Solar questions

[grabeb]

I've been debating installing a DIY solar system on my garage roof. (it would likely be with the aid of a Master Electrician Friend whom is also an electrical engineer) So far we've only lightly discussed and I'm trying to calculate my needs to determine cost to come up with a budget.

It's worth noting my garage and house are on separate meters currently. Plan is to eventually subfeed the house off the garage meter/panel, which is setup for this and conduit is run between the two. I just can't justify $1000 worth of cable to save a $20/mo meter charge. If I go solar, that changes things....

This past November my usage for house was 1320.75kWh and the garage 540.26kWh, so about 1860 between the two. In July I used 2285kWh total. The lightest months, since building garage were about 1300-1400. My garage has South facing roof on an 8/12 Pitch, I believe I can get about 30-35 panels on this roof and meet code for room to walk around. My hope would be to get the invertor, charge controller and all the wiring installed with maybe enough panels to power the garage and get things going, then slowly add to help power the house. Thinking maybe 1/3 then 1/3 then 1/3, that would also keep everything from aging out at once. Garage panel should be setup for this, not sure how the meter works, if that requires a change or not.

I just got off phone with a local solar provider, but they really cater to the full install. He did answer some questions, but left me with a few questions.

He says 30 panels provide about 11Kw of power, so with my roof slope and our area, I'd be getting about 1600kwh in July and about 1200 in Nov. He then said some people use micro invertors to keep cost low at first, but his take was an optimized starting invertor might be best for the long haul in my area. As I said, he isn't really wanting to sell a pieced out system and prefers to do turn key, so he sent me to unbound solar online. He mentioned a 10,000watt invertor if I go string.

I guess I need to know how large of invertor should I be looking at to power everything down the road. I'm guessing I don't need a charge controller unless I add battery backup? This would be grid tied. My understanding is solar is kind of plug-n-play once you get the basics installed, am I mistaken on that? Am I missing something?

 

[ycgoat]

I would use micro inverters, they would help prevent 1 panel or shady area from pulling down an entire string of panels

 

[grabeb]

I would use micro inverters, they would help prevent 1 panel or shady area from pulling down an entire string of panels

I guess I have more to read up on. I'm not sure I knew that existed. I'd been thinking maybe I could start buying parts and pieces as funds allowed then start adding panels. This may still be possible if I go that route, just need to wrap my head around it.

 

[inphx]

I'm at the tail end of a DIY 16.4kw "Permitted" but "Off Grid" install on my toy shop with a plan to use generator model switch over instead of grid tie down the road. I'm in at $27k (19k after tax rebates) , none of this accounts for my time.

From my hands on experience, it seems at my power level there's a few inverter options, but to get 220v a pair of inverters are used in tandem. I chose MMP brand but i see EG4 being popular and there are others. I need/want 220 v for car charging, AC and running a Jacuzzi heater.

Do the cost/benefit calcs in advance for component selection or the cost after making a decision on some items like the inverter are locking you into design options.

In my case the inverters purchased early for supply chain issue reasons - locked me into a max PV (solar panel) input voltage of 145vdc.. so for my 36 panel array - this mean i had to parallel pairs of two (49v + 49v) to distribute panel collection into the four PV inputs on the inverters (2 pv inputs on each) . Be careful on buying parts early, The pro side of this forced decision of having many panels in parallel is durability - if many panels are serial then a weak or failed panel takes out the string. Same for a shady panel (i don't have that issue). The con side is the many pairs of 10awg wire home runs from the panels to combiners. There was 36 wires in my case.

Don't be fooled by end result sort of tidy solutions in photos below - it was a bear to plan the harnesses (so the install of panels can expedit instead of making wires as you go) and with dc needing to be in metal conduit i learned some new skills with wire trays.

Also my inverters are not waterproof so they go inside. If i was to do it again i would buy waterproof inverters with higher PV input (with less wiring) and risk the failure mode of a panel in a string.

Also when buying parts - be aware of your counties rules on not just the walk ways - but what rapid shutdown or cutoff switch codes will apply. Also UL listing may or may not be mandatory. If you are not Grid Tied you may have more leeway. You need to select hardware that best reduces costs instead of adding another.

Hope this helps.

 

[nadogail]

Many people have used contractors or Solar Venders do their "Research and Design" then after getting the thinking done, just doing the job on their own.

That is one of the risks of providing "Free Estimates".

 

[reader2580]

From my hands on experience, it seems at my power level there's a few inverter options, but to get 220v a pair of inverters are used in tandem. I chose MMP brand but i see EG4 being popular and there are others. I need/want 220 v for car charging, AC and running a Jacuzzi heater.

The vast majority of solar inverters supply 240 volts. My two Solaredge inverters along with my four Enphase microinverters all supply 240 volts.

 

[bluedog225]

You will save a bundle if you don’t buy anything until you have the complete system spec’d.

This site will give you good info on production at your location. There is even an hourly production spreadsheet you can download. Use default values for most of it until you learn the details. Works great. https://pvwatts.nrel.gov/

You can save a lot with diy. Not too bad now with all in one units. I’d get a small system in the garage. You will learn a lot. Then you can decide whether to wade into deeper water. Check out the diy solar forum. It has a wealth of info from people in your position. https://diysolarforum.com/whats-new/posts/1896448/

There are a bunch of sketchy installers. And a bunch of 2nd and 3rd tier equipment out there. Tier 1 is Victron (not UL listed though), Sol-Ark, SMA, Enphase, etc. You get what you pay for.

Your jurisdiction may have a lot to say about what you can do.

Ground mount is a lot easier to install and maintain. And mitigates the real fire risk of high voltage DC.

Enphase (microinverters) are top notch but it’s a lot like the Apple ecosystem. Very controlled and co-dependent on other Enphase components.

Hope it goes well.

 

[bluedog225]

Edit-another consideration is grid-tied (harder) versus off-grid. And you will need a battery bank if you want power when the grid goes down.

For an idea of what you are looking at for a complete system, check out currentconnected.com.

The new-ish server rack batteries (LiFePO4) dont’ have the fire potential of lithium ion. Pretty good stuff.

And for a serious system, I’d recommend 48 volt.

 

[WisJim]

In the last few years I have helped a lot of local friends get started with installing their own systems. I can recommend Renvu as a source of info and parts. RENVU If you sign up for an account you can use their estimator on their site and also get weekly emails of specials etc. I've never found their emails to be a problem, so I think it is worth making an account. Most of the folks that I got started on new systems used Renvu to get their components including panels, inverters, mounts, connectors, etc. and then did the installation themselves and hired a local electrician to help with the utility connection. Systems ranged from 3 kw to over 20kw, some roof and some ground mounts. Most used micro-inverters but some used string inverters. My main concern with a roof mounted system is the condition of the existing roof--is it good enough to last another 20 to 30 years or more or will the roof require re-roofing before the panels wear out? (By the way, I have panels first installed in 1982 that still function as designed and produce about 90% of their original power.)