Grid tie - limiter?

Spikeuk

New Member
Joined
Nov 23, 2021
Messages
13
Hi Guys,
Based in UK - I'm looking to fitting a solar array myself, to bring down electricity costs.
Im a complete noob so please comment / correct me / advise - would be greatly appreciated!

I run a computer which is using 1200w power 24/7 I would like to bring electric costs down a bit using PV.

It doesnt have to produce 1200w constantly but just to bring down costs. I don't want to export back to the grid otherwise I have to mess about with telling power company etc- and then only getting paid 5p while still paying 30p per kwh.

Off grid - With a off grid system I need to buy some expensive large batteries Lifepo4- which may or may not fail within a couple of years if im cycling them low regularly... from what I can tell this seems really expensive and may not save much money due to battery costs.

Grid tie - I don't want to export, I want to use what I produce - I realised you can get grid tied inverters which have 'limiters' - from what I have read do not feed any power back to the grid, theres a C clamp to go onto the mains cable on your house meter which monitors power usage, the inverter then provides as power as possible to meet the demand reading from the meter cable - this way you are using PV power and grid power at the same time without exporting - is this correct? this sounds ideal as I can use power from PV during day when panels are active as its produced and do not need any batteries?, any shortfalls in PV are substituted by grid power? i.e. 700w pv 400w grid for my 1200w load?

Do I need to inform power company if its grid tie with limiter as i am not feeding back? or just get qualified elec to install.

Also Im looking to install system garage roof, approx 50m from my main meter where the 'C' clamp needs to go for the limiter. (long cable length for c clamp to inverter -not accurate readings)
Could I not just use the C clamp on the plug socket cable directly where the 1200w load is pulled from and the PV will try to output upto 1200w?

I have smart meter fitted, SMETS2 i think is the type, I read somewhere possible problems with smart meters?

Any advice would be greatly appreciated!

Thanks guys!!!
 

sunshine_eggo

Happy Breffast!
Joined
Oct 26, 2021
Messages
3,935
Location
USA
Hi Guys,
Based in UK - I'm looking to fitting a solar array myself, to bring down electricity costs.
Im a complete noob so please comment / correct me / advise - would be greatly appreciated!

I run a computer which is using 1200w power 24/7 I would like to bring electric costs down a bit using PV.

It doesnt have to produce 1200w constantly but just to bring down costs. I don't want to export back to the grid otherwise I have to mess about with telling power company etc- and then only getting paid 5p while still paying 30p per kwh.

Off grid - With a off grid system I need to buy some expensive large batteries Lifepo4- which may or may not fail within a couple of years if im cycling them low regularly... from what I can tell this seems really expensive and may not save much money due to battery costs.

Grid tie - I don't want to export, I want to use what I produce - I realised you can get grid tied inverters which have 'limiters' - from what I have read do not feed any power back to the grid, theres a C clamp to go onto the mains cable on your house meter which monitors power usage, the inverter then provides as power as possible to meet the demand reading from the meter cable - this way you are using PV power and grid power at the same time without exporting - is this correct? this sounds ideal as I can use power from PV during day when panels are active as its produced and do not need any batteries?, any shortfalls in PV are substituted by grid power? i.e. 700w pv 400w grid for my 1200w load?

Do I need to inform power company if its grid tie with limiter as i am not feeding back? or just get qualified elec to install.

You need to check with your local authority.

Also Im looking to install system garage roof, approx 50m from my main meter where the 'C' clamp needs to go for the limiter. (long cable length for c clamp to inverter -not accurate readings)
Could I not just use the C clamp on the plug socket cable directly where the 1200w load is pulled from and the PV will try to output upto 1200w?

In the U.S. there are additional regulations concerning roof mounted panels relating primarily to fire safety, i.e., if firefighters have to be on your roof, the system complies with those safety measures. I suspect there is something comparable in the U.K. Check with your local authority.

I have smart meter fitted, SMETS2 i think is the type, I read somewhere possible problems with smart meters?

I would expect that's the case with grid-tie and feedback. A limiter might avoid those issues.

Just guesses on my part.
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
922
Location
Hungary - EU
Hi Guys,
Based in UK - I'm looking to fitting a solar array myself, to bring down electricity costs.
Im a complete noob so please comment / correct me / advise - would be greatly appreciated!

I run a computer which is using 1200w power 24/7 I would like to bring electric costs down a bit using PV.

It doesnt have to produce 1200w constantly but just to bring down costs. I don't want to export back to the grid otherwise I have to mess about with telling power company etc- and then only getting paid 5p while still paying 30p per kwh.

