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Green Building Bible, Fourth Edition
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    •  
      CommentAuthorDamonHD
    • CommentTimeJul 15th 2018
     
    I have started a write-up revisiting my attempt ~7 years ago to fit some grid-attached storage:

    http://www.earth.org.uk/electricity-storage-whole-household-2018.html

    The market has moved on, and though I'd still be paying more in raw storage terms than for my lead-acid gel off-grid battery storage of that time, this is packaged, installed, with data access, etc. And done right meets G83 and G100 and shouldn't upset my current FiT arrangements.

    I'm not doing this to save money. I'm doing this partially experimentally and mainly as a (small, expensive) carbon-reduction exercise, reducing grid losses/strain shipping energy in and out of the house.

    There may be a bigger store added in parallel with this later, even up to seasonal store.

    ... If the council doesn't pull my house down under CPO in the interim.

    Rgds

    Damon
  1.  
    Damon, wouldn't it be better for the environment if you exported the solar energy and displaced some fossil generation?

    The premise of the FIT and export tariff is that those of us without solar, should subsidise those of you with solar to export it, to everyone's net benefit. Grid tied storage feels like that bargain is broken, though not as bad as immersion diverters.

    What does the carbon intensity data on this say? Haven't checked earth.org for a while.
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 15th 2018 edited
     
    It *is* best to displace ff generation on the grid with solar.

    This doesn't change the amount of that displacement that happens (ie net exports are the same), it simply stops some of the back-and-forth across the local distribution system which is lossy and puts a strain on the local grid. This can also shave some peak-time loads by shifting when residual load is presented to the grid.

    The losses in grid vs the battery are probably a wash, even with an efficient lithium-chemistry system.

    But avoiding using the grid as if it were a battery is a good thing. Shaving peak demand is a good thing, and almost certainly a (carbon) saving one way or another IMHO.

    Rgds

    Damon
  2.  
    Hi Damon, shouldn't people export solar during the daytime peak when grid intensity is high, then import at night when intensity is lower? You have written extensively on this.

    Do people still claim Export tariff at deemed 50% of generation, even though they are not exporting anything? Paid for by me! but also by the folk on the sharp end of the energy poverty wedge. This encourages people to dump publicly-subsidised solar power into immersion heaters.
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 15th 2018 edited
     
    So, I would still (in winter, say) be running my dishwasher overnight and importing the bulk of that then. (I might only be able to supply ~25% of peak ~2kW demand from local storage.)

    The question of what actually fires up to deal with an extra 1kW of grid demand, eg because someone stopped spilling PV generation to grid, remains open. It's probably CCGT most of the time, but when there is no pumped storage being released to grid I take it that shifted grid demand at that time is effectively extra grid storage. But also look at:

    https://blog.tmrow.co/using-machine-learning-to-estimate-the-hourly-marginal-carbon-intensity-of-electricity-49eade43b421

    I'm still in several minds about diverting PV to resistive heating for many of the reasons you outline and that I have raged on before. But if that storage is efficient (eg such as Sunamp's v low losses compared to an actual hot water tank) or you are relieving the grid of peak flows around solar noon, then it may be less bad though to actually good. (If that heat storage were via a heat-pump preserving exergy, then I see that as being likely much better.)

    But generally doing whatever is possible to reduce peak demand (and flows) by importing less or exporting more is good. A flat grid demand (or matching intermittents' availability) is a cheaper and lower-carbon one, I think.

    Rgds

    Damon
    • CommentAuthorowlman
    • CommentTimeJul 15th 2018 edited
     
    <blockquote><cite>Posted By: WillInAberdeen
    The premise of the FIT and export tariff is that those of us without solar, should subsidise those of you with solar to export it, to everyone's net benefit. Grid tied storage feels like that bargain is broken, though not as bad as immersion diverters.

