Go, no go?

[del]

Go, no go? 

Hello from South Essex, England, and a first post.

Having added an extension to the house, a mid terrace, Edwardian, brick built, two storey, east west facing roof, we had to cut the mains power to the sheds. The main shed is, roughly, 3m high x 3m deep and 5m wide at the bottom of the garden and has a clear facing south. It has a flat roof with a 100mm drop to the west for water run off.

Although it has a clear facing to the south it is still quite close to the house, around 9m, and only ~13m from the house opposite to the west. At this location and height below the house roof lines it'll get shaded. At this time of year from 1700 GMT with a first light, direct sunlight, from around 0500 GMT (very approximate times).

What I'd like to do, given the mains has been removed, is install an off grid solar PV (with a view to being an on/off grid system in the future) to run 12v lights, 240a/c for hand tools, chop saws, bench saws, etc and a radio (having entertainment in the shed is a good thing  ).

Given the position of the shed is it worth the effort to install a solar PV system?

TIA
del

[SeanB]

Solar for lighting and light loads will be a doable thing, but you will have to install a lot of panel to support power ttols, and the battery bank will be quite big as well, to handle the switch on loads of power tools. You might want to look at a small system to do lighting, light loads like your radio and have an outdoor extension lead that you unwind and plug into a socket for power tools. With 15m2 of roof you will be able to have around a 2kW panel array, and probably at that size you might look at having a grid tie inverter and run mains out to the shed again.

[del]

Thanks for the reply SeanB.
I figured that there was enough for lights and the only tools in the shed are quite a light load and they don't run for long periods. I'll have to read the bumf that is on the sides of the machines to make further decisions.

At this time of writing,1745ish, the chimney pots have just now hit the shed roof on the northern end of the shed about a third of the way down the width. Can't put too much on the roof as it's strength is in question. I think a max of six panels, evenly spread, would be about the limit (depending on mounting used).
 
Before I posted I only had the vaguest idea of one or two PV panels, an inverter, an MPPT charge controller and a couple of 12v 125ah batteries. I think I'll have a further read and have a more serious planning session.

Cheers,
del

[SeanB]

Most power tools draw over 1000VA, and often 3-4 times that during start up which means any inverter and battery bank you have will have to be sized to accommodate that. As well you will have to insulate the battery banks or the whole shed so that it does not get below freezing in winter, as the cells can freeze if it is cold enough. In most cases you have a wooden base and sides for the cells and some top planking to keep them warm enough, keeping it ventilated enough to not build up gas but not exposing them to cold draughts, as they will warm up during the day from charging and stay warm during discharge.

[kibi]

I have just set up my solar powered shed. I have a 1KW array on my flat roof shed. I have a 12V 750Ah battery bank. i also have a bigger shading problem than you do, I currently lose the sun after 2:00pm. However, I do generate enough energy to run a lathe, milling machine, reflow oven and electronics desk without too many issues. I did have a problem the other week when the skies were very dark, but I got a full charge again after three days.
My 2KVA inverter is quite happy with the angle grinder or circular saw. Although these machines use a lot of power, they don't consume a great deal of energy due to the short ammount of time that you actually run them.
My batteries are sealed AGM types which can be kept inside the shed to keep them warm.

Check my thread in this forum for details of how I put it all together. I think what you are planning is perfectly achieveable. With a 1.5KW array and better insolation at your site, you should have plenty of energy.

[del]

Thanks for the replies. kibi, nice work space you've made and I think, because of your situation, my solar shed is a go project! 
Got to make a list, read lots, watch youtube vids, ask questions, see what's about, find out who's done what that might work, weigh things up and spend money and time on this.

Thanks all,
del

[kibi]

No problem.
I run a 12V system so that my homebrew lights will work. However a 12V system is deemed a bit if a "toy" system, but I run 12V because it is easier for my 12V loads. My PC is 12V and lights are 12V. The inverter that I found out of an ambulance is 12V, so it all marries up.
It would seem that you are a bit serious about getting a good system in place? May I tout the benefits of a good charge controller? In my opinion, Midnite offer the best available these days. On a 12V system, it would handle a 1.5KW array without many issues in our climate. On a perfectly sunny day it may max. out, but how often does that happen in England? My 1KW array has maxed out at 806W so far, which is about the maximum NCT I should expect from new panels.
The Classic 150 is a fantastic controller, if you are up for it, I'd suggest that one. Sure enough, do some research, but I don't think you'll find a better controller for your application.
Batteries are a bit of a minefield. I rang up a UK supplier with my mind set on a certain brand and they honestly told me that they were shit. Their best option was my second choice, and I am happy days.
Next thing, do not buy a crap inverter. I like my Victron inverter. I've stated the loads that it supports earlier on, but I neglected to state that I made a mistake one day. I assembled some PCB's and put them in the reflow oven. Everything was good until I decided to apply some paste to the next set of PCB's without checking the pressure of the compressor tank. The 1KW oven was on, and now the 400W (nominal) compressor want's to start. The startup current of a compressor is not to be underestimated, but the inverter was OK with it, the lights flickered, but everyone was happy. The charge controller protested a bit because of it's arc fault protection, but that was easily cancelled out.
I have a Victron inverter, but here are many other off grid inverter options out there. The Germans do some good ones, Studer, SMA are some German brands. Victron are from the Netherlands. I used to work on Victron stuff when I was little. The English don't seem to produce any good inverters I'm afraid.
So, in short, it is a go. I only do evenings in my shed. Full time may be a problem especially in winter time, I don't know, I haven't done an English winter with my setup yet.