DIY time. I'm ready. Let's do this.

[curtis73]

I've been down Will's rabbit hole of youtubez and I say a huge thank you to Will.

I'm a carpenter, fabricator, and I consider myself a hobbyist electrician, but not licensed. I want to do a DIY solar setup to (at first) reduce what I drag from the grid, and possibly scale up to cover the majority of what I use. (caveat: I would of course use a licensed electrician to do the critical stuff - first, because I'm smart like that, and second, I'll have to have it permitted and inspected which requires a licensed sparky) I live alone and work too much, so my electron use is relatively low. Last year I consumed 6006 kWh without any attempt at being green, so I hope to pare that down to 4500 next year. I learned recently that my grid provider is 77% fossil fuels, so in my brain I'm thinking if I can get 80% of my juice from the sun, I'm at least doing something.

Scouting around my roof, and using some calculations from a crackpot PPA offer from a solar installer, I can probably get up to 5600 watts worth of panels on the roof real estate I have, but I know I'll not get nearly that much since I'm in PA. (very small property, so it has to be roof)

Is this something that is easily scalable? Can I invest in 1kW worth of panels now, then easily add another 500W later and continue until I have what I want? Or will I be constantly upgrading my inverter/charger to match?

For an on-grid system, should I consider storage? Is the convenience of having power in a blackout (which is pretty rare here) worth the maintenance/slight flammability, and the additional isolation needed so I'm not backfeeding and electrocuting linemen?

Thanks for any input.

 

[Q-Dog]

What you do depends a lot on your goals and what your power company will allow. Do you want to save money? Become more independent? Stick it to the man (power company)?

If you don't need backup you dont need batteries. BUT, you may want batteries anyway if your power company does not have favorable buyback of your excess power. With batteries you can store power when you have sun and use up the power you make after the sun goes down, Without batteries, you have no solar power when there is no sun. Yes, batteries cost money and may not make financial sense if you are looking to save money.

Another thought. If aesthetics matter ... Solar panels change so quickly lately that you may want to buy all of your panels at the same time so they match.

 

[MichaelK]

First, looking at your numbers, 6006kWh/365days = 16.5kWh/day. Not a trivial amount of power. Doable, yes, small system, no.

Assuming you want to go with a whole-house system, then I'd say focus on 48V. In Pennsylvania, I'd think you're likely to get maybe 2.5-3.0 sunhours of power in winter, and 5-6 sunhours in summer. A sunhour is that amount of time the sun can power the panels at more or less full capacity.

Do you have an further breakdown as to the time of year you are consuming the most power? Summer air-conditioning, or winter heating? Winter heat will be harder than summer air-conditioning because of reduced capacity.

So, using your average numbers, to make 16.5kWh of power in December with 3 sunhours, you need about 16,500Wh/3 sh = 5500W of solar. So, no, starting out with just 1000W is really not going to cut it. Even with summer values, starting out at ~2700W minimum is likely to be the lowest starting wattage.

Let's break down useage into daytime and nighttime. Let's say you consume 3/4 of your watts in the day, and maybe 1/4 at night? Does that sound reasonable to you? So, you consume ~12kWh of power during the day, and maybe 4kWh at night. You can start there to determine how big your battery needs to be. Let's say you don't want to drain more than 1/3rd of your total battery overnight. That means you need at least 12kWh of storage. At 48V, that works out to be 12000Wh/48V = 250Ah battery.

So, ball-park estimate of what you need to make something workable....

2700W of panels minimum.
60A charge controller
6000-8000W 48V sine-wave inverter
250Ah batteries, minimum size.
A 5-7.5kW generator for days there's just no sun

It is going to be very worthwhile to come up with an itemized list of what you need to power, and when. Knowing when you need the most power is the best information you need for designing your system. Get back to us with more numbers, and we can refine the design for you.

 

[42OhmsPA]

Welcome to solar in PA...
Winter sucks, summer is great.
What angle will your panel be at?