    Immersion diverters are simply an automated device replacing a manual switch. If some that power would be going into a DHW tank anyway what is the problem. There is a limit to what can be used, and once up to temperature it simply all goes into the grid as before. Whether that load is part of the house baseload, locally produced, at midday or early evening, from the grid, seems top me to be be at the heart of what Damon is thinking with storage batteries, and immersion diverters are no different, the DHW tank is a battery of sorts.
    BTW I don't have one, nor batteries.
  3.  
    Hi owlman, immersion diverters encourage people to heat water with electricity, when they could/should use gas to heat water in their high-efficiency boiler and export the solar to displace a low-efficiency gas power station.

    When people do this, it roughly doubles the co2 emissions overall, but people do it to pocket the 'deemed' export tariff and then not actually export anything. So the subsidy regime actually rewards people who increase co2 emissions, at the expense of most other bill payers who don't have the option of solar.
    • CommentAuthorowlman
    • CommentTimeJul 15th 2018 edited
     
    Hi Will, I understand what you're saying. However the one size fit's all approach to your conclusion is IMO flawed. You assume that everyone has a gas boiler, there are situations where this is not so. There are also plenty of cases where DHW is heated by electricity, with CH or home heating coming from other sources, or maybe even not at all in high efficiency homes. For this group their immersion DHW heating is not done to game the FIT system but driven by necessity. Using peak Solar to do that doesn't seem wrong but common sense, for the same grid alleviation reasons that Damon was theorising on, although I doubt they do it for that reason either.
    Either way the ammount of displacement energy I think would be very low all things taken into account. That diverted solar electricity is unlikely to shut down a gas power station.
  4.  
    Fair enough, although anyone with the funds and motivation to install panels and a pv diverter, is well able to install a multipoint water heater on gas or bottled-LPG.

    Not so much criticising the people who do this btw, it's the system that is crying out to be gamed.

    I'll stop 'diverting' Damon's thread now!
  5.  
    Damon, you mentioned storing solar power to run dishwasher and washing machine overnight. Would you get the same effect if you just run them during the daytime solar generating period? maybe develop some software using the weather forecast to decide when the optimum time would be, interface the delayed start function of the appliance?

    You also mentioned storing power to run the fridge/freezer overnight. Would you get the same effect by chilling them down during the day then switching them off overnight, maybe with some freezer blocks or bottles of salty water to act as stores of cold? Use a time switch or a pv diverter to switch them back on during generation times?
    • CommentAuthortony
    • CommentTimeJul 16th 2018
     
    +1 and no battery replacement cost either
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 16th 2018 edited
     
    Hi,

    When it's sunny I do try to run the dishwasher during the day.

    However if it's at all cloudy it can be hit and miss. If the generation is not >> 2kW for the entire first hour or so then the couple of spikes of consumption while heating water may not be fully covered by generation. Batteries could partly or fully fix that.

    Also, when it is sunny, I do attempt to take the opportunity to load up the fridge with beer or wine to store cool, yes, but that's going to be small fry. And I'm not going to risk damaging the fridge or our health messing about with turning them of or off. I already bought the most efficient I could that fitted our requirements:

    http://www.earth.org.uk/note-on-Siemens-KG34NA10GB-upright-fridge-freezer-REVIEW.html

    The washing machine timing is more tricky because it has to fit with drying days, etc, but we tend to run it to finish when we get up, which while not minimum grid demand and CO2, is better than peak. And we run very few hot washes; a fair percentage are run cold:

    http://www.earth.org.uk/note-on-Zanussi-ZWD14581W-freestanding-washer-dryer-REVIEW.html

    Rgds

    Damon

    PS. I used to have my system automatically start my old dishwasher at a 'optimum' time by turning on the power. But the new one with electronic controls starts in a silly state sometimes and that is not possible. Something like Green Bean https://github.com/GEMakers/green-bean would be lovely, but I don't have access to any such thing.
  6.  
    I'm also starting to consider adding a battery to my solar setup. The ideal would be to add a Growatt SP1000 to the 1.8kw (1500w at the invertor) solar array that we have installed on the woodshed roof. The Growatt is DC coupled to the solar panels and seems really straightforward for a DIY installation. I also like the idea of the batteries not being in the house in case of a fire.

