DIY solar/worth the cost?

[stevehull]

Here is another advantage of Enphase . . . .

A customer had an Enphase 6 kW system (I installed) where the Envoy (power and energy recording box) was acting abnormally. This box gets house wired digital signals from each roof mounted Enphase microinverter, converts them and sends info via Wifi or USB cable to the standard home internet router box. Then the Enphase Enlighten internet site allows you to see system total power, daily energy, each microinverter parameter (voltage, current, power, temperature, etc, etc). Very nice for geeky people like me.

Anyway, instead of the nice smooth parabolic power output that you should get over the day, there was nothing and then large square wave jumps in power output. Then all would be OK. The daily power output was appropriate, but the output curve was screwy.

I checked all my electrical connectors in roof junction boxes, at the circuit breaker and nothing was wrong. 120 V on L1, 120 V on L2, all OK. This is stuff I know - what was going on?

Called Enphase . . . They are able to look at FAR more data that I can see on their site. They have the means to see data, and where there is a fault, to capture all kinds of information (voltage, current, frequency, phase angle, etc) down to the msec on each microinverter. Turns out there was a transient L1 L2 imbalance. Normally L1 should be ~ 120 V and L2 ~120 V for a total for ~ 240 V across L1 and L2.

For a brief moment (a hundred msec, sometimes much longer, but always transient), these potentials became ~ 80V on L1 and 160 V on L2. The microinverters will accept some imbalance (5 V or so), but not this big. Note that the total potential is still 240 V - so the inverters are still sending out power. But the inverter was not sending it out to the internet in real time.

Both the Enphase tech and I immediately recognized this as a bad neutral. If the neutral is flaky or floating, then the ground is uncertain and you get odd split voltages on L1 and L2. The worst of this is that it was INTERMITTENT and incredibly short lived!

Enphase sent me the data by e-mail and I called the electrical utility company to come out and check the homeowners voltages - especially the neutral. They arrived and there was no imbalance at that moment.

The head lineman insisted that it was the customer's fault and a "capacitor was bad" on some 240 V appliance. He and a helper spent the afternoon looking and found nothing. Meanwhile I am looking at the electrical box behind their meter. This box has a wire "security" tag so that only utility people have access to that panel. This is a place that I cannot check.

Nothing in house - no issue with any 240 V appliance - and still no imbalance seen.

At this point, we are talking about having a voltage recorder put on the system and THAT is paid for by customer ($100 per day!!). The lineman also kept blaming the PV system and me (as I was installer) as the cause.

After they found nothing, and as a compromise, I suggested they look in "their" panel, the one the meter is mounted on to check those connections. "No, it can't be there" was the response. I persisted and said it would only take a couple more minutes.

Reluctantly, the panel was opened and each of the three lugs, L1, L2 and neutral were tightened (with insulated tools and rubber gloves on lineman). L1 was tight, L2 was a bit loose (took 1/2 turn to tighten), but the neutral was completely loose (3 full turns to tighten).

The utility repair person and helper were incredibly embarrassed, but I thanked them in front of customer and told them they did a GREAT job (never, ever piss off a utility person).

Now we had to wait to see if the problem came back. No it didn't and hasn't for months now. But here is the kicker . . . .

Turns out the customer had been having "odd problems" at times with appliances. Some lights would suddenly brighten, others would dim and some kitchen appliances would not work - then two minutes later they would work. Eeee gads! This had been going on for years (long before my PV install) and they just got "used to it" as it would go away. The imbalance was on a lot of the 120 V lines and it was lucky that nothing burned out.

Scary . . .

I called Enphase back and thanked them. They said they "see it all the time".

Bottom line - make sure your neutrals on your big junction boxes coming in from the utility are tight to the lug . . . .


Steve

[oil pan 4]

What do you know about electrical work.
Because going from not being able to add a circuit to your home or replacing a switch or receptacle to building a diy solar system sounds like a recipe for disaster.

[Roostre]

Originally Posted by oil pan 4

What do you know about electrical work.
Because going from not being able to add a circuit to your home or replacing a switch or receptacle to building a diy solar system sounds like a recipe for disaster.

