Mastervolt Soladin 600 inverter questions

[siliconskum]

As per another thread on this forum, I'm trying a part-DIY 600W solar PV install, and I'm going to use the Mastervolt 600 inverter. I'm finding LOTS of conflicting information regarding what is / not allowed regarding the AC connection. The inverter is fitted with a UK 3 pin plug and is supposed to be pluged directly into a socket - I understand this does not comply to the wiring regs, so no issues there.

However I have been told by others on other forums, that:

1. It must be connected via an AC disconnect, RCBO and be wired directly to the CU on it's own circuit.

2. It can be connected via a fused, switched spur from an existing socket ring main. Fitted with a 3 Amp fuse.

3 As above but with a single CU fitted with an RCBO, instead of spur, then via socket ring to CU.

4. AC disconnect, RCD and connected to fused spur from socket ring.

Plus a number of people who claim it's fine just plugged in via a socket and won't accept any other view...


Ok, so I'm lost - what is reccomended setup, and what is the minimum setup that is required to be legal? I would like to know before I start buying parts and wasting money on something I can't use / don't need. It's being wired up by a qualified electrician, but I'm supplying parts and fitting panels to roof.


Also a side question, would I be better adding another panel and running the inverter at it's limit of 700W (720w with my panels) for better winter use (west facing), or keep it at the manufacturer reccomended 600W? Inverter has a max output of 525W regardless of higher input.

Thanks.

SS

 

[Earthstore]

You need an electrician that understands PV.
But to cover some of your points, you can not connect into a ring main in any way shape of form, you can not use a 3 pin plug, also you can not install on a shared RCD.

As to the amount of panels, this all depends on the voltage range parameters of the inverter.
It should have a start up voltage and a maximum voltage, IE if the maximum voltage is 100V and you have 4x30V panels then your voltage would be 120V which is too high for the inverter.
I hope this helps.

 

[siliconskum]

Yeah, that pretty much confirms what I allready suspected. Cheers.

Agreed about the PV savvy electrician - but that is proving to be not so easy at the moment. A small non FITs install seems to be almost impossible to get done, either companies are not interested or qualified sparkys don't want to touch it. I found one national installer that would install a 710Wp FITs system with mastervolt inverter, but they wanted the best part of £5,5K. DIY allows me to get it installed for around £2,5K. Thats a big difference in price! At least at £2,5K I have a chance to recover my costs within my lifetime.
I can't affort £5K to £10K for a PV install, and I won't be living in this house long enough to see a payback.

Unless something changes, when the FITs end it seems like it will be technically impossible to get solar PV installed. I don't really want to wait several more years until I can install a small cheap system without FITs. And by then, god knows what regulations will be in place that prevent such an install... I only need it to help reduce the running costs of a couple of computer servers. They are my only large load, and runs 24/7.

I'm starting to think I will have to go back to my original idea, a grid-fallback system using a software modifed computer UPS, not as efficient or simple, but at least I can do it with out so many regulations and red tape getting in the way. It's designed for that use, and has a generator / battery bank input on the DC side, so all I have to do is connect the panels (with disconnect and DC MCB / fuses) and add a battery bank. Bttery bank is used to stablise the UPS, not for storing power to use at night.

It's a cludge, but at least I can do it legally. It's technically a standalone PV system.

SS

 

[Earthstore]

Just a tiny question, how much power do these computers use?
Just at a very rough calculation, this PV system may save you around £50 a year on your electricity bill, at a cost of c£2500, that's a long payback....
Why not look at voltage optimization instead, 10%+ savings on your electricity bill...

 

[siliconskum]

After a few recent upgrades and a few power management tweaks, I managed to wittle it down to 300 watts average, 350W peak. Thats down from about 480W. That's not including monitors and peripherals, NAS storage, networking gear etc. full load would be around 550Wp and around 400W average. As you can see, anything I can shave off that will be helpfull. I halved my electricity bill in tha last 12 months with other measures like LED lighting, but I cant shave much more off.


That voltage optimization is only usefull for devices that don't use switch mode power supplies like computers - they will adjust to pull the same amount of power regardless of the voltage. Most SMPS can run from anything between 265V down to 60V and still spit out the same wattage.

SS