SteamyTea

Do a time series based cost analysis. Taking Thames water as an example, water and waste currently costs 2.28/m3 Using an inflation rate of 2%, it will take 64 years to get to £8/m3. I currently pay, down in the South West, a gnats over that at £8.083.

That is about 1Wp a year on a 250Wp module. What many manufactures actually do is select the best batches of modules, say the ones that are actually rated at 265Wp on the standard tests, label them as 250Wp, then charge a premium for them. This leaves you with a 238.5Wp module, which is performing at 95.4% of the what you thought was a 250Wp module. Trouble with this is that for a few years, your system will seem to perform better than expected, then eventually drop off. So you may be better off just looking at slightly better performing modules, rather than ones with a warranty. Some of the 'cheap Chinese' modules are identical to the more expensive 'USA or EU' made ones. Thing is, they are often the same product, from the same factories, made with the same materials, on the same machinery, by the same people etc etc. Just the testing and labelling is what sets the output, not the quality, or price, of the product.

Being able to easily add to a system is useful. Stecca used to do an inverter system like this. You bought a 2 kW inverter that had all the controls in it, then just kept adding extra 2 kW basic inverters to it. And it kicked in once the module string was generating 80V, which meant it actually generated more kWh than a comparable SMA system.

Realistically it is not that often that a PV system delivers at full power. It is easy to get carried away with the weather we have been having the last couple of months, but think back to last October, November, December and January.

Amy be worth reading though this short document as it gives some general details, and where to find more indepth stuff: http://www.inbalance-energy.co.uk/further_reading_books/pv_installers/Guide to the installation of PV systems_2nd Edition.pdf It is a decade now since I was involved in PV, but as far as I can remember, and what I have heard from some installers, two things have changed. Inverters are not allowed in lofts anymore and the system capacity is set by total module capacity. But as usual, there is probably more to it this this, the so called 'gotchas'. One thing that is interesting is that inverters need to have isolators on both the DC and AC sides. Not sure how that is implemented with micro-inverters. Be a lot of switches.

In reality yes, but I think the DNO sets the limit on module capacity, or people would fit a 16A limit inverter, then attach 5 or 5.5 kW of modules to it. This would cause the DNO problems, regardless of what the technical limit. One way to check is to ask the DNO if it is ok to fit a diesel generator to their lines. I believe this is one of the reasons that CHP is limited on the electrical generation capacity, to do with the hour running.

Does it shut the inverter down totally, or limit the voltage, which reduces the headline efficiency figure, but not really a real issue.

Well it will be 16A ~3.7 kW But that is governed by total module size, not inverter trickery (usually, there are always exceptions). So decide what you can do with an extra 2 kW as an off grid system i.e. dedicated water heating/sewage plant running/battery storage.

Split it into 3 sections and fit 3 separate 4kW inverters. Then switch of the inverters you don't need. Actually you may want to fit 3 3kW inverters to get better efficiency.

kW k for thousand. W for watt.

Not the numbers, it is the units.

Always worries me when I see things like this Heat Coil 30 kw And then a second time Output: 30 kw

I have worked for people that like to make a simple job difficult too.

Could have been worse. Could have dreamt about Sisyphus.

So very little floor losses then.