I work in the power business. (Generation/transmission/distribution) 17 years mostly instrumentation and controls. Have friend that is a master electrician who is willing to help as I take good care of him when he does. I'm probably more comfortable with the project than most would be. It's actually the mechanical part (roof racking, shingle modification, snow load, wind load) stuff that I have blind spot in.

[stevehull]

Roostre,

I believe you need to have the system installed and OPERATING by Dec 31 of this year to get the 2016 tax credit.

There is always GTA (good until audited), but I like to get things done "cleanly" for the IRS. No sense waving any red flags in front of bulls . . . . .

You have a lot to do - but we can help you. First off, we need your month by month kWhr consumption for past year and the associated costs for kWhrs in the varying seasons and for differing consumption levels. This allows us to figure out how many kW system. Then we figure number of panels. Then we look at roof to see how panels can go up and where. That determines amount of racking and wiring.

Not trying to be scary, but old man winter is puffing up . . . . .


Steve

[Roostre]

Originally Posted by stevehull

Roostre,

I believe you need to have the system installed and OPERATING by Dec 31 of this year to get the 2016 tax credit.

There is always GTA (good until audited), but I like to get things done "cleanly" for the IRS. No sense waving any red flags in front of bulls . . . . .

You have a lot to do - but we can help you. First off, we need your month by month kWhr consumption for past year and the associated costs for kWhrs in the varying seasons and for differing consumption levels. This allows us to figure out how many kW system. Then we figure number of panels. Then we look at roof to see how panels can go up and where. That determines amount of racking and wiring.

Not trying to be scary, but old man winter is puffing up . . . . .


Steve

No pressure!! Right??

We only recently moved into this house, so my data is limited.

July-1581 kWh August-1455 kWh September-1260 kWh

Yesterday was actually step 1 in this process. We rented a lift and took down 3 large trees. One of these completely shaded our southern side of the house, but it needed to go. I will add pictures of the roof in a separate post.

[Roostre]

[Roostre]

[Roostre]

[roflwaffle]

An 8 year payback is a 12+% return on investment, which is pretty good in my experience. That's ~1.5x the real return of the S&P 500 over the past century.

[MN Renovator]

Originally Posted by roflwaffle

An 8 year payback is a 12+% return on investment, which is pretty good in my experience. That's ~1.5x the real return of the S&P 500 over the past century.

It wouldn't be 1.5x the return.
I considered this when I bought my solar system and mine doesn't beat the stock market.
If I consider a conservative average annual return for the total US stock market to be about 7%, that means the value would double every 10 years.
If I figure a lower cost solar system is $10,000(mine was slightly more) after the tax credit, ignore the delay in getting the tax credit money back, and consider the idea that the money put into the solar system is sunk until it comes back out, this is what my math looked like based on my own expected payback.

Solar installed(figuring 8 year payback, but mine is actually over 10) -$10,000
$-8750 Year 1
$-7500
$-6250
$-5000
$-3750
$-2500
$-1250
$0 Year 8
$1250
$2500 Year 10
$8750 Year 15
$10000 Year 16 (Took 16 years to double)
$15000 Year 20
$27500 Year 30

Of course, this isn't accounting for changes in electricity cost or net metering factors specific to your region or electric provider.

Stock market starting with $10,000 with 7% annual return
$10,700 Year 1
$14,025 5
$19,671 10
$27590 15
$38696 20
$76122 30

Compounding returns is powerful. You could take the returns you get from the solar system and invest those in the stock market, but even if you do that, you still need to consider that the price paid for the system is not going to be in the stock market and you've lost the opportunity cost for that initial potential principal. The idea that the original poster is about to otherwise lose the cash and is willing to DIY the install, I'd say that it's still a good move to do.

For what it's worth, the financial component of solar was a factor but I still wanted the solar and I figured it was better than spending the money on a couch, a car, or some other depreciating asset. It is fun for me to look my eGauge power graphs and see the power the system is generating and what the house is using.