    The only issue I have is that the woodshed is detached from the main house and the SP1000 box would be located about 18m away from the house meter box, so I am not sure how I'd attach the sender unit to the mains supply to allow the battery to know when I have excess electricity. If anyone has any suggestions, I'd be grateful?

    Note, the 1.8kw array is an extension to an existing 4kw array and so doesn't receive FIT payments or export payments.
    •  
      CommentAuthordjh
    • CommentTimeJul 17th 2018
     
    Posted By: Pile-o-StoneThe only issue I have is that the woodshed is detached from the main house and the SP1000 box would be located about 18m away from the house meter box, so I am not sure how I'd attach the sender unit to the mains supply to allow the battery to know when I have excess electricity.


    According to http://www.solartubecompany.co.uk/power-saving/growatt-battery-storage/growatt-sp1000/

    "The Sensor is connected vial an RJ45 cable which has a range of up to 20m"

    So I'm not sure where the concern is. (nor exactly what an 'RJ45 cable' is nor why it is limited to 20 m.)
    • CommentAuthordereke
    • CommentTimeJul 17th 2018
     
    Hmm RJ45 is the plug on the end of a network cable.
    The cable can be of a few varieties, CAT 5, CAT 5e, CAT6, CAT6e

    These all support different max speeds. The 5e/6e are shielded which stops interference and usually boosts the max length they can work over.

    Sounds like the sensor probably doesn't actually talk over ethernet so the shielding might not make a difference.
    •  
      CommentAuthordjh
    • CommentTimeJul 17th 2018 edited
     
    Posted By: derekeHmm RJ45 is the plug on the end of a network cable.

    Well, it's certainly a plug. It's definitely not a cable, and as you say it is commonly connected to different sorts of cables used for networking amongst other things, but it could be connected to some other cable. In short the description tells us nothing at all about the cable.

    The 5e/6e are shielde

    No, the e stands for enhanced I believe and refers to the enhanced crosstalk specifications of cat5e. There's no such thing as cat6e, but there is cat6a (augmented).

    Shielded versus unshielded is something different again and all types can be bought in either type, AFAIK.
    • CommentAuthordereke
    • CommentTimeJul 18th 2018
     
    I stand corrected!
    • CommentAuthorgravelld
    • CommentTimeJul 18th 2018
     
    Thanks for the write up Damon. Kind of disappointing we're not at storage/import price parity yet. I'm thinking/hoping we might be at the time I'm "due" to change inverter in about five years. I wonder if there might be any combined kits of inverter and storage which makes it better value.

    It would be interesting to see PV sales figures for the UK - my suspicion is that a lot of people purchased a year or two either side of me, so there may be bunch of people coming up for inverter replacements at the same time.
    • CommentAuthorskyewright
    • CommentTimeJul 18th 2018
     
    Posted By: gravelld
    It would be interesting to see PV sales figures for the UK

    In the domestic market (which is what I think you're interested in?) the number of FIT registrations in various time periods might be an alternative figure to look at to check your suspicion.
    I'm not certain but I think that sort of data is fairly readily available?
    • CommentAuthorgravelld
    • CommentTimeJul 18th 2018
     
    Probably! Just an idle thought as I was writing the first para.
  7.  
    Posted By: djhhttp://www.solartubecompany.co.uk/power-saving/growatt-battery-storage/growatt-sp1000/


    Thanks for the information, I'll need to bury the cable so that might need additional length, but I'll have a look at the weekend.
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 18th 2018
     
    FiT registration data is certainly available, at quite fine grain. (BEIS)

    PV sales plummeted this year with the FiTs withering.

