Number crunching

Do the panels have any additional protection?

 

Not that I know of. What kind of protections can you install on the rooftop panels?

 

Sandwich panel

https://www.researchgate.net/figure/Sandwich-panel-structure-of-a-crystalline-photovoltaic-module-A-Single-glass_fig1_353521384

 

Thanks but it does not look like anything commercially available being on Research Gate. Even if it exists as commercial product, I imagine that would increase the cost of the panel to the point no one can afford it. Besides, the problem we just had would not be prevented by the impact resistant glass. We did not have hail, we just had freezing rain.

 

Regular ice build up might make a defrosting system worth while. Even thin, the wires will cast a shadow on the cells. Vertically mounted, bilateral panels might be a better option with such concerns. Otherwise, a deicing solution for sometimes events, as long as the chemicals won't damage to panels.

 

I dealt with snow by raking snow off the the panel with a long snow rake and wide rubber squeeze so far. But there is nothing I can do about freezing rain, especially when snow followed by freezing rain like last night event. I am not familiar with solar panel defrosting system. No option like that was ever suggested by the installer. And now, all the panels are installed on the rooftop, I don't see there is any easy and cost effective way to retrofit such system. I will just have to wait for natural warm-up. Once the day time temp hit above freezing, it should not take long for the layer of frozen ice/snow to slide off.

EDIT TO ADD: I found this site Snow melting system for solar panels | Thermaltt
Looks like this type of heating film is installed on the back of individual PV panel. I have no idea what the cost of material and installation. Maybe DIY installable looking at the video. But only for uninstalled panels. Once they are up on the roof, you can't do anything unless uninstall all the panels and do it all over again which I am not going to do.

 

Daytime getting longer, every sunny day is the new record for the system. Today was 74.5kWh.
@Leadfoot J. McCoalroller, your system is similar size as mine. But our rooftop is not optimized for the south facing best azimuth as your system. Also I am in higher latitude than you. If 74.5kWh is the midpoint for me, then I think over 100kWh/day is coming soon.

 

Even though we have had plenty of April showers this month, daylight getting longer every day, sunny day is always a new record solar production for us. Yesterday was the new record with 90.7kWh/day. We had 1.2mWh production last billing period which exceeded our consumption, giving us surplus to bank for the winter. This was even though we switched our car from PHEV to a BEV. This billing period, we are on track to produce 1.5mWh.

BTW, we just finished installing 5 units of mini-split heat pumps to cover our entire home for heating and cooling. Unfortunately, we can't convert to electric heat pump water heater due to our home lacking suitable location to put it (i.e. no basement). So, we are keep using fossil fuel for hot water for time being. I have a plan to remodel our home to add a room to accommodate the hot water heater, but that is probably going to be next year's project. I will never recoup the cost of all addition and remodeling, but at least I will be enjoying the energy independence when that happens.

We are also at the 10 year cycle of major appliance replacement period. We started with replacing the electric oven/range to IH oven/range first. It is a finicky appliance to use. My wife is not so sure if she likes it yet. We will give a try at least a few more weeks to decide whither to keep it or return it. On another front, I am feeling very good about cashing out a big portion of the equity fund in my tax deferred retirement account last year at the record high level. Now stock market has tumbled down 15-20% since last year's high mark, while market keep losing money, the cash I took out and invested into solar system is earning money steadily, and I paid no tax on the money taken out because of the IRA tax credit. My rough calculation is that I am making (saving) annual ~4% ROI on solar investment, that's far better than what the stock market has done so far this year.

 

How many solar panels do you use? What is the total area of these solar panels?

 

35 panels on the size of our roof. Total area would be 67.8 in × 44.6 in x 35 panels.

 

So far for the first ~4 months of operation, the system has been performing flawlessly. The annual production estimate from the system by the company who installed it was 13,382kWh. This number if realized would offset 100% of our electricity use based on our historical consumption average of 12,732kWh/yr.

What I did not know was how the company came up with the production estimate of the system. Using public site like NREL PVWatts Calculator I get 17,400kWh annual production result shown below using default value for adjustments but using the exact spec value provided by the solar installer. The number is 137% of the solar company's estimate. I think it is under ideal condition and it is an overestimate. On the other hand, the solar company may have underestimated the annual production to up sell system larger than needed. But so far, in the first ~4 months, our system production is on per with the solar company's estimate or slightly more. With addition of a BEV and whole house heat pumps, our annual electricity consumption may go up in coming year, so with current system it may fall short of off setting 100% usage. But actually, rather than producing excess amount of electricity, (we don't get paid from the utility for the surplus of electricity generated), we would rather produce slightly less than net-zero to make it cost effective.