getting around Italian bureaucracy.

[robinlawrie]

Ok so im still trying to plan a solar setup that will do what i want within my budget. The house has a 3 phase grid supply currently on a contract limited to 6kw. 3 phase becuase it was previously a small countryside school..

Given the current very low price of solar panels, my large flat roof, and abundant electricity consumption, im aiming for a 10-15 kw array.

Paired with a suitable inverter ( this, seems suitable: https://voltaconsolar.com/products/hybrid-solar-inverter-15kw-three-phase-48v)

and a 20 -30 kwh battery setup (a couple of seplos Mason with EVE cells seem an excellent value choice) .

This is all fine, until you come to the laws (these may be the same everywhere, but given italy is famous for having millions of rules, maybe not)


Over 6kw, a certified engineer must design the system ($$$)

Over 6kw, a govt. inspection is required every few years ($$)

any system connected to the grid must be installed by a certified contractor ($$$)

Any inverters connected to the grid must be CEI certified and MUST NOT provide power to the house in the case of a blackout, to avoid risk of back-feeding to the grid.

Software settings on hybrid inverters are not considered sufficient, and these devices are illegal to install unless off-grid.

Now i can understand the thinking behind all of these rules..

however they get in the way of me making a nice semi off-grid system within my budget, taking from the grid only when solar/batteries are insufficient.

Considering economic solutions, I thought that it might be possible (maybe it has a name already?) to create an off-grid system which powers the entire house. , but connect the grid to a nice big three phase 48v battery charger (forklift charger? or something designed specifically) . The output of which charges the same batteries the off-grid inverter does.

Some kind of control logic tells the charger to switch on when the battery soc drops below a certain threshold and/or when the inverter isnt charging the batteries. (maybe the inverter has the abilty to control this)

That way i have no direct connection to the grid, no risk of back-feeding, and avoid all the paperwork and fees.

The only downsides i can see are:

1. wasting excess power however the tariffs here pay you practically nothing so, not so bothered, im sure i can find something to do with the juice.. ( heated pool, diy thermal store? lots of ideas)

2. round trip efficiency, always going via the batteries.. ill probably waste quite a few percent..

3 added cost of charger.. this is much less than the cost of the paperwork and a professional installation would be.



Anyone care to offer thoughts on this idea? disadvantages? links? i assume some variation on the theme has been done many times before but i dont know how to search for it. ?

thanks, Robin.

 

[Luk88]

Hi,

These rules read very similarly to the rules we have in Poland, except the "Over 6kw, a govt. inspection is required every few years". I never heard about that one here. Let me tell you how we deal with it around here. Perhaps it is of some help, but if I was you I'd look for local information,local forums if there are any etc.

First let me just say one thing. Is your current grid supply 6kW total (just 2kW per phase) or 6kW times 3 = 18kW total? Also what loads are you running? It may be easier to convert most of your critical loads (these you want powered during an outage) to one phase to avoid 3 phase imbalance.

So about those rules:

Over 6kw, a certified engineer must design the system ($$$)

Can you buy a ready made design? Are there any available?

Which part of the system causes this requirement? The battery, the inverter? The fact it is grid tied? Or over 6kW of PV? Is it possible to make your system fit just below the requirement and then extend it in a way that doesn't break the rules?

Over 6kw, a govt. inspection is required every few years ($$)

Same as above.

any system connected to the grid must be installed by a certified contractor ($$$)

This is the same here, but what is the certificate the contractor has to have? Does it have to be a solar/renewable /battery bank certification or is a domestic electricity contractor sufficient(read the law, read the forms, how is this certification verified? I only found out a non-solar electrician can do it here because on the permitting submission form where it says installer qualification it has a space to select solar or domestic/industrial. If the latter, it will be a lot less expensive and you might be able to find a guy that will check your work and sign it. Of course you need to know what you're doing.

Any inverters connected to the grid must be CEI certified and MUST NOT provide power to the house in the case of a blackout, to avoid risk of back-feeding to the grid.

