To me this seems complicated - choosing solar PV

[MikeSharp01]

It is time to fit the solar system and the interplay between choices one could make is interesting to say the least. We have one fixed point - the solar array 16x430 panels from Eurener. The rest is now to be decided and that leads me to four main questions perhaps 3 if you combine the 2nd and 4th with a few more supplementary ones on the side. Here is a picture:

 

A. What size inverter I assumed bigger than 6kW but I am being told that 6kW will be OK.

B. Must I choose batteries now - economics really yes we can afford them but the value does not quite seem to have topped out yet? This is somewhat mixed up with D below as well.

C. Our DNO says they will allow up to 5kW after limiting so given we have, in theory, 6.9kW we will need a limiting inverter but as yet I have not found a hybrid that says it does limiting out of the box.

D. Once you get a hybrid inverter what technologies are available for charging batteries is it all proprietary - IE limiting choice of batteries to those from the inverter supplier or generic, which I suspect it can't be wholly be but maybe it can.

[SteamyTea]

So a 6.88 kW_p install.

The _p just means peak power.

Now you will very really hit peak power, it relies on the sun being in the right place, the sky clear, the temperature optimal, and economically somewhere dump the power to.

Most inverters can handle quite a bit of overpower, 20% is not unusual. The datasheet will tell you.

So you could probably safely get a 6 kW inverter.

 

As you have a 5 kW limit, you need to find an inverter that can charge batteries on the DC side or you may be missing out on opportunities to charge i.e. when you are generating more than 5 kW and the inverter is limiting the overall output.

 

As for batteries, my view is they are a nice toy, but will cost you money. Water storage via a diverter is worthwhile though.

 

So bearing that in mind, buy a cheaper, bog standard, 6 kW inverter, fit a diverter, forget the batteries, and therefore the hybrid inverter and wait until the market for home generation matures.

 

But get your students to make a decent, open source, energy and temperature logger, the data will tell you much more that a salesman/installer can.

[MikeSharp01]

On 30/04/2024 at 16:39, SteamyTea said:

open source, energy and temperature logger

I am hopeful!

 

[SteamyTea]

1 minute ago, MikeSharp01 said:

I am hopeful!

 

I am sure there would be lots of useful ideas to incorporate from people on here.

[JohnMo]

Inverters, just watch max amps and voltage as big panels will exclude a lot of normal inverters maybe not hybrid inverters choices.  5.5 to 6kW will be fine, most the time will be well below that anyway.

 

B. No, you can always AC coupled, which is what I did, a little efficiency loss but that's ok. Most hybrid inverters will only do one circuit in black out so check before purchase. My AC coupled runs the whole house up to 6kW continuous load.

 

C. Our GivEnergy all in one is settable to any export limit you want.

 

 

 

 

[Dillsue]

For export limitation, G100 requires the limitation to be password protected by a factory or installer password that the user shouldn't have! If you go for an inverter over your DNOs 5kw limit you'll need one with a G100 cert and professionally installed to comply. No idea if your DNO is bothered with such things?? Our DNO said if we went for export limitation they'd want to witness it and charge several hundred £ for the privilege

 

If you go with a 5kw inverter with a G99 cert that should limit to 5kw but check the cert. I don't know about other manufacturers but Solaredge allow up to 200% DC input of the inverters rated AC output so an SE5000H can have 10kw of panels connected