How much can I practically/legally DIY, and other newb questions

[Deanforest]

The main problem with the DIY stuff is if you intend to feed into the grid to claim a tariff. There are two points. One is that you have to know enough to make sure that the phases from your inverter lock with the grid phases before a switch over takes place. A failure here could result in a spectacular meltdown in your equipment at the least, but at worst you could trip out the supply to your area. Modern inverters do this automatically, but it’s not just a simple switchover.
The second point concerns the supply you are feeding into. All ac in the U.K. is 3 phase, but single phases of this 3 phase system are fed to blocks of housing, in such a way that the phases are more or less equally loaded. If a group of houses start feeding back into the system this can seriously unbalance the 3 phase system, which is why you need to apply to do this, and why it sometimes takes a while to get an answer, as the effect on the whole local distribution has to be looked at.
There is nothing wrong with doing the basic wiring and component mounting as a diy’er, but you need an accredited professional to do the commissioning, if you can find one that is happy to check your work and sign it off.
It’s a whole lot easier if you are off grid, and in theory, you could get paid , at a lower tariff, for what you generate, at least on paper. However, I never found anyone of my local suppliers who had the expertise to understand how this would work, particularly to differentiate between solar, and emergency charging from the generator backup. Easy in principal, but no approved dc meter available at the time.

[nowty]

The main problem with the DIY stuff is if you intend to feed into the grid to claim a tariff. There are two points. One is that you have to know enough to make sure that the phases from your inverter lock with the grid phases before a switch over takes place. A failure here could result in a spectacular meltdown in your equipment at the least, but at worst you could trip out the supply to your area. Modern inverters do this automatically, but it’s not just a simple switchover.
The second point concerns the supply you are feeding into. All ac in the U.K. is 3 phase, but single phases of this 3 phase system are fed to blocks of housing, in such a way that the phases are more or less equally loaded. If a group of houses start feeding back into the system this can seriously unbalance the 3 phase system, which is why you need to apply to do this, and why it sometimes takes a while to get an answer, as the effect on the whole local distribution has to be looked at.
There is nothing wrong with doing the basic wiring and component mounting as a diy’er, but you need an accredited professional to do the commissioning, if you can find one that is happy to check your work and sign it off.
It’s a whole lot easier if you are off grid, and in theory, you could get paid , at a lower tariff, for what you generate, at least on paper. However, I never found anyone of my local suppliers who had the expertise to understand how this would work, particularly to differentiate between solar, and emergency charging from the generator backup. Easy in principal, but no approved dc meter available at the time.

Most folk are on a single phase system and a G98 install up to 3.68kW system on a single phase is allowed as a fit first and notify to DNO after. Only multiple G98 installations in a local area and G99 applications are an application first, before any installation can go ahead.

Many on here have done the installation, commissiong and the DNO notification perfectly legal themselves. The only thing that generally needs to be done with a professional is the Part P electrical work.

[Oldgreybeard]

Many on here have done the installation, commissiong and the DNO notification perfectly legal themselves. The only thing that generally needs to be done with a professional is the Part P electrical work.

This is exactly what I did. I had a Part P electrician test and sign off the cables run in to the outbuilding where I installed the battery system, with those cables terminated in four pole isolator switch. I could then perfectly legally do everything else, as I was just working on an existing circuit. IIRC I think I paid the guy about £80 to just connect the cables at either end and test them. Money for old rope, really, as it only took him about half an hour.

[dangermouse]

Finally, have found a roofer who knows about solar panels - he works for a solar installation firm but is willing to do side jobs, for a reasonable price.

So I'm looking at getting 8 x 295W Perlight panels as sold by Bimble here. Giving a peak of 2360W which perfectly matches the input rating (2400W) of one of the PV inputs on my inverter. Leaving me another inverter PV input free for future expansion. I've got a small roof, and putting these panels in landscape mode 2 across 4 down will give me about 60cm border around the panels, which sounds good to me.

I could potentially squeeze 10 panels onto the roof but the numbers don't really add up. Either I'd have more power than one inverter input can handle, so at peak times I'd just be wasting power, or I'd have to split the panels into 2 strings and use both inputs, in which case the voltage from the panels is getting a bit close to the inverter's minimum input voltage. I think I'd rather keep an input free and have the option of panels on the garage roof at a later time.

The roofer is recommending solar limpets - anyone got an opinion (good or bad) on these?

So far my shopping list consists of:
Solar limpets
Mounting rails
6mm DC cable
MC4 connectors (I assume all panels use these?)
Some sort of isolator - I was think of using another Mersen fused disconnect, the same as I bought to isolate the batteries.

Have I missed anything?

[Oldgreybeard]

Some sort of isolator - I was think of using another Mersen fused disconnect, the same as I bought to isolate the batteries.

Standard way to isolate DC from panels is one of these: https://www.cef.co.uk/catalogue/product ... lator-ip65

There are higher rated ones available if your panels can deliver a higher current.

They are rated to handle the relative high, and potentially more dangerous than AC, voltage from the panels, with no exposed parts. The Mersen switch fuses would be potentially dangerous, I think, as they don't protect the live DC terminals at all well.

[dangermouse]

Oh thanks, I've got a big rotary isolator like that (but an AC version) between the inverter and CU, I'll get the matching pair

Panels are max 10A so that one would be fine.