Same here. There are some solutions. The easiest from the regulatory point of view is to start with a simple on grid system with no battery. Get all the permits and inspections sorted. Then add an AC coupled battery system like one with Victron Multiplus II. I can't say if this is legal in Italy (I'd expect the rules to be similar in the EU, but who knows) but hopefully you can add such a device without any additional permitting. Read on AC coupling. It has no capability to supply power on the grid side, but when the grid is on I believe it passes through excess power generated by the (already permitted) on grid inverter. There are many people with knowledge of Victron gear that will correct me if I'm wrong here.

Alternatively do what I'm planning to do. Once you have a battery less on grid system (all permitted and inspected) add an off grid inverter with more solar or just charging from AC with a chargeverter downstream. It all depends on what makes sense from the regulatory standpoint where you are. I spent months researching it here.

Software settings on hybrid inverters are not considered sufficient, and these devices are illegal to install unless off-grid.

Same here, but it is not really a software problem. There is a physical limitation the way these operate. They measure the current coming from the grid (how much the house is using) and they try to match it, but there are two issues. One they cannot respond as fast as the load changes. Two, it is impossible to measure and match very small currents without possibility of backfeedeing. And none of these "hybrid inverters" i know support the grid control by frequency (I forgot the standard name, all certified on-grid inverters support it so the grid can tell them to stop sending power). So essentially they backfeed into the grid at random times. This is why they are not allowed.

 

[robinlawrie]

Thanks so much for the detailed reply.

Regarding the 3 phase system, it works like this here: Over 6kw (10kw in certain areas) , you are required to get a 3 phase supply. This is (i believe) due to less stress on inadequate infrastructure. I decided to keep the exisitng 3 phase setup to future proof our new wiring system.

however, in a typical contradictory Italian way, even if you have a 15kw 3 phase system, the grid will allow you to use 15kw split over the 3 phases, but also allow 15kw on just on one of the phases. 15 kw total however you slice it, basically.

Ive no idea why. according to the guy designing our new wiring, this is a rule that was introduced 5 years ago.. before that, yes, i would have been limited to my tiny 2kw per phase. It does seem to make the 3 phase requirement somewhat unnecessary.

could you maybe explain better (a quick diagram?) what your proposed arangement is? im having a hard time picturing it, but seems to requre 2 inverters and a charger?

any thoughts in my idea?

thanks again!

 

[kommando]

I run 2 systems, one grid tied limited to 3.68Kw which is the max allowed in UK without prior approval and an off grid Sunny Island based set up with lithium batteries. When the production is high enough I switch the grid tied over to the off grid fully isolated from the grid, all inverters are controlled by the SI's using frequency shift. Currently can be off grid 6 months of the year and will add more panels this year to take it to 8 months. During the low production months the off grid solely charges the batteries, which can be used overnight or kept full for grid shutdowns.

 

[OffGridForGood]

connect the grid to a nice big three phase 48v battery charger (forklift charger? or something designed specifically) . The output of which charges the same batteries the off-grid inverter does.

EG-4 Chargeverter (single phase each x 3?)
Just got mine installed recently and love it/wonder how I got by without it!

 

[Luk88]

Thanks so much for the detailed reply.

Regarding the 3 phase system, it works like this here: Over 6kw (10kw in certain areas) , you are required to get a 3 phase supply. This is (i believe) due to less stress on inadequate infrastructure. I decided to keep the exisitng 3 phase setup to future proof our new wiring system.

however, in a typical contradictory Italian way, even if you have a 15kw 3 phase system, the grid will allow you to use 15kw split over the 3 phases, but also allow 15kw on just on one of the phases. 15 kw total however you slice it, basically.

This is actually good, because it lets you put all your critical loads on one phase if you wanted.

A single phase system is much simpler and if you use victron (or other more expensive gear) you can often expand into more phases.

It would be useful if you listed your loads. Do you have a water heater if so tank or tankless, induction stove? Etc? These are the thing people usually have tgat are high power loads.

Ive no idea why. according to the guy designing our new wiring, this is a rule that was introduced 5 years ago.. before that, yes, i would have been limited to my tiny 2kw per phase. It does seem to make the 3 phase requirement somewhat unnecessary.

could you maybe explain better (a quick diagram?) what your proposed arangement is? im having a hard time picturing it, but seems to requre 2 inverters and a charger?

