Run house off batteries during the day, no solar.

[Roger440]

Newer battery storage systems are relatively simple, you have a grid connected battery inverter that monitors incoming/outgoing via a CT clamp and sorts out what you want to achieve based on the settings you set. Or use a hybrid inverter that is both PV inverter and battery inverter rolled into one.

However, this comment makes any battery storage irrelevant.

If you are fortunate enough to have a meter that will run backwards if exporting, you have a zero cost or maintenance, profitable energy storage system connected without even doing anything. If your meter spins backwards when you export, you're effectively selling generated power at the same value it cost you to turn the meter forwards.

If that's the case, get some PV up asap and enjoy it before the meter gets changed.

If you do do it, you should probably not submit meter reads, in summer, that suggest the clock has gone backwards though.

This is brilliant! My stubborness might pay off.

Not having a battery even better.

Although, im limited as to what i can export am i not?

Which is another question, how is that export amount controlled? I still dont get that bit?

This has just moved up my list of priorities!

 

[drjim]

If you are using electricity you will use the electricity from your inverters. If you aren't using it all, some will be exported.

 

[Roger440]

It's very simple. Half the panels in series, I'd angle the sets SE/SW, each set connected to the inverter, then inverter wired into mains. DC isolator inbetween the panel string and inverter, AC isolator between supply and inverter.

Found a you tube video, they have surge protectors and meters but ignore those bits and get it wired up pronto!

This, but basically twice?

 

[drjim]

This, but basically twice?

Yes

 

[Roger440]

If you are using electricity you will use the electricity from your inverters. If you aren't using it all, some will be exported.

Yes, i understand that. But the G98 thing limits your export. How is it "limited"?

 

[Roger440]

@Roger440

whats stopping you putting the panels up infront of your unit ?

View attachment 485199

Several reasons. For 6 months of the year, even thats shaded. (those trees are are another several meters taller now!)

Its on the roof, which is very shallow. So exceleent production in mid summer, when i dont need it. Crap the reast of the time. Panels much nearer vertical will, i think, give me a better all round result (meter situation not withstanding)

Most importantly, its 6 meters off the ground, completely inaccesible other that with a cherry picker. Why do that, when i can just plant them on the ground in the field? It cant be an easier. Some bits of timber and its all done.

Or did you mean literally in front of it on the ground? If so, because it will ****. Be right in your eyeline when you look out of the house.

 

[drjim]

If you submit a g98 you are limited to 3600w inverter, more than that is a g99/100 which you preapply for. It's so the DNO knows how much power is likely to appear. If you are using the power you won't export it at all anyway. You could fit a bigger inverter and export more without the application but = naughty.

Once you get to hybrid/battery systems, you have a measuring coil on the incoming supply and the inverter tries to stop export/import whichever way you set it up.

In your scenario you will want to run your workshop dehumidifiers etc, and your solar inverters will feed them instead of it coming in from the mains via your meter.

 

[Roger440]

If you submit a g98 you are limited to 3600w inverter, more than that is a g99/100 which you preapply for. It's so the DNO knows how much power is likely to appear. If you are using the power you won't export it at all anyway. You could fit a bigger inverter and export more without the application but = naughty.

Once you get to hybrid/battery systems, you have a measuring coil on the incoming supply and the inverter tries to stop export/import whichever way you set it up.

In your scenario you will want to run your workshop dehumidifiers etc, and your solar inverters will feed them instead of it coming in from the mains via your meter.

The invertors combined can do 4350w. But i guess, it will never actually produce and export that much?

Dont run the dehumidifiers in summer, unless its particuarly wet.

 

[drjim]

As I suggested split the arrays one pointing SE one SW, then they will hit peak power at different times, you will have the opportunity to use more of the power yourself.

 

[Gareth J]

@Roger440 ,

This is brilliant! My stubborness might pay off.

Not having a battery even better.

Although, im limited as to what i can export am i not?

Which is another question, how is that export amount controlled? I still dont get that bit?

This has just moved up my list of priorities!

You can fit up to 3.68kW of generator capacity to any supply. That's total inverter power, irrelevant of the kW your panels total. To do so, you can install and then inform DNO.

If you want more, and why not, you can apply to DNO with your proposed installation and see if they'll accept it as is or accept it with export limitation. That's very easy to do with modern inverters but probably not the ones you have.

You should probably check it does spin backwards by rigging up a couple panels to an inverter and turning off all house loads to see before getting carried away.

But presuming you do, design a setup should produce up to the your current consumption and put that to the DNO and go from there. Or just start now with what you have and apply for more later.

 

[Gareth J]

As I suggested split the arrays one pointing SE one SW, then they will hit peak power at different times, you will have the opportunity to use more of the power yourself.

What is likely to be produced isn't of interest to DNO, they will let you install only 3.68kW of generator (inverter) capacity. Without pre application.

You can downrate some bigger inverters to max out at 3.68kW so they meet the criterion. E.g. fit 5kWp on a 4kw inverter that's been set to top out at 3.68kW and still be within the rules.

 

[Roger440]

As I suggested split the arrays one pointing SE one SW, then they will hit peak power at different times, you will have the opportunity to use more of the power yourself.

One is 1550w, and the other 2600, so i guess i want to split my panels unequally to roughly match the invertors?

