That's a great resource and I've got a lot of information from it, looks like you're quite a pro in the solar world @Chrisd in terms of basic connectivity, this is a good illustration for a non battery system.
Finished the frame and loosely fitted the panels to check for fit. Today's job is to fit the frame to the roof before it gets too hot, lay the cables and hopefully fit the panels this evening when it gets a bit cooler
Hmm, I don't know if its an optical illusion or a lens flare, but isn't the sun in that pic behind your panels? If that's taken in the evening then it means your panels are currently facing ~east. I can't see the rest of your garden so I don't know what foliage there is to stop you pointing them more southerly. If any of your panels get shaded during the day, and they're wired up in serial, then the whole output will drop significantly.
You're right, I built it in the garden. It's going up on a flat roof pointing due south. I'm wiring them in 2 strings of 4 panels as the sun will set over the first string in the evening
That explains it. One more question. Is the single string voltage above the minimum required to turn the inverter on? I ask because 4 panels will have a voltage maybe ~150v (depending on make/model/type) and some inverters need more than that to start up.
The open circuit voltage of each panel is 35V (at NOCYT, so I'm looking at 140V per string. The inverter startup voltage is 100V, is that a bit tight do you think?
Nah you should be good. With solar panels the voltage output doesn't vary that much, you'll find as soon as it's daylight the panels will be able to start up the inverter. The amount of sun has more effect on the amount of current that will flow.
how are you fixing them? we just ballasted ours with sand bags so they can be easily removed/ moved in future if needed. also means you don't need to damage the roof..
Have you done wind load calculations? It could be that in a 70mph northerly wind, the solar panels will become busy flicking sandbags off the roof on their path to self destruction.. Might be worth using ropes as well to stop them flipping over..tied to something solid.
Wind tunnel tested for pressure and suction with TÜV certification, and ballast calculated in line with Eurocode 1 (EN 1991).
They're on a frame on top of an outbuilding, I'm screwing the frame to the roof joists through the steel sheets using self sealing/drilling bolts. They're sheltered at the back (north) by a row of conifers and to the west by another roof so it's just south which is head on or east which sholud pass through and dissipate.
Mr Moose is up ( an old Fawlty Towers joke for those of you too young to know), next job is running the DC cables and fitting the DC and AC isolators together with the inverter and meter. Then it's down to the Sparky.
Dont forget the ends of the DC cables off series connected panels are just as lethal as mains if the cells are in series : more so because its DC so you cant drop it. Seems stupid people can wire up the DC but arent allowed to do the mains..
