Medical clinic CT scanner with batteries + solar…?

[shaun.taylor.vet]

Hi everyone

After some theoretical advice if possible.

I am a veterinary practitioner and independent small business owner (Bristol, UK). We run a small but busy vet clinic. I am conscious that our clinic uses a lot of electricity, with various items of equipment running 24/7 (our average daily usage is 30-40 kWh).

I am thinking about adding batteries, solar, and EV charger to our clinic, and moving to a “dual rate / economy 7 / EV-friendly” tariff, in order to reduce our high electricity bills, using a combination of solar and night-tariff battery charging.

Problem is: we are also planning to install a large CT imaging scanner. These are thirsty monsters, which generate high-power streams of x-ray radiation when in use. The one we are looking at has the following electrical specs:

Power range 80-140 kV
Maximum mA = 560mA
Maximum power = 56kW
3-phase 75kVA mains supply is a necessary requirement for this machine.

(Sorry I hope these figures make sense, they are lifted direct from the manufacturer book.)

I’m no electrician, but if an average CT scan might run for say 30 mins, I guess this could equate to an energy consumption of 28 kWh, at a power rate of 56kW, for those 30mins?

If we performed say 2 scans per day, this could mean a total clinic daily energy usage of 96 (40+28+28) kWh, with peak draw being around 66kW, when the CT scanner is running for 30mins (56kW) alongside the rest of the daily clinic requirements (say max 10kW when busy).

I appreciate this might be ambitious, but I’m wondering if solar panels and batteries could (partially or fully) support the CT scanner power requirements, and/or the remainder of the clinic’s electrical needs, during a live CT scan?

I appreciate I may need a LOT of PV panels and batteries, and then there may simply not be enough space to house this kind of capacity (our premises isn’t huge for a medical practice, similar in size to say a 5-6 bed house). I accept that “full” support from solar and battery is thus unlikely, but I’d be happy with “partial” cover, at least to try and reduce some of our daily electricity costs, plus the bonus of being protected against power cuts (a real headache when you are mid-CT scan).

I’m more worried about whether an invertor / battery setup could cope with a sudden demand for 55(+10) kW at the moment the CT scanner’s start button is pushed. Is there a maximum power draw rating for invertors/batteries without them overheating, or damaging other components of the array? Are there inverters that are compatible with 3-phase 75kVA supply, and suitable for handling these kinds of large sudden power demands?

Our CT suppliers think not, and have suggested maybe hardwiring the CT scanner directly to the 3-phase 75kVA supply, with its own UPS (ie bypassing the domestic battery/solar array entirely) and just using the array for the rest of the clinic.

It may also mean the batteries are drained in the first few hours of the morning, and then we run the rest of the day on daytime (expensive) tariff, so maybe not even cost effective, but I’m just keen to know if possible, or just too ambitious.

Sorry for the naive questions, any advice appreciated, thanks in advance.

Shaun T

 

[Andy™]

whatever you fit will help, but they will not be enough on their own

you'll use pretty much whatever you generate in real time so no point storing it since there won't be much leftover to store

 

[SPECIAL LOCATION]

Welcome to the forum Shaun....

I cannot give you any useful answers.. But it is an interesting question....

My gut feeling is your paragraph "Our CT suppliers think not, and have suggested maybe hardwiring the CT scanner directly to the 3-phase 75kVA supply, with its own UPS (ie bypassing the domestic battery/solar array entirely) and just using the array for the rest of the clinic." may be a key point?

We do have another Vet on the forum..
https://electricianforum.co.uk/members/apache.828/

But, again I have no idea if he has any CT scanner / Solar / Batteries at his practice up north?

So I, like you, will be interested to see other contributors replies..

Meanwhile I will have another

 

[binky]

You would need a small field of solar panels to power the CT. It is possible to do what you want with batteries charged from solar/ or off peak . You are probably better off with just charging batteries in off peak rates, and no solar for that. You are also probably better off keeping the CT as a separate issue, and possibly as a totally seperate electric supply, the way it pulls power doesn't really suite PV, and this allows it to be run off a different tariff to the rest of the practice.

The energy use of the practice will absorb just about everything a roof array can generate on the size of property you describe. Batteries are therefore probably a bit pointless, but it may well be worth installing hybrid inverters to allow battery fitment at a later date to the solar panels. The monitoring software that comes with inverters these days will tell you if that's a viable idea.

 

[Chrisbee]

Might it be worth considering spending all the budget on batteries without solar?
Arrange things so that the scanner doesn't pull power from the batteries.

40kWh of batteries would allow running the practice all day at the night time tariff.
Running the scanner would cost what it costs.

 

[UNG]

Welcome to the forum Shaun

While what you are proposing is not impossible in an ideal situation but it may be difficult to deliver within the constraints you have mentioned
A battery storage system or a UPS to run the CT scanner would be rather large and expensive and even just to do a controlled shut down I doubt it would be viable with the likely cost involved
I was on a course recently at Givenergy and their commercial battery storage solutions were impressive with some produced as a packaged solution built into a shipping container
Local to me is a veterinary practice that was purpose built a few years ago to Passivhaus standards which has a PV installation without battery storage and an MVHR system installed the last time I was talking to the vet who built it he reckoned the annual electricity bill was around £700 - £800, I'm not sure how much the solar produces annually but it does export to the grid during the summer
To gauge your useage accurately I suspect you would ideally need to monitor the half hourly useage over a number of days to identify any peaks or troughs in demand which would help is sizing the system to meet your needs