i have been looking on this for an year+.. Here some current (online-shops) prices in Bulgaria.. say shop.chepakov.com / kameasolar.com
- panel 490Wp 2sq.m chinese = ~80E
- battery 5kwh Li chinese = ~1200E , non-chinese ~2000E+
- hybrid invertor+charger 4kw = ~800E chinese , ~2000E non-chinese
- grid and regulations:
-- day price: 0.15E/kWh, night: 0.09E/kWh
-- no such thing as spot prices - summer or winter, peak sun or midnight, no difference
-- can install anything AS LONG AS Nothing goes back into grid - and does not break other city/dwelling rules
if one gets the electronics from Germany - geizheis.de - prices are half, coz a) no VAT, b) less middlemen . Even some smaller things come with free postage - from Germany to Bulgaria ; i did buy several smaller chargers/inverters (5kg), while local sellers here have no such ideas. But anyway.
The (proven) efficiency one can get is about 50-60% per Wp (if there is sun). So.. it depends how much panels one can install as that is the monie-source, all else is monie-sink :/
Rough Napkin math, electronics with german prices, ~5 hours per day sun on average: 10 panels (1000E) + 2 batteries (2000E) + inverter (1000E) ~~4000E yielding on average 440kwh/month i.e. pay itself in 5-7+ years, mostly for summer loads. While 5 panels + 1 battery + inverter ~2500E -> ~220kwh/month -> 6-8+ years
BUT only IF you can use that much electricity, otherwise it will take much longer to repay. And, batteries have to be replaced probably in 5-7 years, depending on depth-of-discharge.
In most places here everything is electrical. i have convectors, boilers, stove, etc. No A/C. (all other electrics is maybe under 2kw in total). i use like day/night 400/250kWh in summer, 1400/800 kWh in winter. Some people have noisy heat pumps but doubt that changes things much.
If it was a separate house - i would have done it long ago. But it's a block of flats.
So... small Balcony stuff makes no sense (a very expensive UPS?), big balcony stuff (like putting those 5 panels as balcony's shade.. a) probably won't be allowed, b) only a short balcony faces south-ish.
The roof of the building is empty - 250sq.m - and can hold about 75 panels - but dividing that into 15 (or 50+ in higher buildings).. is not pretty. a) Making one single farm and splitting the bill/output seems the only reasonable way but does not work without completely rewiring the building's grid input and measurings; not doable without bunch of permissions/certifications ; while b) making 15 separate 5-panels-packs - is not much economical, plus few kilometers of cables.. And c) If only few people want panels on roof, maybe some form of renting the roof space from others who don't want.. may work for a while but as any renting, may go crazy.
So.. been sitting and thinking.. and recently seems only sitting..
it's easier than that. Take small cabbage heads (also works if cut into pieces, salad style). Put in some container - plastic tank, wooden barrel, glass jar, whatever - 2-or-20-or-120 liters. Add (sea) salt - 30-50g-per-liter-of-water (handwavey, can be corrected later), some grains of corn (or whole cob), a piece of apple, maybe some ginger, fill with water to cover the ingredients.. add something on top to keep things down, like river stone or heavy dish. Keep at below 15'C without freezeing (here usually in November, outside in the balcony.. until March). Once in a while have the water go up-down-up - which i do by just quickly kicking the jar for a minute.
Best eaten as salad with oil and red-pepper, and of course, wrapping pork minceballs.
> produced something more useful: a map of the fault lines where current practices are breaking and new ones are forming.
Here some story. Long time ago, i wrote a (software) accounting system. From 1st principles - nomenclatures, accounts, double-entry, transactions, balance (=current cached status), operations+reports on top of these. 5 tables (+1 for access control later). Very flexible and re-configurable into whatever one imagines. But anyway.
