Solar power requirement

[daveydiesel1]

Hi all. Just ponderin in my head. How much power is required to run a 10 swing over parlour with augers and water heaters and bulk tanks? How many solar panels would it take to run this without havin to buy electric and how much would a set up like this cost? Also is there any government help or grant schemes?

 

[upnortheast]

Just doesn`t add up. 1st - the cost of a solar installation only added up when the FIT paid 12p kw or more. Now there is none
2nd - solar only gives decent output in summer & between 9am & 4pm when the sun is shining.
So for an essential job like milking it would be a disaster especially as your milking times would be outside that timescale.
Normal arrangement is the solar is connected into your mains supply after your meter. Because the inverters push out the power at a slightly higher pressure (volts) than the mains that power is used 1st if available. So solar can reduce your mains cost but is not viable as a stand alone power source. Technology may change that some time in the future

 

[daveydiesel1]

So big battery to store the power wouldnt be viable then either

 

[upnortheast]

Only if you have won lotto.

 

[upnortheast]

Graph here of monthly solar output from a 4 kw installation
Lets assume your dairy needs 300 kw a day you can do the sums

 

[daveydiesel1]

So how much would a 4kw cost?

 

[upnortheast]

Ball park £1000 / KW. But as you can see from the graph that will give bugger all of your needs

 

[chickens and wheat]

Solar suits such as broiler farming much better. The demand for ventilation rises with the sun as does solar production.
Assuming a low level of export the efficiency/price of modern panels/inverters means my new system (no fit) has the same payback as one I installed in 2013 with fit.
Not quite correct as 2013 was 10kw install new one is 100kw so there are some scale price adjustments to be allowed for.

New system finds 20% more power per panel than 2013 system.

So basically if you have a decent power draw during the best part of the day, solar stacks up well, as a way of protecting yourself from future elec tarrif rises as much as anything else

 

[upnortheast]

Interesting that your new panels produce 20% more
Agreed ventilation / refridgeration are ideal match for solar
Milking at 5am & 4pm not so,

 

[chickens and wheat]

20% so far, winter only. Summer might change things?
New panels had been up a couple of months before I got the export limiter off (waiting for transformer upgrade) and true comparisons could begin. Old panels washed before then. So they should all be a similar amount 'dirty'

Transformer upgrade costs not included in payback. That spoils the figures somewhat, and solar wasn't the only reason to upgrade.
Mains cabling for 100kw not included either as it was fortunately pre installed , not a small price to consider in some set ups.
So it's not simple to calculate if solar is sensible or not.

My gshp installer had a data logger on my supply for several months before installing that. Also we got hold of the half hourly data from npower after the gshp. All this data along with existing solar production data, showed solar was a good choice here.
Having such research also helped negotiate good bank loan terms.

 

[upnortheast]

Done your homework very thoughouly. The maths arn`t too difficult but I hear of folk who take the word of the panel salesman as gospel & proceed on the back of that.
Never a good idea IMO

 

[chickens and wheat]

Solar install wasn't in question,the calculation was to discover how many KW to install,. We ended up getting as much as we could on our connection.
Anymore would require export limitation.