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"Gas Armageddon": Energy/electricity prices in EU/UK (and how to deal with them)

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james_s:

--- Quote from: tautech on August 26, 2022, 11:17:04 pm ---We have a solar powered data relay 'high site' installation with just three 300W panels in series for maintaining SLA's in a 24V series/parallel 4 battery installation of some 320Ahr capacity and my in just 2 1/2 years logging shows 1.5 MW of solar energy poked into the batteries......that's a lot of energy for free other than the initial investment.....ROI is entirely another matter as no other energy source was available at this remote location ~1km from the grid.

--- End quote ---

1.5 MWh sounds like a lot of power, but it's only around $150 worth of electricity in my region. Of course as you point out, in this application there are not a lot of viable alternatives, so you'd have to compare the cost vs running 1km of cable to the grid.

Someone:

--- Quote from: tom66 on August 26, 2022, 11:12:22 pm ---Surprised me that the benefits are still there.  It's really all down to the solar.  The off-peak is nice, but the solar is *great*.
--- End quote ---
Which makes the numbers a little misleading calling it a costing of a "battery", when its mostly just the costing of solar generation. If you want to separate out battery from solar, it should compare the cost/profit of a battery to selling solar power back into the grid (including regulatory/compliance costs etc) and/or a zero export inverter (dump excess production).

nctnico:

--- Quote from: tom66 on August 26, 2022, 11:12:22 pm ---Is a home battery and solar system worthwhile now?

--- End quote ---

The numbers look very optimistic. Try to work out how much total storage capacity the battery has and see if that covers your usage scenario. Last time I checked a Tesla powerwall is quite expensive per kWh stored (IIRC somewhere between 0.3 and 0.5 euro per kWh). The warranty of the Tesla powerwall is pretty clear on the total amount of energy it can store over it's useful life.

The Tesla powerwall has a total storage capacity of 37.8MWh with a capacity of 13.5kWh. Your proposed battery is smaller. With 12kWh a day you are at 4.6MWh per year. Extrapolating the Tesla numbers with your smaller battery gives a total storage capacity of 26.6MWh. So your battery will be worn after 5.8 years and costs about 10p per kWh.

Another issue I see is that the battery can deliver only about 4kW of power; that could be insufficient for an entire home.

tom66:
The GivEnergy batteries are limited to 3.6kW discharge, so it may struggle to keep up with cooking loads, but the majority of loads in the household are continuous, low power (fridge, computers, lighting etc.)  So I suppose if it doesn't keep up with cooking + microwave at the same time that's not ideal but not a disaster, it's grid-tie so it will cap at 3.6kW and remainder will come in as on peak energy.

Also 9.5kWh is the net capacity as the pack can be used to 100% DoD, but the sums actually still work quite well even with say 7kWh capacity. The saving is less, of course.  Interestingly though there's little benefit in going much beyond 12kWh.

The thing is, you don't need to cover your whole usage if you have solar: even on a winter's day, the array might add 1-2kWh to the pack, so a 9.5kWh pack can extend to 11.5kWh of effective usage.  The scenarios show on winter days there's some grid on-peak usage, but it's a tiny fraction of overall usage.

tautech:

--- Quote from: james_s on August 26, 2022, 11:43:15 pm ---
--- Quote from: tautech on August 26, 2022, 11:17:04 pm ---We have a solar powered data relay 'high site' installation with just three 300W panels in series for maintaining SLA's in a 24V series/parallel 4 battery installation of some 320Ahr capacity and my in just 2 1/2 years logging shows 1.5 MW of solar energy poked into the batteries......that's a lot of energy for free other than the initial investment.....ROI is entirely another matter as no other energy source was available at this remote location ~1km from the grid.

--- End quote ---

1.5 MWh sounds like a lot of power, but it's only around $150 worth of electricity in my region. Of course as you point out, in this application there are not a lot of viable alternatives, so you'd have to compare the cost vs running 1km of cable to the grid.

--- End quote ---
A little story if I may....
A school buddy and corporate accountant was tasked with improving a local general waste company's bottom line and as he was stationed in an office at their landfill, sealing, capping and capturing the methane for supplying 1 MW gensets was costed out in great detail and calculations for the ROI which because they need almost build a substation to which connect the the NZ national grid resulted in a zero ROI once all costs were accounted for.
Not deterred in the slightest he presented his work to their Board of Directors in person for them to finally ask why on earth should they even consider such a zero ROI venture.
This was some 20 years ago however I remember it well as the bottom line still applies and even more so today; the figures were/are calculated on today's energy prices and explain to me when your household power bill has not had an annual increase !

Several million was assigned to the project and as each year passed the forecasted ROI was exceeded.
Last I heard the were 4 or 5 one MW methane powered Cat gensets dealing to the landfill methane emissions and as luck would have it GloBull warming legislation came along for the power gen installation to also earn them carbon credits !  :scared:

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