Off grid - With a off grid system I need to buy some expensive large batteries Lifepo4- which may or may not fail within a couple of years if im cycling them low regularly... from what I can tell this seems really expensive and may not save much money due to battery costs.

Grid tie - I don't want to export, I want to use what I produce - I realised you can get grid tied inverters which have 'limiters' - from what I have read do not feed any power back to the grid, theres a C clamp to go onto the mains cable on your house meter which monitors power usage, the inverter then provides as power as possible to meet the demand reading from the meter cable - this way you are using PV power and grid power at the same time without exporting - is this correct? this sounds ideal as I can use power from PV during day when panels are active as its produced and do not need any batteries?, any shortfalls in PV are substituted by grid power? i.e. 700w pv 400w grid for my 1200w load?

Do I need to inform power company if its grid tie with limiter as i am not feeding back? or just get qualified elec to install.

Also Im looking to install system garage roof, approx 50m from my main meter where the 'C' clamp needs to go for the limiter. (long cable length for c clamp to inverter -not accurate readings)
Could I not just use the C clamp on the plug socket cable directly where the 1200w load is pulled from and the PV will try to output upto 1200w?

I have smart meter fitted, SMETS2 i think is the type, I read somewhere possible problems with smart meters?

Any advice would be greatly appreciated!

Thanks guys!!!

The easiest way is with an off-grid (with grid support) inverter.
Just put it on your main, or just use it for a separated part.
It does not need battery (optional). You can add to it to make it an UPS, but it works without it.
So the grid comes in to the inverter (AC_in), you have the 1200W load (AC_out), solar panels produce 800W (MPPT_in) ... then you use only 400W from grid and all the 800W from solar.
The main/biggest cost for this system will be the solar panels.

off-grid.jpg
 

bruce_loco

New Member
Joined
Mar 30, 2022
Messages
32
Hi Guys,
Based in UK - I'm looking to fitting a solar array myself, to bring down electricity costs.
Im a complete noob so please comment / correct me / advise - would be greatly appreciated!

I run a computer which is using 1200w power 24/7 I would like to bring electric costs down a bit using PV.

It doesnt have to produce 1200w constantly but just to bring down costs. I don't want to export back to the grid otherwise I have to mess about with telling power company etc- and then only getting paid 5p while still paying 30p per kwh.

Off grid - With a off grid system I need to buy some expensive large batteries Lifepo4- which may or may not fail within a couple of years if im cycling them low regularly... from what I can tell this seems really expensive and may not save much money due to battery costs.

Grid tie - I don't want to export, I want to use what I produce - I realised you can get grid tied inverters which have 'limiters' - from what I have read do not feed any power back to the grid, theres a C clamp to go onto the mains cable on your house meter which monitors power usage, the inverter then provides as power as possible to meet the demand reading from the meter cable - this way you are using PV power and grid power at the same time without exporting - is this correct? this sounds ideal as I can use power from PV during day when panels are active as its produced and do not need any batteries?, any shortfalls in PV are substituted by grid power? i.e. 700w pv 400w grid for my 1200w load?

Do I need to inform power company if its grid tie with limiter as i am not feeding back? or just get qualified elec to install.

Also Im looking to install system garage roof, approx 50m from my main meter where the 'C' clamp needs to go for the limiter. (long cable length for c clamp to inverter -not accurate readings)
Could I not just use the C clamp on the plug socket cable directly where the 1200w load is pulled from and the PV will try to output upto 1200w?

I have smart meter fitted, SMETS2 i think is the type, I read somewhere possible problems with smart meters?

Any advice would be greatly appreciated!

Thanks guys!!!
I am on the same boat.

At 3.5p per KW, I will not waste thousands of pounds in a certification and professional installation.
From what I heard, if you don't grid tie, you don't need DNO permission.
The inverter becomes an appliance.
I am getting the https://voltaconsolar.com/off-grid/48v-off-grid-inverter-charger/conversol-max-8kw-off-grid.html
This is the MPPSolar 8048Max without the import hassle.
Keep in mind that the Max charging current on the MPPT is 80A compared to the MPPSolar at 120.

It means that when you have solar energy you will get something running, but when you are out, it goes off at night and pulls from the mains.
keep in mind a small battery set like a seplos at 16kw costs around 400£(bms in box kit) + 2000£(16xEve's 304Ah) -> more power than a tesla power wall at 2.5k
But this is overkill, mostly at night I spend around 2-3kw(will change as I got a heap pump).
 
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