BUG: Cleaning Solar Panels

[nelsonic]

Today after finishing the stairs #136 I went upstairs to the roof to do a quick inspection.
I noted that all our solar panels are covered in dust:

Dust/dirt and pollution on the solar cells can cause a 25% decrease in solar panel efficiency.
https://www.popularmechanics.com/science/energy/news/a27112/pollution-can-block-25-percent-of-solar-power
Some articles I read say the drop in output can be as high as 60%, but let's keep this conservative for now.

We have 10kW of panels and let's go with 4 hours of sunshine per day.
If we are losing 25% per day it's 10kWh which at our current cost of €0.1544/kWh is €1.54/day.
Multiplied by 30 days it's €46.20.

Note: we are not really "losing" this much money each day, and our recent electricity bill #70 (comment) is not this much. But if we are going to be using our Air Conditioning or Heating, we need to ensure that we are getting the most out of our considerable investment into solar.

Proposed Solution

I propose that as part of the garden water points (water well installation) we install a water pipe up to the roof
Then we can either have a timed irrigation system that sprays water on each panel once per day
or invest in a Pressure Washer that can be used once a month to deep-clean all the panels.

e.g: https://www.leroymerlin.pt/Produtos/Jardim/Maquinas-de-jardim/Lavadoras-de-alta-pressao/WPR_REF_19299700

Water Source

When the Water Well people add the pipes and taps to the garden, we need them to add one to the roof.

The water line only needs to be a basic hose pipe, it doesn't need to be anything fancy.

Priority?

The reason I've applied the bug and priority-2 labels to this issue is because the inefficiency of the panels is costing us money each day. So the sooner we resolve it the sooner we stop wasting money.
On an annualised basis the lost power due to dust is considerably more than installing a pipe and either of the proposed solutions.

Dependencies?

Given that we have blocked the finishing of the water well until the green room is done #14,
we should prioritise that ASAP and get Carlos/Pedro to come and at least build the foundation.
Once the foundation for the green room is done, we can finish the water well and the garden.

Todo

• Contact the Solar Panel Suppliers to ask what they recommend for keeping the panels clean.
• Speak to Carlos about the Green Room
• Speak to Water Well people about installing a pipe to the roof as part of the garden water points.
• Decide which method of cleaning we are going to adopt

[nelsonic]

Last night it rained lightly here so I just went up to the roof to check what effect a bit of rain has on the panels. 🔍

The cells are less dusty as the rain has cleaned them off a bit:

But they aren't what anyone would describe as "clean" so we are still losing power.

@iteles given that you want to turn on the heat pump today to start using hot water, 🥶
do you think it could be worth trying to see if the hose pipe can reach the roof from the kitchen? 💭

[iteles]

We can try!

I'm not convinced that just a hose pipe without the pressure washer will make much difference but I don't want to buy the pressure washer until DAPE have confirmed care instructions.

I have emailed them to confirm.