    The inverter for my first round of PV is 10 this year, so nominally due to fail sometime soon!

    Curiously, when I bought lead-acid for my off-grid ~7Y ago system I paid something like £400 per usable raw kWh of storage, and would be paying several times that for shiny packaged new grid-interactive Li-chemistry storage. But is time around it's pretty much guaranteed for 10Y+ and has lots of data collection built in.

    Rgds

    Damon
    •  
      CommentAuthordjh
    • CommentTimeJul 18th 2018
     
    Posted By: Pile-o-Stone
    Posted By: djhhttp://www.solartubecompany.co.uk/power-saving/growatt-battery-storage/growatt-sp1000/


    Thanks for the information, I'll need to bury the cable so that might need additional length, but I'll have a look at the weekend.

    I'd check with the makers if you're in doubt. They'd be able to confirm how tight the spec is and whether it can be extended if needed by upgrading the cable or whatever. Or just suck it and see. But make sure it works before filling in the trench!
    •  
      CommentAuthorfostertom
    • CommentTimeJul 20th 2018 edited
     
    It's totally in the national/planetary interest to promote networking of captured power, incl storage, at all possible levels, from just with next door neighbour, up thro small local mini-grid whether via the Grid or co-op-built independent grid, all smart-controlled, and - vitally - capable of continuing to operate seamlessly even when the Grid goes down.

    Total max Distributed capability is future-robust, cyber-terrorist proof, and eventually almost-free.

    Beside that imperative, worries about 'who's subsidising who', and tech/saftey considerations of rule-making, incumbency-preserving Grid operators, need to be put aside asap.

    So if that's your thought and intention and direction - kudos!
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 20th 2018
     
    My goals are not that lofty! We continue to use a grid because it's effective and reliable, and can be made green.

    But yes, if more parts are individually robust, the system as a whole should be more so too.

    This is really for me to tinker and develop ideas, maybe for future products once Radbot is thriving on the market.

    Storage will get cheaper, much cheaper. But never free because we'd already have done it and because physics!

    Rgds

    Damon
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 23rd 2018
     
    I've put down a deposit on a modest solution which should get installed in a couple of weeks. I shall be very interested to see how it performs from now into mid-winter.

    Rgds

    Damon
    • CommentAuthorowlman
    • CommentTimeJul 23rd 2018
     
    Good luck Damon; As an adjunct to your musings on battery storage I recently took another look at Solar power diverters and like you I thought they were only suitable for resistive loads. However one company was saying that with the addition of a relay to their device you could have input into inductive loads. The same company also has entered the field of battery storage, presumably trickle charged via their diverters.
    •  
      CommentAuthordjh
    • CommentTimeJul 23rd 2018
     
    Posted By: owlmanHowever one company was saying that with the addition of a relay to their device you could have input into inductive loads.

    Presuming the relay/contactor was suitably rated that should be possible. But most diverters will divert arbitrary fractions of the power and connect and disconnect frequently and arbitrarily. I can't think of many inductive devices that are designed for an intermittent supply like that.
    •  
      CommentAuthorfostertom
    • CommentTimeJul 24th 2018
     
    Posted By: DamonHDStorage will get cheaper, much cheaper. But never free because we'd already have done it and because physics!
    Once waged humans are finally taken out of the production cycle, from logistics thro management/banking to mining raw materials or deep recycling of current materials stock, like we've never had a chance to do it previously, and despite/because of physics, then 'zero marginal cost' won't just be marginal, but everything. Things only cost when kept scarce.
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 25th 2018
     
    AFAIK, given technology as currently available, storage costs are nothing very much to do with economics or artificial scarcity or economic inefficiency. As things stand, storing lots of cheap energy (upon which civilisation depends) is intrinsically hard and thus expensive in fairly absolute terms. kWh of electricity storage should/could/may displace (say) gold as a robust measure of value.

    Rgds

    Damon
   
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