I see countless posts about what do you need for a solar installation in your shed and the answers from people can range widely, so here is the ultimate guide for solar sheds.
Firstly I will starts with the sheds ability’s to hold the weight. Many sheds can just about hold themselves up, therefore you may want to consider framing the shed first to make sure it can hold the panels. some 4×2 will do the job and put these down the corners, and around and across the roof space.
Solar:
Installing solar panels can be simple but how many solar panels do I need for my shed? you ask…
Solar panels provide power from sun light, the dimmer the sun, the less power they make, but what we need to do here is work out how much power they make, how much power you need, and how much power you can store.
For example, if you do not use the shed often, say only on the weekend; then you can charge the storage all week.
The load, which is what you will use, will drain from the battery, so therefore you can have smaller solar panels, as long as they are keeping that battery charged ready for the weekend.
Solar sun hours:
Sun hours are a bit different to daylight hours and im sure you have seen a solar curve but we would be looking at around 4 hours of sun in a day, this varies from summer to winter, so the charge time will vary over the year and the battery and solar can buffer each other, this is a must for loads when a cloud passes. you can read more on sun hours here
How much of a battery?
it is a bit of give and take, if you have 400w of solar and its making 400w and the load is 400w then the system is neutral and you are not taking power from the battery. If on the other hand you use 6kwh of power over the weekend, then you will need to have made 6kw of solar power over the week. Taking into account those sun hours
So the math here is 6/7 which is only 0.85kwh per day from the solar to charge that battery.
Solar power can run inverters to provide power, but you do not need to match the solar to the power required in the loads when you have a battery. It is possibly better to look at this in amps rather than kW.
If you have 76v of solar with a peak current (amps) of 12a and a 12v 1000w inverter, the inverter will draw 1000/12 = 83 amps for peak continuous power.
When you power factor the solar array you would get a factor of 6.3 and this then would result in a output current of 76 amps, this would cause a draw on the battery of just 7 amps.
As you would note that using 1000w over the day, will draw down the battery by 7 amps per hour, provided that you have no clouds and that the array is running at peak power. which will not happen. But then will you use 1000W continually for the day? probably not.
Its a good idea to over size the battery so that you have reserve, and it is a good idea to over size the solar.
Kit list.
Solar panels.
DC isolation (PV)
Charge controller.
Breaker
Battery
Breaker
Inverter
MC4 connectors. PV cable, Cable clips.
Solar panel mount system.
How to mount the solar panels on a shed?
Hangers, mini rails and framed are popular as well as Z brackets and A Frames.
Hangers bolt to the roof joists and are a set of nuts bolts and washers, you then attach rails to these and the washers with sealant will work to keep things dry.
Mini Rails for metal, corrugates and felt roofs, These are flat rails with a base that has a rubber seal, these at the most easy installers as it allows for mistakes and inaccurate placement. you do not need rails here as they are the rails and you would need the solar panel clamps to fit them.
Framed, this can be variously applied to a timber exo frame around the roof to support the panels above the roof, to a mounted frame that is connected on the sides and floats over the roof.
You could have a ground frame too. The frame is can be extrusion Alloy or Unistrut if you wanted something a bit more engineered.
Z brackets attach to the pre drilled holes under the panels frame, they then bolt/screw to the surface, these can work in various mounting positions, but can be a little fiddly.
A frames are the adjustable mount system where you would bolt these to the pre drilled holes in the panels frame, they have a flat bottom which can be used to bolt them down two a surface. The good thing here is the adjustment for summer and winter, but you will need to manually adjust them.
Hooks are great for tiled shed roofs, there are a number of different types to suit the tiles, and you would lift the tiles to fit these to the joists, you then fix a rail and then clamp the panels to the rails.
You may also want a solar pergola or to wall mount your solar array
Measure and monitoring
This really is a form of solar stalking and can be an obsession for many. The basics that you need to monitor is the battery state of charge. The current in and out of the battery will give you the available power and the rate of charge (solar) and discharge (inverter load).
You can go OTT with solar voltage and current monitoring, as well as power shunt to the battery output if you really need to know how effective you charge controller is. and the same can be said for the battery to inverter and of course not forgetting the inverters output. Maybe even the AC loads, voltage and current?
most MPPT charge controllers will give you information, but for sheds i would suggest that a AIO (all in one) takes up less space and costs less as it contains all the parts that you need, so you are just connecting solar and the battery (4 cables) and your pretty much done, this should show how things are working together for the average power stalker.
If you can questions, then ask in the comments below.
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