun and powering our homes when there isn’t.

I’m keen to understand whether there are things Bulb could be doing to help members install batteries in their homes. I’d love to hear from you if you already own a battery, or if you’re thinking about installing one. I’m especially interested in:

  • What motivated you to get a battery
  • The benefits that a battery can bring
  • What the perfect battery package would look like

I’m interested to hear all views, so don’t be shy! Even if you only briefly considered a battery for your home.

Sign up to be the first to hear about battery products / services from Bulb.

Many thanks!
Kit :battery:


Hi, Batteries are a must if you have a large array. I have Pylontech batteries and a Sofar controller with a capacity of 14.4kwh. During the months April - September I am almost off grid and during the other months I download cheap off peak power to use during the day and complemented by solar. There’s also the added benefit from having an EPS from the batteries during power cuts.


Hi, I’ve had solar since Jan 19 and already upgraded adding a 2nd array.

Initially, it was all about cost savings so that in retirement my pension will go on enjoyable things not utility bills. I also decided to consolidate energy use by changing to heat my hot water by electric not my oil boiler. I’ve also swapped to an electric car. Adding solar meant I needed to increase my Electricity use to justify adding solar. Increading my usage meant I needed to generate more energy. It’s a strategy not just a decision.

Going forwards I will want to replace my central heating and add a battery too.
From my experience, batteries are difficult to cost justify so the benefits are more about flexibility and convenience not cost savings. Longer term income should be possible from a battery as it’s cheaper for the grid to use virtual power stations than build new physical ones.

The problem as I see it is that the interface currently tends to lock battery customers into one virtual power plant solution. Ideally the interface needs to be compatible allowing customers to move between providers otherwise fair value might not be returned to customers.

Battery wise, my list if desires are an efficiency level which enables near zero grid use. This needs a fast responding system which can cater for a fluctuating grid.

I also need the ability to control a margin on the grid set point this allowing other smart devices to define priority subject to the margin of export set.

Data collection and an accurate and responsive real time interface is a must on mobile devices primarily, PCs 2nd. Data export and a great graphical interface. I’ve tested Victron, Puredrive and Lux inverter interfaces and all are lacking and don’t choose the best graphs. I’m an ex IT capacity and performance specialist so data presentation is important to me. Some systems are colourful but lack the numbers, others use bar charts when area charts would be better. Flexibility to alter the graph is important too. Graphs and data seem to be a weakness to batteries at present but they’re the only view if the battery a customer sees so very important imo.

I’m currently testing a battery for an installer and run a YouTube channel covering EVs , Solar and Home Batteries.

Another key requirement is a modular design allowing easy increases in capacity. Buying too big a battery wastes money as it’ll not cist justify buying too small makes you wish you’d bought more. Buying smaller then upgrading makes sense.

Capacity wise I’m looking for minimum 5kw but preferably 10kwh. Power wise , I’d like to be able to schedule a time boost of my immersion heater so need about 3.3 to 3.6kw minimum continuous power. To charge my EV faster a higher power output would be nice.

Timed charging with a soc limit is needed to take advantage of cheaper overnight Electric. Some form of interface to a varying tariff by hour of needed similar to Octopus Agile.

Control over SOC is important to protect the battery from degradation and the battery should be insulated enough to not go cold in a garage environment in order to prevent lower charging and discharge rates.

Power cut protection isn’t important to me as we rarely have a power cut for more than a few minutes.

I’m still torn between AC coupled and DC coupled as DC to DC charging avoids additional losses. Round trip efficiency is important as is the speed at which load increases are fully covered.

Hope my thoughts help and I’d love to be involved IF your battery solution is a good one.



1 Like

I am interested in buying a battery for the home but I am not sure that the economics work. During the summer my daily import is 3-5 kWh/day vs solar panel generation of 15-20 kWh/day, but this nets out at a cost to me of 15-20 p/day. So if a battery costs £2000 it would take 25-30 years to repay. This excludes winter usage.

If I signed up for the Bulb variable tariff and had a battery, during winter months when I am not generating much electricity could I charge the battery during low peak periods to use in higher tariff periods?

And also any thoughts about being able to sell battery stored electricity back to the grid/elect company?

@dovergs If you had a battery installed then you’d start to export energy to the grid once your solar panels had generated enough energy to fill the battery’s storage capacity. Conversely you’d only import from the grid once all the energy being stored in the battery had been used, more likely to happen over winter.

Part of the idea of batteries is to be able to charge them from cheaper off-peak energy, to then be able to use during peak rate periods, which would reduce your import costs and helps to balance demand on the grid

Thanks Matthew, I am aware of the way batteries work! I was wondering if Bulb would allow me to do what you suggest in the second part of your answer as that would make the battery much more economical?

Hi Jonathon,
What is your Youtube channel called?

@dovergs apologies, I didn’t want to assume knowledge. This will depend on whether you’re charging from the grid, or from your solar generation but @Kit_at_Bulb may have some more information on how flexible our batteries will be.

Helpful tip re your comment below, if you edit it to tag the community member you’re replying to but using @theirusername, then they’ll see your message sooner

Super interesting thread. Currently looking at solar install for my garden office (3.45 kWp) with option to go upto 6kWp through additional to the house. At that point my look at battery and hoping costs have come down to may the payoff quicker.

@jklondon it’s something we’re really excited to become involved in and see how it develops. The cost of battery storage for domestic use has already come down over this last year and with anticipated increases to electricity prices over the coming years, solar generation and storage will become even more valuable in real terms. I’d be interested to know what you’d consider a worthwhile payback time to invest in a battery

hi . i would consider a worthwhile payback time to invest in a battery, £300, a year, thus worth my time, and reduce my carbon footprint