There are many possible arrangements. You'll have to research them and decide which one is best. The simplest Ac coupled system with the Victron Multiplus II looks like this:

What they call "no break loads" is really a critical loads panel.

This by no means the only option. Just one of many.

any thoughts in my idea?

thanks again!

The one with 10-15kW of solar, 30kWh of battery and 3phase inverter. I have no experience with this inverter. Regarding sizing it really depend on the loads.

This inverter is called hybrid, it has "grid tie operation" but it is unclear to me if it can send power to the grid and if its certified to do so. Even if it is, you're probably going to be much better to consider it as an off grid - with grid backup. Here you wouldn't need any permits for something like that. (it is still good to have a certified contractor involved in case you'll have an insurance case in future etc).

These kind of off-grid-with-grid-backup inverters have certain disadvantages. Fairly high no load /low load energy consumption. All or nothing approach to grid (they can't power 90% of your loads from the battery and just top up for 10% from the grid as necessary. To use the grid charger all your loads switch to the grid which with no power sold to grid may be costly or may be perfectly fine depending on your circumstances.

If this is really a hybrid inverter with on grid (selling power) capability it has to be certified to be used anywhere in Europe.

 

[robinlawrie]

The one with 10-15kW of solar, 30kWh of battery and 3phase inverter. I have no experience with this inverter. Regarding sizing it really depend on the loads.

This inverter is called hybrid, it has "grid tie operation" but it is unclear to me if it can send power to the grid and if its certified to do so. Even if it is, you're probably going to be much better to consider it as an off grid - with grid backup. Here you wouldn't need any permits for something like that. (it is still good to have a certified contractor involved in case you'll have an insurance case in future etc).

These kind of off-grid-with-grid-backup inverters have certain disadvantages. Fairly high no load /low load energy consumption. All or nothing approach to grid (they can't power 90% of your loads from the battery and just top up for 10% from the grid as necessary. To use the grid charger all your loads switch to the grid which with no power sold to grid may be costly or may be perfectly fine depending on your circumstances.

If this is really a hybrid inverter with on grid (selling power) capability it has to be certified to be used anywhere in Europe.

The inverter chosen is irrelevant really.., ill choose a suitable one when i have a clearer idea on the system i want. likely next year.

Currently all my money is going into restoring the building (including all new wiring,plumbing/heating etc.)

It was more the idea of having an off-grid system, "isolated" from the grid (for that you need no permission here) BUT, with a big charger attached to the grid (allowed, its just a battery charger) which is connected to the same batteries as the off grid system. the only connection between the two systems is at 48v via the batteries.

it seems, apart from conversion losses, which might be significant, and loss of grid feed-in option (the tarrifs are tiny here) that it should work, but i dont know if im missing something, or if there is a better option that wont cost significantly more.

regarding loads, apart from the usual appliances we will have:

1. a 15kw heat pump, which is undersized for the property actually, but will be paired with a 26 kw wood/pellet stove, which can be used if its really cold/at night, or we have no sun.

2. a heat pump hot water heater.. no idea of power rating yet

3. my PC workstations i use for work. i do 3d animation, so they are VERY powerful machines that are often left running on full blast for days.. each consumes about 700w when going full-on, and i have 2, and may get a third.

4. cnc machine. used rarely, but has a 3kw spindle and can be running for hours at a time

5. kiln for ceramics, this is a future purchase.. but they dont sip power.

6. electric car charger. again, a potential future purchase, no electric car yet.


as you can see i could probably do with a 100kw solar system, but hey you cant have everything!

 

[Hedges]

Here is another 3-phase hybrid to consider.
This doesn't get around all your red tape problems, but it is a tier-1 company, should avoid you having technical issues.

Sunny Tripower Smart Energy | SMA Solar

www.sma.de

 

[robinlawrie]

Here is another 3-phase hybrid to consider.
This doesn't get around all your red tape problems, but it is a tier-1 company, should avoid you having technical issues.

Sunny Tripower Smart Energy | SMA Solar

www.sma.de

thanks, appreciate any suggestions. i wonder if it is compatible with diy style 48v batteries? these proprietary battery systems are so damn expensive.

I am also qusationing wether a 3 phase inverter is even necessary at this stage, given what i have found out regarding the fact that the 3 phase grid supplies here are capable of supplying their full capacity on a single phase.

