The Greg's Grid Tie Solar Project

[Gregski]

To go from a 12 volt system I had to upgrade to a new 24 volt inverter, this 1300 watt one can be had for $90 bones on eBay, this is already factored in the total cost of $1,200 the last $100 bucks of that budget went to cables and beer

so theoretically this metal can can handle 300 watts more than the five 200 watt panels can shove into it, but these panels probably will run at 75% efficiency so I could even throw a sixth one up there on the roof if I'm feeling cute one day

[Gregski]

this does not bother me at all

[Gregski]

short story, longer

I had to take down my free floating solar panels this winter cause we had the worst winds I have seen in the last 100 years and I was afraid these may fly off and decapitate someone, well when I decided to load them back up on the patio, one custom milk crate riser went missing, so one solar panel is flat out like a lizard drinkin' and we leave on a three week holiday to Australia tomorrow so I will not obsess over this at all while relaxing Koala style

by the way this is my Solar System South currently featuring 800 watts worth of panels, well maybe 700 1/4 lol

[Gregski]

and there she was, sitting there all alone, just begging to be adopted

[johu]

Is there no wind in summer?

[Gregski]

Is there no wind in summer?

not the blow the roof off a house, knock over fences, and uproot trees kind

we only build fences for 15 years and in California we love fences so everybody's got one, on the East coast only if you have a pool

Gusts top out at nearly 70 mph in Sacramento as wind storm batters Northern California (I was trying to find some pics of smashed BMWs lol)

More than 300,000 customers had their electricity knocked out in and around the state's capital, according to a Sacramento Municipal Utility District online map of outages overnight.

[alexbeatle]

Thank you for your awesome project!
I live in the NorCal too and my house HOA doesn't allow DIY solar on the roof.
Your project just shined some light on my vision to have simple, portable and expandable solar.

For energy monitoring (and overall home automation) have you looked at Home Assistant? Been using it for a year or so and love it. You can build beautiful dashboards and home automation with everything running off Raspberry Pi.

[Gregski]

Thank you for your awesome project!

thanks

I live in the NorCal too and my house HOA doesn't allow DIY solar on the roof.

I looked into this a while ago and I am not sure if this is the same article but it turns out that actually in California the HOA can not deny you installing solar, they will make you jump through a bazillion ridiculous hoops but they can not deny it, and I think that goes for putting it on the house ie roof

Can an HOA deny solar panels in California?

"Fortunately, an HOA cannot deny solar panels in California. If your homeowner’s association (HOA) is giving you a hard time, look into the California Solar Rights Act. This legislation protects your right to install a solar energy system and outlines the guidelines an HOA has to follow if they want to place reasonable restrictions on your solar installation."

[Gregski]

LET'S TALK BOTTLENECKS

I know that when I built this system I just bought components that had human readable round numbers, like 100 watt solar panels instead of 80 watts and I bought a 1000 watt inverter instead of a 1300 watt one, but if we were to scope out one of these systems for maximum performance what would our limits be specifically for a Grid Tie System? In other words if we revisit the diagram below, where is our bottleneck? what is the limiting factor? or is there one? or is sky literally the limit?

So looking at the Grid Tie System diagram above which one of these would you say is the bottleneck? What limits a Grid Tie System?

• A. Solar Panels

• B. Grid Tie Inverter

• C. The house circuit aka Power Unit

• D. Utility Grid

• E. Your Wallet

we can ignore the System Switch which I have no idea what they mean by that showing a power chord, lol same goes for the Utility power switch

[Gregski]

so the correct answer is:

• C. The house circuit aka Power Unit

[Gregski]

[Gregski]

well let's use a US house as an example, depending on who you ask (and wars have been fought over this) we have either 110 volt circuits or 120

most of us here in the States use this interchangeably and call our outlets 100 or 120 or 110/120 or sometimes even 115 (don't get me started on that)

I don't care what you call it but the best way that I can explain it is what a professional electrician once told me, back in the day (oh boy here we go...) back in the day the circuits in the houses in the States were 110 volts, period end of discussion. that's why if you talk to an old timer electrician she knows 110 and 220 volts and it's her way or the highway

now over time the electrical power grid got bigger and more better and newer homes (those not built in the 1950s, lol) started seeing 120 volts in their wall sockets, so that's what the new Young Padawans aka electricians know and in their world it's 120 or 240 volts

I have tested this theory and the house I grew up in aka my mamas house built in 1958 shows 110 volts on the Killer Watt meter plugged in to her wall socket, and my house built in 2002 reads 120 volts

alright, alright already, Land The Plane !!!

