Cutting trees for marginal solar improvement

[NoGoodAtScreenNames]

I’ve been trying to read up a little more on the impact of shading. When we made the decision to go solar it was based on the trees being there. I found a white paper for my panels Solaria Power XT that analyzes the impact of different types of shading. Granted, these are lab tests but it is interesting to see it cover some of the prior comments about not just the percentage of shade but it’s direction too being important.

The multi path flow in the panels deals with shading better that a snake an up down and over pattern.The exception would be the straight vertical where the panels under perform vs. the more traditional orientation.

(broken link removed to https://static1.squarespace.com/static/568f7df70e4c112f75e6c82b/t/5ebad31ca375f52b5424f27d/1589302053132/shading-whitepaper_Rev-02.pdf)

So those vertical trunk shades will be problematic. My arrays are oriented left half / right half. One goes through each of the arrays, so I’m back on the fence and may take down after all...

Oh and here’s how the panels look on the roof. The shading is from early morning when the sun is just getting over the trees.

 

[semipro]

It seems to me that the real question is whether your annual production and net metering will cover your annual usage. If it does, don't sweat the shading.
Net metering in Virginia is rolled over annually so we're hoping to build up enough banked kwh in the summer to carry us through the winter.
I realize your net metering may be different.
PS- I appreciate the geekiness of looking at how solar panels are constructed to better understand the effects of shading.

 

[NoGoodAtScreenNames]

On a kwh basis this will nearly cover my yearly use. However, my net metering kind of sucks. It encourages load shifting our use to the daytime when the panels are running.

I pay $0.16 per kWh for anything I pull from the grid and get paid back the wholesale rate of $0.04 for anything I send back to the grid. It’s not rolled at all. Basically excess daytime production reduces my nighttime rate by 25%. There is talk of updating the metering rules to have some rolling period - even day to day would be good. But I’m not banking on it.

 

[semipro]

On a kwh basis this will nearly cover my yearly use. However, my net metering kind of sucks. It encourages load shifting our use to the daytime when the panels are running.

I pay $0.16 per kWh for anything I pull from the grid and get paid back the wholesale rate of $0.04 for anything I send back to the grid. It’s not rolled at all. Basically excess daytime production reduces my nighttime rate by 25%. There is talk of updating the metering rules to have some rolling period - even day to day would be good. But I’m not banking on it.

Something like this was an option for us in Virginia too - buy at the retail rate and sell at the wholesale rate.
It was either this or reconcile yearly. We'll see how it all works out after a few years.

 

[semipro]

I pay $0.16 per kWh for anything I pull from the grid and get paid back the wholesale rate of $0.04 for anything I send back to the grid. It’s not rolled at all. Basically excess daytime production reduces my nighttime rate by 25%. There is talk of updating the metering rules to have some rolling period - even day to day would be good. But I’m not banking on it.

That stinks. I read through Mass. net metering and it looks like you reconcile monthly - not very helpful.

 

[NoGoodAtScreenNames]

That stinks. I read through Mass. net metering and it looks like you reconcile monthly - not very helpful.

I’m in a municipal department. I hear we are cheaper than for profit companies but they are exempt from a lot of regulations around solar.

 

[begreen]

We're coming to the end of our first contract with PSE. It paid the going rate for net metering and $0.54/kW annual credit at first. The credit dropped to about $0.48/kW, but still is ok. It was a sweet deal if you got in early. The caveat though was that the system and panels had to be WA state made. Our second array is under a fairly decent contract, but not as good. But the panels cost less by then and we already had the inverter to tie in to.

 

[John Ackerly]

I may have missed this, but if you use much A/C in the summer, those trees can really help. We are letting the trees grow tall on the north side of the house and on the south side, I climb up and trim them every year so they provide some shade but not on the panels.

 

[stoveliker]

I have some oaks in the West (ridgeline being North-South, equal # of panels on both sides) that shade late sun in Summer, and less late sun in Winter.
However, our system was designed to cover my yearly needs with the trees there - being lucky to have a meter that runs backwards in Summer (rather than getting paid pennies per kWh).

Given your metering, the question is whether your system was designed to have you financially break even, OR to produce as much as you use, with the latter still not being break even in your metering.

The former situation means nothing needs to be done. In case of the latter, cutting trees will help, but not much given the metering. Instead, it might be worth looking into a battery system, to avoid having to pay for power used at night. Winter will still suck, but it's tough to change the rotation axis of our planet...

The bottom line is that cutting trees has much less effect than the financial situation of the metering. I'd leave them standing, unless you have other reasons than solar to cut them down.

That's just an opinion, and as we see above, you can find those all over the place...

Good luck deciding!

 

[NoGoodAtScreenNames]

We ended up taking them down after all. In the end it was a combination of solar, tree safety and letting more light into the yard and house. The trees don’t do much to help with the AC demand in the summer. Their shadow was gone from the house by mid morning.

In my original post I was worried about winter but not thinking as much about fall. The sun sinking lower with the leaves still on the trees was really delaying the upward trend towards my peak. I face SE so the morning to midday is most important to me. I took a look at the last perfectly clear days before and after the removal. You can see a more gradual uptick as the sun rises instead of the steep climb as the shadows cleared. So it definitely will be increasing my solar access for at least 6 months of the year. Whether that works to pay off the tree work, I’m doubtful. Whenever I have tree work done I always feel a little guilty before doing it and then being very happy after they are gone. That was the case here.

Got a good amount of wood out of. 5 large oaks in all, 3 of which helped with the solar. Looks like I’ll get about 4 or 5 cords out of it that I won’t be buying, so that helps too.