robinlawrie
New Member
Hi all, newbie here. Im restoring an old countryside school in southern Italy. It will be our house. its 300 sq metres, flat roof , 50cm tuff stone walls.
Unfortunately most of the state financing which was supposed to assist us, has just been stopped (new government) , so we are left with a budget that is much too small for the building.
One thing we can still get financial assistance with is a heatpump.
This means a big old heatpump to offset the lack of insulation we can no longer afford. probably at least 20kw, more likely 25.
I will be digging into my "emergency fund" to build out a pv system (im handy with electronics and building stuff generally, and have a tame local electrician who will help make sure its all wired properly. ) , without which, the heatpump will be insanely expensive to run (20+ euro cents per kwh here...)
(one saving grace is we will hopefully also have a 30kw wood/pellet fired fireplace (water heating) which can substitute/assist the heatpump when its cloudy/too cold/night etc.. , so if careful we can avoid too much grid consumption, without consuming 1000kg of wood a day)
the other saving grace is we have lots of sun and a massive south aligned flat roof with almost no shade.
not knowing the exact model of heatpump (the engineer will be sizing the system) im not sure of exact requirements. however ive seen a few 25 kw heatpumps which suggest an 11kw circuit breaker, so that seems a good ballpark for how much it *could* consume on a bad day.
obviously all the other household loads need considering too..
note that feed in tariffs here are so small as to generally not be worth the hassle.
im imagining a system which will use pv/batteries where possible, and take from the grid when necessary. I'm guessing 3 phase is necessary.. Here any residential connection over 6 kw is provided as 3 phase apart from in special circumstances.
That leads to my questions:
*if i build out a system with a hybrid inverter.. size the inverter for say 15kw, but put in (for now, to expand as funds allow) only 5kw of panels and a modest battery (maybe 4.8kwh pylontech or similar), can it be set up to mix what is produced with the grid input to provide the required power even if over the pv / max battery output? ive never really understood if the output is either pv/battery OR grid, or can be a mix of the two.. (considering if set to avoid grid feed-in too)
* if i get a 10kw grid contract (more than 10kw the prices shoot up) can the battery be used to handle peaks above that, or is that just a terrible idea? it never really gets below -2C here, although we did have a freak week a few years ago where it hit minus 11C for a couple of days.
*is it better/cheaper to get 3 single phase inverters or a single bigger 3 phase one? i was looking at the growatt ones, but ive since read some horror stories here that put me right off. im on a tight budget but dont want fireworks!
alternatively i could build a system with separate charge controller, inverter etc... whatever costs less without sacrificing reliability and future expandability.
obviously id love to build a full 15kw setup immediately with 10's of kwh of batteries... but that will have to come later.
of course it may well be cheaper to just get a grid tie inverter despite the low tariffs, but i really want the option to add batteries in the near future if not immediately.
Last year the Russia thing cause electricity prices to spike at nearly 60 euro cents a kwh.... its also, like most things italian, a bit of a bureaucratic nightmare to get a diy solar system of any size connected to the grid if there is even a chance of feed-in happening.
The easy alternative to have a pro set up a system would double my costs and take the fun away.
Basically... ANY suggestions about how to spec out a useful solar system with the above requirements and a limited budget would be most appreciated.
many thanks, Robin.
Unfortunately most of the state financing which was supposed to assist us, has just been stopped (new government) , so we are left with a budget that is much too small for the building.
One thing we can still get financial assistance with is a heatpump.
This means a big old heatpump to offset the lack of insulation we can no longer afford. probably at least 20kw, more likely 25.
I will be digging into my "emergency fund" to build out a pv system (im handy with electronics and building stuff generally, and have a tame local electrician who will help make sure its all wired properly. ) , without which, the heatpump will be insanely expensive to run (20+ euro cents per kwh here...)
(one saving grace is we will hopefully also have a 30kw wood/pellet fired fireplace (water heating) which can substitute/assist the heatpump when its cloudy/too cold/night etc.. , so if careful we can avoid too much grid consumption, without consuming 1000kg of wood a day)
the other saving grace is we have lots of sun and a massive south aligned flat roof with almost no shade.
not knowing the exact model of heatpump (the engineer will be sizing the system) im not sure of exact requirements. however ive seen a few 25 kw heatpumps which suggest an 11kw circuit breaker, so that seems a good ballpark for how much it *could* consume on a bad day.
obviously all the other household loads need considering too..
note that feed in tariffs here are so small as to generally not be worth the hassle.
im imagining a system which will use pv/batteries where possible, and take from the grid when necessary. I'm guessing 3 phase is necessary.. Here any residential connection over 6 kw is provided as 3 phase apart from in special circumstances.
That leads to my questions:
*if i build out a system with a hybrid inverter.. size the inverter for say 15kw, but put in (for now, to expand as funds allow) only 5kw of panels and a modest battery (maybe 4.8kwh pylontech or similar), can it be set up to mix what is produced with the grid input to provide the required power even if over the pv / max battery output? ive never really understood if the output is either pv/battery OR grid, or can be a mix of the two.. (considering if set to avoid grid feed-in too)
* if i get a 10kw grid contract (more than 10kw the prices shoot up) can the battery be used to handle peaks above that, or is that just a terrible idea? it never really gets below -2C here, although we did have a freak week a few years ago where it hit minus 11C for a couple of days.
*is it better/cheaper to get 3 single phase inverters or a single bigger 3 phase one? i was looking at the growatt ones, but ive since read some horror stories here that put me right off. im on a tight budget but dont want fireworks!
alternatively i could build a system with separate charge controller, inverter etc... whatever costs less without sacrificing reliability and future expandability.
obviously id love to build a full 15kw setup immediately with 10's of kwh of batteries... but that will have to come later.
of course it may well be cheaper to just get a grid tie inverter despite the low tariffs, but i really want the option to add batteries in the near future if not immediately.
Last year the Russia thing cause electricity prices to spike at nearly 60 euro cents a kwh.... its also, like most things italian, a bit of a bureaucratic nightmare to get a diy solar system of any size connected to the grid if there is even a chance of feed-in happening.
The easy alternative to have a pro set up a system would double my costs and take the fun away.
Basically... ANY suggestions about how to spec out a useful solar system with the above requirements and a limited budget would be most appreciated.
many thanks, Robin.