[Gregski]

so we start with a house with 110 volts in the wall socket and to calculate max power on that circuit we multiply 110 volts times 15 amps since we know most houses in Amerika run 15 amps and we get 1,650 watts

110v x 15a = 1,650 watts

but we are not done yet, cause supposedly 15 amp breakers don't break at 15 amps, Say what? there's a safety feature that makes them flip at 80% so 15 amps time 80% is 12 amps, wait that sucks !!! yes it do, but so be it... so back to the drawing board

so we start over 110 volts this time, multiplied by only 12 amps gives us 1,320 watts

110v x 12a = 1,320 watts

ok, great so what? well this is the max amount of traffic that can run on this circuit regardless of the direction it is going, so it's not like if there is a device on there using 300 watts and we are pushing 1,000 watts of solar back in, then the net is only 700 watts, that's not how it works !!! we are actually running a net of 1,300 watts on that circuit and it's close to flipping the breaker at 1,320

so since our Grid Tie Inverter is nothing more than yet another device plugged into the wall our house don't know or care if its using electricity or for a lack of a better term creating it, so 1,320 is the max on a house with 110 volt 15 amp circuit

so that's why these guys make a 1300 watt Inverter

[Gregski]

OK, now you see why we got that history lesson, cause now we do the same for a newer house running 120 volts to see if it makes a difference, so since we learned it also can only go up to 12 amps (15 amp breaker trips at 80%) we now do the math

120v x 12a = 1,440 watts

let me guess they make a 1,400 watt grid tie inverter?

ah, yup!

[Gregski]

Now if you recall I went with a 1000 watt inverter, I did it cause I like round numbers but it inadvertently put me in a safe zone where my inverter won't exceed the capacity of the circuit in my house whether it is 110 volts or 120 or even if something dinky is still plugged in on that circuit which I deliberately try and avoid and suggest you do the same

[Gregski]

Great, so now what, what if I want a 2,000 watt system, what if I want at 2,800 watt system or a 5,000 watt system?

[johu]

Are you seriously saying a house in 'merica can't pull more than 1.4ish kW? That wouldn't even run the heatup phase of your washing machine, let alone running the dryer at the same time.

Also the inverter is an actual source of power. So when it does 1000W and your device needs 2000W then you'd only be drawing 1000W from the grid.

[Gregski]

Are you seriously saying a house in 'merica can't pull more than 1.4ish kW? That wouldn't even run the heatup phase of your washing machine, let alone running the dryer at the same time.

Also the inverter is an actual source of power. So when it does 1000W and your device needs 2000W then you'd only be drawing 1000W from the grid.

No, I am saying houses in the US have many 120 volt 15 amp circuits, and you should only plug one Grid Tie inverter per circuit, so if you want to have two 1400 watt grid tie inverters make sure you put them on two separate circuits, that's all I was going to say, like I have done, I have one grid tie inverter plugged in to the outlet on the circuit for my back patio and another grid tie inverter plugged in to a different outlet on the circuit for my garage, of course both of those circuits run to the same electrical panel which in addition has the 240 volt circuits for the heating oven, and Air Conditioning etc.

[johu]

Oh, now I get it. Thanks

[MattsAwesomeStuff]

cause supposedly 15 amp breakers don't break at 15 amps, Say what? there's a safety feature that makes them flip at 80% so 15 amps time 80% is 12 amps

Mmm... you sure about that?

I thought it was that the breakers trip at 15A, but you're not allowed to spec more than 12A of stuff wiring into that circuit. So a spaceheater is 1200-1400w for example. Or for lighting circuits you max out at 1440w, even though the breaker can handle more.

Maybe I have it wrong.

[Gregski]

Mmm... you sure about that?

I thought it was that the breakers trip at 15A, but you're not allowed to spec more than 12A of stuff wiring into that circuit. So a spaceheater is 1200-1400w for example. Or for lighting circuits you max out at 1440w, even though the breaker can handle more.