This suggests that the house wiring wont pay much attention to phase balancing.. ill need to speak to electrician.

Maybe they plan just to stick all sockets on a single phase.. ive only specified a handful of full 3 phase sockets in the project, one in the garage for an ev charger, one in the workshop for tools, and one in the service room for potential 3 phase heatpump (although i believe the engineer has specced a single phase one)

Even if the wiring is split into approximately load balanced circuits, maybe, if i am going the "off grid" route, and breaking the grid connection to the house wiring, i could wire the circuits that will originally be connected to seperate phases of the grid supply, all to a big single phase inverter output.. again , need to speak to an electrician.. i dont know enough about 3 phase to know if this can be done.

 

[kommando]

In the UK single phase is installed with up to a 100A fuse, that's 24Kw at the normal 240V they set the supply to even though its supposed to be 230V. I have the 100A fuse on single phase and consumer circuit board to suit but never see higher than 7kw peak usage, the two Sunny Island s can do 10kw. Must fit a 9kw electric shower just to see what happens.

 

[robinlawrie]

just in case my description wasnt clear, i made a diagram. would it work? are there other options that wont cost a fortune? basically nothing with the capacity to feed-in can be connected to the grid, legally, and only an off-grid system can be legally built "DIY" this seems like a potential solution, which, i am sure has many drawbacks.

 

[OffGridForGood]

just in case my description wasnt clear, i made a diagram. would it work? are there other options that wont cost a fortune? basically nothing with the capacity to feed-in can be connected to the grid, legally, and only an off-grid system can be legally built "DIY" this seems like a potential solution, which, i am sure has many drawbacks.

Thats exactly how my system is connected.

 

[hwy17]

Yes. I call this double conversion and my system works this way too.

The main drawback is you lose 5-10% of the power through the charger and 5-10% again in the inverter, so all grid imports suffer up to 20% efficiency loss.

 

[robinlawrie]

ok well its good to know that its possible and i would not be the first, although a 20% penalty is pretty severe!

out on interest what are you both using as chargers? the batteries i have in mind can take up to 400 amps (bms limit) but i cant imagine having an electricity contract that can supply 20kw. current contract is 6kw.. so that would be 125 amps max

 

[kommando]

although a 20% penalty is pretty severe!

20% loss to battery. Analyse your usage profile vs PV output and see what % you will need from the grid vs PV. And some of the PV will go direct to internal usage without touching the battery.

 

[OffGridForGood]

ok well its good to know that its possible and i would not be the first, although a 20% penalty is pretty severe!

out on interest what are you both using as chargers? the batteries i have in mind can take up to 400 amps (bms limit) but i cant imagine having an electricity contract that can supply 20kw. current contract is 6kw.. so that would be 125 amps max

I am using the EG-4 Chargeverter V1 (the bright yellow model) connected to a grid source 240V 30A single phase, output is "48v" DC - the programable settings allow setting whatever peak DC voltage you want for your batteries. Main advantage is the ability to apply a charge while the inverter continues to supply loads from battery. Zero chance of backfeed to the grid.
Your three phase set up, may work best with three of these?

there are also links on the forum to some well made used telecom chargers but these are not adjustable voltage so you have to pick the voltage you want and order the correct one - price is super.

 

[hwy17]

ok well its good to know that its possible and i would not be the first, although a 20% penalty is pretty severe!

out on interest what are you both using as chargers? the batteries i have in mind can take up to 400 amps (bms limit) but i cant imagine having an electricity contract that can supply 20kw. current contract is 6kw.. so that would be 125 amps max

I use a 2kW Meanwell HEP-2300-55. About 10 amps 240v AC input and 45 amps 48v DC output.

I will probably have to add a second one this winter which will be my first winter in double conversion.

 

[OffGridForGood]

In solar we face many losses to efficiency - starting with the PV panels themselves at 20% - ish oh, and you don't get full rated wattage too often, for too long unless you use dual-axis tracking, but DAT has an energy and complexity cost... just an example of the reality today.
I don't worry too much about the efficiency, I know improvements will come over time. I just focus on systems that work for me, and then plug away at improvements and expansion.