Design task

R32 · Feb 5, 2012

Taking into account my limited knowledge is there anybody out there that would help me understand a bit more about PV installations?

The task is detailed below and he said it shouldn't really take that long

A PV grid tied system designed as a non-critical standalone facility with a requirement of **Wh/day. Determine PV size and battery storage requirement assuming a typical insolation for ** at latitude of *** north.

Detail the likely performance for the insolation in question

Even if you don't have the time to help me with the whole question any pointers in the right direction would be greatly appreciated.
Regards

sharpener · Feb 6, 2012

Try the various calculators at PV potential estimation utility. You need to decide first whether the **** is Newcastle-upon-Tyne or S. Denmark.

You say it is non-critical, what probability will "he" accept that the battery will run out before the next sunny day? I do not have data for **, but over the last two months the longest period without any appreciable PV generation has been 5 days, do you have to cover a gap like this?

Some more background on insolation vs day and latititude available here: https://www.builtsmartresources.com/educational-resources.html

Try googling insolation statistics.

R32 · Feb 6, 2012

I was under the impression that grid tied meant when not enough power is generated you draw power from the national grid? And it is for Newcastle.

sharpener · Feb 7, 2012

As people have said in reply to your other thread, to get a more detailed answer you need to obtain/give a better definition of the requirement. Normally speaking a system is either grid-tied (i.e. it can export or import depending on how sunny it is) or it's standalone i.e. you need battery backup when the sun isn't shining. Confusingly standalone can also mean the opposite of roof-mounted and that seems now to be the meaning in the question you have been set.

The term "balance of plant" is familiar in base-load power stations (as meaning everything except the main turbogenerator, so transformers, switchgear, feedwater pumps etc). However it is not widely used in the small-scale solar PV industry which is perhaps why you have not got as clear an answer as you might have wished. As others have said an ordinary *kW grid-tied system would cost at least £7500 complete and installed, there are other threads here already with further cost trend info if you want it. For more on battery backup systems look up e.g. SMA Sunny Backup or Steca SolSafe. They tend to be expensive because of the cost of the extra inverter and the long-life deep-discharge batteries, and the special changeover relay needed to switch the full load from grid to inverter in milliseconds.

BTW you will not get far in life if you get shirty when people are trying to help you, on this forum there is no charge for pressing the Thanks button occasionally.

HTH