Maybe I have it wrong.

I'm no expert, so please take a look How Circuit Breakers Work

"As you add up the electrical loads, keep in mind that a wire rated at 15 amps can carry 15 amps all day long. However, 15-amp breakers and fuses can only carry 12 amps—80 percent of their rating—on a continuous basis. Continuous basis is considered to be a circuit loaded to capacity for three hours or more. This 80 percent rule applies to all breakers and fuses."

[MattsAwesomeStuff]

"As you add up the electrical loads, keep in mind that a wire rated at 15 amps can carry 15 amps all day long. However, 15-amp breakers and fuses can only carry 12 amps—80 percent of their rating—on a continuous basis. Continuous basis is considered to be a circuit loaded to capacity for three hours or more. This 80 percent rule applies to all breakers and fuses."

I'm interpreting "can only" to mean "should not have more things plugged into them, per our rules, than could".

Also, if you think about what it says next, continuous basis is 3+ hours. So do you think that a 15A breaker is not going to trip if you load it more than 12A for less than 3 hours, but somehow will after 3 hours? What's happening at hour #3 that wasn't happening at 30 minutes? The thin bimetallic strip has certainly reached thermal equilibrium within a matter of a few seconds.

Also, here's a "trip chart". Careful, they sometimes flip the X an Y axis. But in short, look where they bottom out. It's greater than the trip capacity. I.E. 15A might actually blow eventually, north of 16 or 17A most likely. Though in the very short term, it can survive several multiples of that. There's even different design curves based on whether you have a resistive/inductive/whatever load.

https://i.stack.imgur.com/CwAqH.png



None of them that I've seen (in 3 minutes googling) went below a multiple of 1 (i.e. no 15A breakers trip below 15A).

[Gregski]

so since it has been a month since I threw the new larger 200 watt solar panels on the roof facing West I figure I'll provide you all with a little update on how this system is doing, I am quite happy with it, but I know unobstructed by shade (from my own house) it could do more better

currently on my best days I capture just above 5 kWh of sunage per day with a max of just over 600 watts per hour which means these panels are working at what I would call 60% net efficiency (net meaning I am looking at the data after it funnels through the inverter and not before so there is some loss there)

but as you can see from the Bell Curve we are capturing something from 7 am until 7 pm so that's goodness

Future plans including adding another 200 watt panel for a 1,200 watt total since at 60% (that's only 720 watts net) so still acceptable for this 1,000 inverter to swallow

[Gregski]

I was just fartin' around AMAZON when I saw these 100 watt solar panels for only $69 bucks and I thought I would share, I don't like posting links cause they will expire, but here's enough info on them to find them by searching AMAZON

What an inexpensive way to get your feet wet, this plus a 1300 watt grid tie inverter off eBay for $89 bucks [see a few posts above for details] and you're on your way, and remember if you don't want a 12 volt system, just get two of these and connect them together in series (positive lead from one panel plugs right in to the negative lead of another, it doesn't matter which lead is which) this adds up the voltage and now you have a 24 volt system, then add more panels in pairs like that


JJN 9BB Solar Panels 12V 100 Watt Monocrystalline Solar Panel High Efficiency Solar Module PV Charge for RV Battery Boat Caravan and Other Off Grid System(Random Color)

OR


WERCHTAY 100 Watt Solar Panel 12V/24V Monocrystalline, High-Efficiency Module PV Power Charger Solar Panels for Homes Camping RV Battery Boat Caravan and Other Off-Grid Applications

[johu]

currently on my best days I capture just above 5 kWh of sunage per day with a max of just over 600 watts per hour which means these panels are working at what I would call 60% net efficiency (net meaning I am looking at the data after it funnels through the inverter and not before so there is some loss there)

My 8.9 kW of panels do max out my inverter at 7.8 kW for a few hours over noon:

So it should be possible to get near 1000W from your. The angle seems pretty much perfect. I found that the "Grid Tie Inverters" don't do a good job at MPP tracking and also have poor efficiency. MPP of my one panel system here is 30V but the inverter runs it at 26V. That's 13% loss right there. Efficiency is about 85% for my 500W model, another 15% gone. So 28% losses in total almost line up with the 60% you calculated.