August Generation 2023

[Krill]

Dan, when you've posted the figures, it usally comes out that you can't beat the three batteries you have in the Teslas.

The cost of a battery system for your company should be considered in terms of business continuity if there is a power cut (ie what is the cost if there is a powercut and you cannot complete a days photo shoot?), and not in terms of arbitrage and shifting export (because business tariffs don't care at the moment). In that case, you need to look at the cost of a battery system that works in an islanded system and is large enough to manage one days work with teh full lighting kit.

I think in that case you would want to buy 4 or 5 batteries from Colin with ~12kW inverting power. Anything smaller doesn't actually manage the problem.

[dan_b]

Krill - you make a good point. Basically a UPS for the whole site. Different way to think about it. Hmm.

So what would that be, 4x Tesla Powerwalls with the full Islanding off-grid protection mode?

[Krill]

Essentially: Find out how often over the past few years you've had power cuts. If it's zero then there is essentially no business case IMO, unless there is concern the situation will be different in the future (ie this winter with reduced capacity etc).

Then work out how long you would need to be able to cover, and how large an inverter you need to meet peak demand. Personally, I would plan for a full days maximum use, plus 20%, and then as a plan B, look at what it took to just run the business critical parts of the business (ie the studio, tell everyone else to go home and work from there).

Then look at tariffs - a UPS needs to be charged at the start of the day to be useful, but also needs to be able to charge if the grid goes down. ie if the batteries are mostly empty in the morning when people turn up to work, then the grid goes down and the solar PV goes offline, the entire system is essentially a waste of money. So really you need a tariff that enables cheaper overnight charging and a higher export rate (Octopus Flux is truly awesome, but it's not available for business. Yet). If those tariffs don't exist, then you need a battery large enough to cover the entire night and then the day, or a battery you can control to not discharge overnight (ie use grid power from 1700 to 0800 etc).

IIRC you use 2kW as a baseline all night, and I have no idea why. Stuff that can't be turned off? If so, go back to the business case for a UPS to cover critical out of hours use as well, not just the day use.

It could be that one lost day costs the business £20,000 and you can cover this eventuality with £20,000 worth of equipment. I wouldn't know.

4 powerwalls would probably be enough though. That's 50kWh.

[JR]

2.5 system 10ZNShine panels Sunny Boy Inverter Orientation 170 degrees south Inclination 30 degrees East Mids.

August 2023 - 247

Worst generation August 2021 - 228
Best generation August 2022 - 324

Expected generation - 260