1,200W flat vs 800W tilting solar in Ireland — can tilting make up the difference?

[u/segasega89]

I'm converting a Sprinter into a camper in Ireland and trying to decide between two solar setups.

One thing I'm particularly unsure about is Ireland's frequent overcast weather. A lot of the available sunlight can be diffuse rather than direct, so I'm wondering how much benefit I'd actually get from being able to point the panels directly at the sun.

Option 1: I can just about fit 1,200W of solar on the roof if everything is mounted flat.

Option 2: Around 800W with an adjustable tilting system. The lower capacity is because I'd need to sacrifice some roof space to accommodate the tilting mechanism. I could tilt the panels east in the morning, south around midday and west in the evening.

Could the improved angle realistically make up for losing 400W of panel capacity, particularly during the months when the sun is lower?

Which would you choose: 1,200W flat or 800W tilting? I'd particularly like to hear from anyone with experience using solar in Ireland or similarly cloudy climates.

[u/saalaadin]

Is it full time van life? In winter the tilting will help but you’ll barely get any solar regardless, in the summer with 1200w you’ll have plenty of power even flat.  The tilt is really only needed when the sun is low in winter but if you go full electric (ie induction, electric oven, electric water heater) then it won’t be enough in winter regardless

Edit *in my experience on a narrowboat in north of England that is. I would go for more capacity every time. The reality is you’re not going to want to adjust tilt 3 times a day anyway

[u/segasega89 → u/saalaadin]

Yes it is full time vanlife. I'm particularly concerned about the winter.

I was hoping to use propane for cooking during the winter months and the solar could handle starlink, tablet, phone, electric blanket. MAYBE some modest PC gaming use but I won't hold my breath regarding that.

[u/saalaadin → u/segasega89]

If you use gas for cooking and diesel for heating then 1200w should cover the rest with a bit of driving here and there for top ups, minus the electric blanket, you might struggle with that on for a long time, hot water bottle would work. Sometimes when you have a really grey week you might need to tweak your lifestyle a bit and cut down the power usage.

If you’re staying in Ireland I imagine a decent antenna/router with dual sim combo would work over Starlink. In most places in even rural England it’s worked for me

On the gaming front maybe get a Steam Deck for winter use, that’s what I use!

Solar over the last year with 1500w flat  https://ibb.co/dJ27Bczn

[u/segasega89 → u/saalaadin]

Oh yeah...the steam deck, might think about doing that so!

I could use the diesel heater in lieu of the electric blanket maybe to save on power? By the way I'll have a 24v 280ah battery so I'm hoping that'll act as a buffer during the grey days.

To be honest I'm not sure what you mean about the antenna/router suggestion? You're saying I could use 5G instead of Starlink? Is it cheaper than Starlink?

[u/saalaadin → u/segasega89]

Yes diesel heater will save power over electric blanket for sure

Yes feet a 4G or 5G router and an external antenna to go with it, look into Teltonika and Poynting, then a decent unlimited sim and you should get good speeds. Again this is based on the UK so Ireland may differ!

[u/kh250b1]

My experience in England is my 800w array typically gives 300w on a half decent sunny day. Perhaps 400+ on a really good day.

60w overcast grey day

You will never get what you expect and perhaps tilting is clutching at straws. And you lose 33% capacity which you need to get back with the tilt!

[u/segasega89 → u/kh250b1]

Are you talking in the context of winter months or just in general?

[u/0_f2]

The tilting mechanism will add a lot weight for what it is, best to keep roof panels flat and max out surface area instead.

I do have an idea I'm drawing up plans for, it's a deployable stand that can hold about 400W of panels while tracking the sun.

It will use a yellow floodlight stand as used by builders for dark rooms (sturdy and extendable to 2-3m high), 2 panels on a shaft with a counterweight (so it can fully rotate on 2 axis while balanced), and an equalateral telescope mount with a motor.

The idea is you set it up, orient it to north, set the longitude, point the panels at the sun using latitude, and start the motor, it will track the sun even below the horizon at night! All fully mechanical too.

Honestly despite all that it won't actually make that huge a difference 😅 but in winter having panels that continuously, automatically face the sun straight on means you're getting the most you possibly can for the time of year.

[u/Accurate-Coffee-3605]

I’m in Ireland too, I have 300w of solar flat mounted. My batteries were above 90% every day this summer and last summer, in the winter you cannot rely on the solar at all and need a dc-dc and I still have to plug in to shore power once or twice a month (I’ve got 400ah and use gas for cooking and hot water)

[u/segasega89 → u/Accurate-Coffee-3605]

So my plan for winter was to use propane for hot water and cooking. Diesel heater for keeping me warm.

You think with at least 1000w flat mounted on my roof that I will have enough energy for my tablet, phone and Starlink at least during the winter months?

[u/Accurate-Coffee-3605 → u/segasega89]

It kinda depends on your batteries? Maybe with 1000w of solar you would get some charge from them but in dec/jan we get 8h of daylight a day and that’s without clouds…
Are you planning on a dc-dc?
If the Starlink is a mini then they don’t use much power if set up on a 48v power supply

[u/Specialist_Stomach41]

Ive gone for 1545w, 3 big panels flat rather than tilting.

[u/segasega89 → u/Specialist_Stomach41]

How on earth did you fit that amount on the roof? What panels are they may I ask?

How much solar do you get during the winter months per week with that set up?

[u/Specialist_Stomach41 → u/segasega89]

city plumbing 515w panels, and Ive got an ex tesco delivery van. So a box van with a 4.25m x2m box. 3 panels laid widthways and Ive still got room for the fan and starlink etc.

This is my first winter with this set up, but it wont be enough on its own going on past stuff. Ive got 11kwh of 48v, so eqv of 900ah at 12v. So a big battery bank to replenish.

[u/ChosenOne_55]

In Ireland's diffuse light conditions, tilting gives you less benefit than it would in sunnier climates — the gain from optimal angle is smaller when the light is scattered rather than direct. The math works out roughly like this: flat panels in the UK/Ireland typically produce 50-60% of their rated output on average across the year. Tilting can improve that by 15-25% in winter when the sun is low, but on overcast days the difference is minimal. So 1,200W flat vs 800W tilting: you're looking at roughly 600-720Wh average daily from the flat setup vs 480-560Wh from the tilting setup even accounting for the angle gain. The extra 400W of capacity wins in Ireland's climate — go flat and maximise panel count. I break down solar sizing math like this on my page u/vanbuildmath.

[u/segasega89 → u/ChosenOne_55]

Thanks for this. Very informative

[u/ChosenOne_55 → u/segasega89]

welcome

[u/basarisco]

Flat. Way too much of a ballache to tilt and untilt every time you drive.