 

[Roger440]

@Roger440 ,

You can fit up to 3.68kW of generator capacity to any supply. That's total inverter power, irrelevant of the kW your panels total. To do so, you can install and then inform DNO.

If you want more, and why not, you can apply to DNO with your proposed installation and see if they'll accept it as is or accept it with export limitation. That's very easy to do with modern inverters but probably not the ones you have.

You should probably check it does spin backwards by rigging up a couple panels to an inverter and turning off all house loads to see before getting carried away.

But presuming you do, design a setup should produce up to the your current consumption and put that to the DNO and go from there. Or just start now with what you have and apply for more later.

Total invertor capacity is 4350w so technically over if i install both.

Understood on checking the meter.

However, i need to install the panels regardless. If the meter wont run backwards, then i might add the forklift or something else.

Id be surprised if they allowed more. Im on spur, off a spur off a spur almost the last house, straight off the 11kv network with my own transformer. Hence why they want to rape me for a three phase supply. Ie, new transformer. But im just guessing.

 

[Gareth J]

One is 1550w, and the other 2600, so i guess i want to split my panels unequally to roughly match the invertors?

Probably, yes. Inverters have an upper limit of installed panel power capacity as well as maximum string voltage. Which must be respected. They correlate with but don't equal the inverter power rating. But you can under supply an inverter.

It's also worth thinking about any shading. If a panel in a string is shaded, it drags the voltage and power output of the entire string down. So, if shading is unavoidable, sometimes you can set up panels so inevitable shading only drags down a portion and not all strings.

Total invertor capacity is 4350w so technically over if i install both.

Understood on checking the meter.

However, i need to install the panels regardless. If the meter wont run backwards, then i might add the forklift or something else.

Id be surprised if they allowed more. Im on spur, off a spur off a spur almost the last house, straight off the 11kv network with my own transformer. Hence why they want to rape me for a three phase supply. Ie, new transformer. But im just guessing.

If you are close to your nearest transformer, with no other generators on the line, it may well be that you can have significantly more than the 3.68. But as you say, just guesswork.

 

[Roger440]

Probably, yes. Inverters have an upper limit of installed panel power capacity as well as maximum string voltage. Which must be respected. They correlate with but don't equal the inverter power rating. But you can under supply an inverter.

It's also worth thinking about any shading. If a panel in a string is shaded, it drags the voltage and power output of the entire string down. So, if shading is unavoidable, sometimes you can set up panels so inevitable shading only drags down a portion and not all strings.


If you are close to your nearest transformer, with no other generators on the line, it may well be that you can have significantly more than the 3.68. But as you say, just guesswork.

Where i intend to put them in the field, they will never be shaded. Completely clear view of the sky.

 

[Roger440]

I see the G98 form requires an installer that is "Installer should be appropriately registered". And wants the installers accreditation/Qualification

Could be problematic for a DIY install????

 

[aesmith]

The proposed installation, two inverters totalling more than 3.68kW, wouldn't be covered by G.98 even with export limitation. The reason being that the limitation isn't perfect so the need to assess the impact of briefly exceeding the limit. For ourselves the SSEN guy explained they look for no more than 1.3% voltage rise at the permitted export, or 2.3% from the total system size.

It depends how legal you want to be. For example legally you should tell the supplier if the meter runs backwards.

 

[Roger440]

The proposed installation, two inverters totalling more than 3.68kW, wouldn't be covered by G.98 even with export limitation. The reason being that the limitation isn't perfect so the need to assess the impact of briefly exceeding the limit. For ourselves the SSEN guy explained they look for no more than 1.3% voltage rise at the permitted export, or 2.3% from the total system size.

It depends how legal you want to be. For example legally you should tell the supplier if the meter runs backwards.

Yes, understand the total of the 2 i have would exceeded the maximum limit. That is a bit of a problem. Its already been suggested i throw away the invertors i have and buy a new one of the correct rating. Decent ones are not cheap though.

I guess my other option is to arrange it so it cant backfeed the grid. But that means more expensive equipment. And then we are back to complicated expensive systems with payback measured in years or decades. Not what i was trying to achieve

 

[addjunkie]

You can get optimiser that basically feed any spare elsewhere, like your hot water and un my case heat store tank. Soin theory nothing should go into the grid. Heres the newer version of what I have.

eddi is the ultimate solar diverter | myenergi UK

eddi is our state-of-the-art solar diverter, designed and manufactured right here in the UK. You can use solar energy to heat your water… for free!

www.myenergi.com

 

[Roger440]

You can get optimiser that basically feed any spare elsewhere, like your hot water and un my case heat store tank. Soin theory nothing should go into the grid. Heres the newer version of what I have.

eddi is the ultimate solar diverter | myenergi UK

eddi is our state-of-the-art solar diverter, designed and manufactured right here in the UK. You can use solar energy to heat your water… for free!

www.myenergi.com

Hmmm. What does it actually do? Their website has a lot of words on it, but no explanation of what it actually does, or even how it does it.

On the website it says "Solar PV owners without an eddi waste large amounts of their self-generated energy by giving any unused electricity freely, or cheaply back to the grid"

How can that possibly be true? The electricity doesnt decide where to go. If ive got 3 kw coming in from my panels, and im using 4kw of "stuff" then im using it all. Conversley if im making 3kw from my panels, but im not using anything, where can the power go other than into the grid. Unless you have storage, i cant see what problem its solving

Sorry, might be being dumb?