[sharpener]

Finally, have found a roofer who knows about solar panels - he works for a solar installation firm but is willing to do side jobs, for a reasonable price.

So I'm looking at getting 8 x 295W Perlight panels as sold by Bimble here. Giving a peak of 2360W which perfectly matches the input rating (2400W) of one of the PV inputs on my inverter. Leaving me another inverter PV input free for future expansion. I've got a small roof, and putting these panels in landscape mode 2 across 4 down will give me about 60cm border around the panels, which sounds good to me.

I could potentially squeeze 10 panels onto the roof but the numbers don't really add up. Either I'd have more power than one inverter input can handle, so at peak times I'd just be wasting power, or I'd have to split the panels into 2 strings and use both inputs, in which case the voltage from the panels is getting a bit close to the inverter's minimum input voltage. I think I'd rather keep an input free and have the option of panels on the garage roof at a later time.

The roofer is recommending solar limpets - anyone got an opinion (good or bad) on these?

So far my shopping list consists of:
Solar limpets
Mounting rails
6mm DC cable
MC4 connectors (I assume all panels use these?)
Some sort of isolator - I was think of using another Mersen fused disconnect, the same as I bought to isolate the batteries.

Have I missed anything?

If you have the room it might be worth getting the 10 panels if the inverter will safely restrict the input power - worth checking this, not all will. In the UK 125% oversize is good because acheiving full output is comparatively rare and it will give you more output under typical winter conditions when you most need it. Victron say the amount of curtailment is only 1% of total generation so worth it overall.

Don't much fancy solar limpets, they need accurate location of the joists, require drilling through the tiles/slates and rely on mastic rather than gaskets for sealing. There is an earlier thread on them somewhere. But I guess if your man prefers them as he is used to them you may not have much option.

What is your roof covering? I think they were developed for tiles and may be better on them than on slates.

Also I was told they will only sell them to people who have undergone their supervised training regime, so after a lot of back-and-forth Callidus could not supply them for my installation kit. They are also boxed in 25s IIRC, I didn't find anyone else who stocked them or who would split boxes.

[sharpener]

Finally, have found a roofer who knows about solar panels - he works for a solar installation firm but is willing to do side jobs, for a reasonable price.

So I'm looking at getting 8 x 295W Perlight panels as sold by Bimble here. Giving a peak of 2360W which perfectly matches the input rating (2400W) of one of the PV inputs on my inverter. Leaving me another inverter PV input free for future expansion. I've got a small roof, and putting these panels in landscape mode 2 across 4 down will give me about 60cm border around the panels, which sounds good to me.

I could potentially squeeze 10 panels onto the roof but the numbers don't really add up. Either I'd have more power than one inverter input can handle, so at peak times I'd just be wasting power, or I'd have to split the panels into 2 strings and use both inputs, in which case the voltage from the panels is getting a bit close to the inverter's minimum input voltage. I think I'd rather keep an input free and have the option of panels on the garage roof at a later time.

The roofer is recommending solar limpets - anyone got an opinion (good or bad) on these?

So far my shopping list consists of:
Solar limpets
Mounting rails
6mm DC cable
MC4 connectors (I assume all panels use these?)
Some sort of isolator - I was think of using another Mersen fused disconnect, the same as I bought to isolate the batteries.

Have I missed anything?

If you have the room it might be worth getting the 10 panels if the inverter will safely restrict the input power - worth checking this, not all will. In the UK 125% oversize is good because acheiving full output is comparatively rare and it will give you more output under typical winter conditions when you most need it. Victron say the amount of curtailment is only 1% of total generation so worth it overall.

Don't much fancy solar limpets, they need accurate location of the joists, require drilling through the tiles/slates and rely on mastic rather than gaskets for sealing. There is an earlier thread on them somewhere. But I guess if your man prefers them as he is used to them you may not have much option.

What is your roof covering? I think they were developed for tiles and may be better on them than on slates.

Also I was told they will only sell them to people who have undergone their supervised training regime, so after a lot of back-and-forth Callidus could not supply them for my installation kit. They are also boxed in 25s IIRC, I didn't find anyone (apart from Solar Limpets themselves) who stocked them or who would split boxes.

[AE-NMidlands]

I could potentially squeeze 10 panels onto the roof but the numbers don't really add up. Either I'd have more power than one inverter input can handle, so at peak times I'd just be wasting power,

I am watching these threads ready for when I can start, so my question is only a query rather than sound advice:

I have got the impression (from our Pioneers) that as the installation costs are more-or-less fixed you might as well go for everything you can fit in or afford from day 1. Don't worry about summer surplus, i.e. the roof panels stalling when they get up too what the inverter can handle, because the greater your kWp the further into autumn will you cover your daily consumption. Ditto an earlier day for 100% self-generated in spring?

No?

[Fintray]

I could potentially squeeze 10 panels onto the roof but the numbers don't really add up. Either I'd have more power than one inverter input can handle, so at peak times I'd just be wasting power,

I am watching these threads ready for when I can start, so my question is only a query rather than sound advice:

I have got the impression (from our Pioneers) that as the installation costs are more-or-less fixed you might as well go for everything you can fit in or afford from day 1. Don't worry about summer surplus, i.e. the roof panels stalling when they get up too what the inverter can handle, because the greater your kWp the further into autumn will you cover your daily consumption. Ditto an earlier day for 100% self-generated in spring?

No?

Definitely!