If you’re interested in finding an innovative way to save on your household energy costs and future-proof your home against the rising tide of electricity prices, then this piece on home energy storage by Roy Izzat is worth a read.

This is the story of Roy Izzat, one of our regular car-buying department customers. While buying his BMW iX3, we couldn’t help but notice he had a very impressive-looking home energy set-up.

I had always assumed these were purely for taking advantage of solar energy, but I was intrigued when Roy explained he was using it to store low-cost nighttime energy, which the house then used through the peak time off the grid.

Roy kindly agreed to write a detailed blog post for us – over to Roy.

Home Energy Costs, Investing to Save by Roy Izatt

This is one now happily retired enthusiastic car and computer geek’s story of development, through a love of premium cars from ICE vehicles to now much-preferring EVs and on to an investment in managing lifestyle electricity total costs.

After a few years driving 4WD Discos associated with enjoyable volunteering in “SE 4×4 Response” activities (not so much altruistic as enjoying playing with my toys in a useful way), I moved on to my first EV in retirement, a Jaguar I-Pace. I was not as motivated to save the environment as I was to enjoy EVs’ much-enhanced driving experience.

 I must also admit that after a career that allowed me 60 years of driving experience, with the privilege of having a company-supplied vehicle every 2.5 years in the later years of progress from a Master Mariner’s (Oil and Gas Tankers) through shore management-related positions, I have driven more cars than I care to remember.

The iPace was replaced by an equally enjoyable BMW iX3. As I am now awaiting the handover of a much anticipated Genesis GV60, I have had a great incentive to consider all options in managing home costs, especially as I now have to finance my vehicles personally rather than as an employment benefit.

This led to the discovery of the “Octopus Intelligent Go” tariff (Other EV-suited tariffs are available), which requires their customers to have a regular EV charging requirement to qualify. (You can receive a credit of £50 on your new Octopus account by using Roy’s referral code here)

Some individual car models are acceptable, but not all, whereas if one of their favoured residential wall charger brands is installed (an Ohme Home Pro in my case), any EV model vehicle can be charged. This is due to the tariff system needing to schedule charging to suit the cheaper night rates, either through the charging unit or directly with compatible cars that have software accessible to integrate with Octopus’s Intelligent Go system.

Given then that all electricity units, whether for car charging, or other domestic needs such as washing machine, tumble dryer, slow cooker etc. can then be at the reduced rate during certain times (presently 11.30 pm to 05.30 am), there is a substantial saving to be made if you can shift any consumption from the daytime rate (29.5p/Kwh) to the nighttime rate of 7.5p/Kwh. Smart plugs can help with this, or most modern appliances may have timer settings to enable this.

This is available all through a base of the suitable Tariff and EV with associated charger.

The next step was considering electricity storage in now reasonably well-developed battery home energy storage installations.

The advantage is obvious – if you can take as much as your battery capacity allows at 7.5p/unit overnight for use later when the grid supply costs 29.5p/unit. An even more significant advantage would be if that supply could come “free” from Solar panels!

Of course, nothing of value is free, but may I suggest that return, for example, on savings in a bank, can be easily beaten (as long as there is no foreseeable short-term need) by investing in a system appropriate to your needs. As others more competent than me will tell you, the first question to answer is, “Does an EV purchase suit me?” as the EV is the base requirement to justify this suggested home power management type of system.

I considered solar panels first; however, having enjoyed such a system when living in Kent and commuting to London, I’m now retired to much cooler Fife. This solution is probably more suited to younger people than me, given the investment payback times that may be available!

Battery storage was considered next, and I decided to install a 9.5Kwh unit, which requires an inverter unit to charge the battery overnight at a cheap rate, supplying the AC household needs during the day or expensive grid supply times. The capital outlay for this installation was about £8,000

I want to recommend the following installers and suppliers for the quality of their products and services. Installer of the first Andersen A2, then the battery system and Ohme charger: EVi Renewables

Givenergy (nationwide) and Ohme EV supplied the equipment.

Whilst this solution is not accessible to everyone, my sole objective in writing this is to help lay out the options according to my experience. I have no links other than as an experienced user to any brands mentioned.

Having had three months’ experience with the system, I found that the electricity saving in our four bed 2017 built (reasonably modern standard of insulation) detached house averages out at about £100 a month while the 9.5Kwh. The battery would run out at about 6 pm or around evening mealtime. This means TV and any other evening electricity consumption goes up to 29.5p/unit until the cheap rate of 7.5p/unit commences at 11.30 pm to supply any further consumption, recharge the depleted battery and charge the EV if connected.

As a detail, the chosen inverter can supply the household at a maximum rate of 3Kw per hour so if you have an unusually high demand from connecting many high-consumption devices at the same time, the additional energy storage requirements will come from the regular grid supply at the applicable Tariff time price.

Given the above experience and an existing customer sale opportunity from my chosen home energy storage supplier, I decided to add an additional 9.5Kwh battery to my system, which now can supply just about all the household needs for electricity at an average consumption rate of 18Kwh per day at a cheap rate! The additional cost was about £4000.

Perhaps the lesson is to fully explore your needs and projected consumption and install the capacity you need first, with a marginal cost-saving.

My best estimate is that payback time is about nine years, but improving all the time as electricity will no doubt increase in price, particularly at peak times, which this system gives some protection against.

The best estimated lifetime of the batteries is about 15 – 20 years, with a warranty from this supplier of 10 years.

I hope this article helps with any decisions you feel you need to make on home energy storage. Feel free to reach out in the comments section below.

By Roy Izatt
last updated  04/12/2023

2017 built 4-bed detached house (well-insulated) – electricity costs compared

2017 built 4-bed detached house (well-insulated)	Electricity Only			Compare Totals
	Kw	Price/unit	Total Price
Octopus Var. Tariff to 25/8/23	Kw Consumption now	6,500	£0.27	£1,747.20
	Standing charge @60.02 p/day		£219.00	£1,966.20
	Average daily consumption Kw Including EV 3500m/yr	18.3
With Battery Storage(Intelligent)	Annual
	Kw Consumption now	6,500	£0.08	£487.50
	Standing charge @60.02 p/day		£219.00	£706.50
GivEnergy? Octopus data check estimated cost	Capital Cost installed Nov 23	£12,000.00		£12,000.00
	Estimated Annual saving	£1,260
	Payback years estimate	9.5
	Date of estimate	09/11/2023