We deployed it at several places. The biggest one - retail with 50+ salepoints across whole region - was the most troublesome.. and after a month+ back-and-forth it dawned that.. they did have very well-working paper system of accounts/documents/data/values flow which was highly optimized for humans and the reality it was in (papers, remote places, delays, etc). Humans forget, make mistakes, displace things etc ; paper rots in time; distances make things out-of-sync - yesterdays invoices from village X will come tomorrow - maybe - .. etc. So their document flow - and even people-roles - were aligned with that system. Duplicating some things and completely avoiding others.
The new software had no such notions. There was no such thing as forgetting, displacing, out-of-balance. And while temporal stuff was fine, the document flow - even if consisting of same dot-matrix-perfect documents - was different to what they have used to. So.. it took them - and us - 3 months to retrain the personnel to unlearn their old system and to start actually using the new one properly, and enjoying the ride instead of fighting it.
Back to the topic.. i guess the old system of software engineering, built last 50+ years, has to be rearranged now. Not everything, but.. quite. Some things probably may wait for tomorrow, as the paper notes, but some - like roles and what they mean, and the cognitive/understanding chasm - is for yesterday..
Edit: after reading the whole paper, i think there are some things that can be "loaned" from hardware-design (chips etc) flows and processes. i see this analogy - the hardware's target environment (actual physical world, e.g. silicon etc) is also non-deterministic.. just mostly. Things like Requirements engineering, design-for-test ; all the enveloping (heat, power etc) and whatever else may come handy (i am not hardware dev, only seen these from aside, e.g. from a Verilog compiler)
when i moved to this apartment, the wooden wardrobe i had in previous one (built on the spot) could eventually move through that door and corners but absolutely could not move through this doors/corridors/corners (or staircase). So.. i got a power-jigsaw and cut it into upper and lower halves. Those moved easily. Then "assembled" them halves with lots of metal planks and screws on the new spot. Tadaa...
to curb the doomscrolling (laptop is as bad as phone) , i gave my father a big old Lego box - a Volkswagen beetle (which stayed for years, assembled by my kids.. which don't play that anymore. So i disassembled it). He had never tried those. Took him a week to build it, rearranged the room, studied the book like plant-specs-long-time-ago.. Then i gave another one, of similar size ~1500 pieces. i have one more ready-to-give "set". And then i plan to give him the rest 40kg well-sorted-but-in crates Lego, and the heap of model-books ~100+ , and let him do whatever he wants.. hoping he'll start improvising one day. Though.. may need a new empty room :/
i don't think optimization comes after translation.. it is a very small subset of translation and hence can be done easier, even per particular spot (or aspect), keeping more levels of abstraction intact - i.e. no need to change language, or, change (functional/containment) border-breaks, whatever.
Of course if there are semantically correct ways of translation, optimization might be easier than without it.. For the defined semantics. But can still be hard on (or including) all other not-well-defined fronts.
Well, depends on what "translation", and "optimization", means. If even shuffling a few things around counts as translation, then yes.. But then (near?) every change is translation, so it becomes meaningless as a notion. Better keep it more substantial, for changing some essential expressive ingredient of the code without changing functionality (and structure/architecture?) , much. Like language.
Sometimes translation may bring (speed) optimization, sometimes not (like python<->C) - some redundant loop in C will be faster than same loop in python, but removing it entirely would be even faster.. and no need for a translation just for that.
You probably think of "transformation" as general term, but that is much more primitive than "translation".
it used to be that coding was veeery tough and tedious thing, so specifications had to be really well pre-chewed, down to the bone. Think 60ies and 70'ies .
Each decade after that, less and less of the specification is being ever written, and it is/was left to the programmer to finish it as they seem fit, and more and more programmers became (business-) domain-experts. Just see job ads for last (20?+) years - half is software-stuff, half is domain-knowledge required.
so.. do you think there's some reset happening/pending? So there is more specification being written? Or is it faster prototype-and-throw-away loop, and at the end the spec is "make it like this but prdocution grade" - instead of (again) actual proper specification with all the whys/whats/hows in it ?
https://fuelo.net/cheap/where?lang=bg&order=cheap&fuel_type=...
come here, the water is fine :)
reply